karin fecova msc thesis 2009 for binding

CONUMA RIVER AND LEAGH CREEK INTRUSIVE

COMPLEXES: WINDOWS INTO MID-CRUSTAL LEVELS OF THE JURASSIC BONANZA ISLAND ARC, VANCOUVER ISLAND, BRITISH COLUMBIA

by

Karin Fecova B.Sc., Simon Fraser University, 2007

THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE

In the Earth Science Department

© Karin Fecova 2009

SIMON FRASER UNIVERSITY

Fall 2009

All rights reserved. This work may not be reproduced in whole or in part, by photocopy

or other means, without permission of the author.

ii

APPROVAL

Name: Karin Fecova

Degree: Master of Science

Title of Thesis: Conuma River and Leagh Creek intrusive complexes: windows into mid-crustal levels of the Jurassic Bonanza island arc, Vancouver Island, British Columbia

Examining Committee:

Chair: Andrew Calvert, Professor

______________________________________

Dr. Dan Marshall Senior Supervisor Associate Professor

______________________________________

Dr. Derek Thorkelson Supervisor Professor and Department Chair

______________________________________

Dr. Dan Gibson Supervisor Assistant Professor

______________________________________

Dr. Graham Nixon External Examiner

Date Defended/Approved: ______________________________________

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ABSTRACT

The Conuma River and Leagh Creek intrusive complexes are examples of

mid-crustal portions of the Jurassic Bonanza island arc, located on Vancouver

Island, British Columbia, Canada. The Conuma River locality exhibits layered

intrusions, consisting of alternating hornblenditic and hornblende gabbroic

cumulates, occurring with numerous, contemporaneous small volume mafic to

intermediate intrusions in tonalitic rocks. The Leagh Creek intrusions exhibit

extensive silicic and basaltic magma mingling. Both complexes are interpreted as

products of multiple magma pulses into the solidifying host intrusions. Two new

radiometric hornblende Ar-Ar ages suggest Early to Middle Jurassic ages for two

intrusions from each of the complexes. Geochemical crystallization modeling

shows a genetic link between the Conuma River cumulate hornblenditic and non-

cumulate hornblende gabbroic intrusions via dominantly olivine fractionation.

Conversely, most of the intrusions of both complexes cannot be related by simple

crystallization modeling, suggesting a complex history, involving magma mingling

and assimilation processes.

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ACKNOWLEDGEMENTS

I would like to thank Dr. Dan Marshall, who was a senior supervisor of this

project, for giving me an opportunity to work on my Master thesis project; for

accompanying me patiently in the field; for allowing me to go back to the field in

the following field season to obtain more observations and samples; for leaving

me freedom in all aspects of this project; for teaching me to effectively use the

secondary electron microscope; for being patient with my English and for tireless

re-reading of my manuscript.

I would like to thank Dr. Derek Thorkelson, who was an integral part and

supervisor of this project, for always being ready for geological discussions; for

answering my questions and making sure that I understand a problem; for

challenging me with the questions on tectonics, magmatism, geochemistry and

mineralogy and for giving me comments that helped me in making decisions on

what path to take with the project during its creative stage and until the finish line.

I would like to thank Dr. Dan Gibson, who was also a supervisor of this

project, for giving me feedback and comments on the project and for rigorous

and tireless re-reading of my manuscript.

I would like to thank Dr. Graham Nixon, who was an external supervisor of

this project, for giving me feedback on the project and for spending time with me

in the field while sharing his expertise on geology of Vancouver Island.

v

I would like to thank Reid Staples, who was my office mate and field

assistant, for always keeping his humour alive in the office; for being a patient

assistant and companion in the field; for being a safe and responsible driver

along some “(to me) epic” logging roads in the backcountry.

I would like to also thank the people who were an important part of the

project and without them the project would not exist: Geoscience BC for funding

the project, and prospector Mr. Efrem Specogna, Hard Creek Nickel Corporation

and BC Parks for allowing me to access their properties. I also received precious

help from Dr. Mati Raudsepp from UBC, who assisted me while obtaining

microprobe analyses, and from Tom Ullrich, who obtained for me the Ar-Ar dates.

I would like to thank the lovely ladies Glenda Pauls and Tarja Vaisanen for

their help with all kinds of paperwork (during the grad and undergrad studies) that

is always necessary to do and today‟s world couldn‟t function without it, which

means that I couldn‟t function without them.

I would like to thank the “always-in-a-good-mood” men Rodney Arnold and

Matt Plotnikoff for sharing with me a nice word or joking with me, but most

importantly for helping me with all sorts of technical issues, which made my days

run smoother.

I would like to thank the graduate students, who I made friends with during

the grad studies: Francesca Furlanetto, Liz Westberg, Michael Galicki, Sarah

Brown and Gabe Xue. They always found some time for me to say hi and to chat

or to engage with me in sports. I wish them good luck in their future career!

vi

I would also like to say “thank you” to some people, who may have nothing

to do with my thesis, but this is the only place and perhaps the only opportunity in

my life where I can officially thank them; and because I am not limited by the

space and the content in this portion of thesis, I will take advantage of it.

I would like to thank Kevin Cameron, who accompanied my existence at

SFU as my teacher of numerous geological courses and as a supervising

teacher during my teaching assistant career, for tutoring me on geology with

enthusiasm and dedication and for being humorous and authentic.

I would like to thank Robbie Dunlop, who was my teacher of palaeontology

and introductory field geology, for being easily approachable and honestly

supportive, especially in the early times of my being at SFU, when I needed to

hear from someone that I would be fine.

I would like to thank Mark-André Brideau, who was my first and lovely

boss at SFU and in my geological career, for showing me how to get ready for

the field, how to stay organized and to be effectively productive in the field and

also how to stay calm and easy in bear company; for being comfortable on any

rock slide in the Yukon, Rogers Pass and Coast Mountains backcountry.

I would like to thank my second and also lovely boss at SFU Dr. Brent

Ward, for being easy, humorous; for showing me how to be very productive in

some “(to me) epic” field situations in rough terrains of the Yukon or Queen

Charlotte Islands backcountry; for showing dedication and passion of a mad

scientist during his hunt after Quaternary artefacts in glacial sediments.

vii

I would like to thank all professors that have ever taken me to the field

during my undergrad career, where I found myself always happy and enjoying it.

I thank Dr. Derek Thorkelson for the field geology course and petrology fieldtrip in

the BC interior, who armoured me with solid mapping skills for my future

geological career; Dr. Peter Mustard for the fieldtrip to north of Vancouver, who

got moving my 3D imagination on tectonic processes; Dr. Dan Gibson and Jim

Monger for the Canadian Cordillera traverse fieldtrip; Dr. Dan Marshall for the

fieldtrip to Myra Falls mine and many other professors for their fieldtrips focused

on geomorphology, river studies, environmental geology studies and

geotechnics.

I would like to thank some people from my undergrad studies: Cor Coe,

my patient companion, exam-assignment-school-life “sufferer”, who would never

let me down and with whom I made it through. But my times at SFU would not be

so shiny, if my stars would not be there: Joel Gillham, Brian May, Chris Fozard,

Andrew LaCroix, and Reid Staples. All clouds disappeared when I saw their

beautiful faces.

I would like to thank three more people, although at the end of the list, who

are crucial to my life. These people are my husband Ján Pichler and my parents

Katarína Fečová and Ján Fečo.

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TABLE OF CONTENTS

Approval .............................................................................................................. ii

Abstract .............................................................................................................. iii

Acknowledgements ........................................................................................... iv

Table of Contents ............................................................................................ viii

List of Figures .................................................................................................... xi

List of Tables .................................................................................................... xv

1: INTRODUCTION .............................................................................................. 1

2: PREVIOUS WORK .......................................................................................... 2

2.1 Bonanza island arc: Regional context ................................................ 2

2.2 Bonanza island arc on Vancouver Island ........................................... 4

3: FIELD RELATIONS ......................................................................................... 7

3.1 Conuma River intrusive complex ........................................................ 8

3.1.1 Country rock of the Conuma River intrusive complex ................... 11

3.1.2 Intrusive rock types ....................................................................... 11 3.1.3 Contact relationships .................................................................... 13 3.1.4 Layered intrusions ......................................................................... 15

3.1.5 Magmatic enclaves ....................................................................... 18 3.1.6 Magma mingling and mixing textures ............................................ 18

3.1.7 Pegmatites .................................................................................... 20 3.1.8 Flow structures.............................................................................. 22

3.2 Leagh Creek intrusive complex ........................................................ 23 3.2.1 Country rock of the Leagh Creek Intrusive Complex..................... 23 3.2.2 Intrusive rock types ....................................................................... 25 3.2.3 Contact relationships .................................................................... 25 3.2.4 Magmatic enclaves ....................................................................... 26

3.2.5 Magma mingling and mixing textures ............................................ 28 3.2.6 Flow structures.............................................................................. 30

3.3 Field relations: Summary and conclusions ....................................... 30

4: PETROGRAPHY ............................................................................................ 36

4.1 Olivine hornblendite .......................................................................... 36 4.2 Megacrystic hornblendite ................................................................. 38 4.3 Hornblendite ..................................................................................... 39 4.4 Hornblende gabbro ........................................................................... 41 4.5 Quartz hornblende gabbro ............................................................... 41

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4.6 Plagioclase hornblende gabbro porphyry ......................................... 42

4.7 Hornblende diorite ............................................................................ 44 4.8 Spotted hornblende diorite ............................................................... 44

4.9 Acicular hornblende diorite ............................................................... 45 4.10 Tonalite ............................................................................................ 46 4.11 Trondhjemite .................................................................................... 46 4.12 Metamorphic assemblages .............................................................. 48 4.13 Alteration assemblages .................................................................... 48

4.14 Microstructures ................................................................................. 50

5: MINERALOGY ............................................................................................... 51

6: MINERAL PARAGENESIS ............................................................................ 64

6.1 Hornblendites ................................................................................... 64

6.1.1 Olivine hornblendite ...................................................................... 64 6.1.2 Megacrystic hornblendite .............................................................. 71

6.1.3 Hornblendite ................................................................................. 72 6.2 Hornblende gabbros ........................................................................ 72

6.2.1 Hornblende gabbro ....................................................................... 72 6.2.2 Plagioclase hornblende gabbro porphyry ...................................... 74 6.2.3 Quartz hornblende gabbro ............................................................ 74

6.3 Hornblende diorites .......................................................................... 76 6.3.1 Hornblende diorite ......................................................................... 76

6.3.2 Spotted hornblende diorite ............................................................ 77 6.3.3 Acicular hornblende diorite ........................................................... 79

6.4 Tonalites ........................................................................................... 81

6.4.1 Tonalite. ........................................................................................ 81 6.4.2 Trondhjemite ................................................................................. 81

7: WHOLE ROCK GEOCHEMISTRY ................................................................ 83

8: AR-AR DATING ............................................................................................. 96

9: THERMOBAROMETRY ................................................................................. 98

9.1 Olivine-orthopyroxene thermometer ................................................. 98 9.2 Al2O3 and TiO2 in hornblende thermobarometry ............................. 100

9.3 AlVI in hornblende barometer .......................................................... 102 9.4 Summary and interpretation ........................................................... 104

10: CRYSTALLIZATION MODELING .............................................................. 106

10.1 Crystallization modeling results from the Conuma River and Leagh Creek intrusive complexes (Bonanza arc) ........................... 107

10.2 Crystallization modeling results from basalts, olivine and plagioclase cumulates of Port Renfrew area (Bonanza arc) ........... 110

10.3 Crystallization modeling results from gabbroic rocks of the Port Alberni region (Bonanza arc) .......................................................... 111

10.4 Crystallization modeling results from basaltic and gabbroic rocks from Tazlina Lake (Talkeetna arc) ........................................ 111

10.5 Summary and discussion of crystallization modeling ..................... 112

x

11: TECTONO-MAGMATIC MODEL ............................................................... 119

11.1 General conceptual model for the Bonaza Arc ............................... 119 11.2 Conceptual model as it applies to the CRIC ................................... 120

11.3 Conceptual model as it applies to the LCIC ................................... 122

CONCLUSIONS ............................................................................................... 130

REFERENCES ................................................................................................. 134

APPENDIX 1: FIELD RELATIONS .................................................................. 145

APPENDIX 2: PETROGRAPHY ...................................................................... 186

APPENDIX 3: ELECTRON MICROPROBE DATA .......................................... 193

APPENDIX 4: WHOLE ROCK GEOCHEMISTRY ........................................... 208

APPENDIX 5: GEOCHRONOLOGY ................................................................ 220

APPENDIX 6: CRYSTALLIZATION MODELING ............................................ 224

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LIST OF FIGURES

Figure 1. The Bonanza island arc in regional context.. ......................................... 3

Figure 2. Bonanza arc on Vancouver Island-maps and cross section .................. 4

Figure 3. Geology of Gold River map-area. .......................................................... 7

Figure 4. CRIC outcrop map and interpretative cross section .............................. 9

Figure 5. Field photographs of CRIC .................................................................. 17

Figure 6. Mafic enclaves from the CRIC. ............................................................ 19

Figure 7. Field photographs from the CRIC ........................................................ 21

Figure 8. LCIC outcrop map and interpretative cross section. ............................ 24

Figure 9. Contact relationships in the LCIC.. ..................................................... 27

Figure 10. Field photographs from the LCIC .................................................... 29

Figure 11. Summary of field observations. ......................................................... 31

Figure 12. Schematical petrographical summary ................................................ 37

Figure 13. Photomicrographs of hornblendites. .................................................. 40

Figure 14. Photomicrographs of hornblende gabbros. ........................................ 43

Figure 15. Photomicrographs of hornblende diorites .......................................... 47

Figure 16. Photomicrographs of tonalites. .......................................................... 49

Figure 17. Point analyses in hornblende grains from the CRIC .......................... 53

Figure 18. Representative analyses of calcic hornblendes from the CRIC ......... 53

Figure 19. Compositional variation in hornblendes from hornblendites .............. 54

Figure 20. Compositional variation in hornblendes ............................................. 55

Figure 21. Compositional variation in hornblendes from successive layers ........ 56

Figure 22. Compositional variations in hornblendes from successive layers ...... 56

Figure 23. Graphic representation of plagioclase compositions ......................... 57

Figure 24. Variations in An component in plagioclase ........................................ 58

Figure 25. Plagioclase phenocryst in a quartz hornblende gabbro ..................... 59

Figure 26. Core to rim traverse across the plagioclase phenocryst PPX 1 ......... 59

Figure 28. Core to rim traverse across the plagioclase phenocryst PPX 2 ........ 60

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Figure 27. Quartz hornblende gabbro. ................................................................ 60

Figure 29. Magnesium numbers (Mg#) ............................................................... 62

Figure 30. Compositional changes in ferromagnesian mineral phases .............. 63

Figure 31. Mineral paragenesis in hornblendites. ............................................... 71

Figure 32. Mineral paragenesis in hornblende gabbros ...................................... 73

Figure 33. Mineral paragenesis in hornblende diorites.. ..................................... 80

Figure 34. Mineral paragenesis in tonalites. ....................................................... 81

Figure 35. TAS diagram ..................................................................................... 84

Figure 36. Calc-alkaline vs tholeiitic trend for the CRIC and LCIC ..................... 84

Figure 37. K2O-TiO2-P2O5 discriminant diagram ................................................. 85

Figure 38. Discriminant plots. ............................................................................. 86

Figure 39. Harker diagrams. ............................................................................... 88

Figure 40. Normative mineralogy of CRIC and LCIC. ......................................... 91

Figure 41. Trace elements and REE plots .......................................................... 94

Figure 42. Plateau age of 189.9±2.1 Ma of hornblende from the CRIC .............. 97

Figure 43. Plateau age of 179.7±3 Ma of hornblende from the LCIC ................. 97

Figure 44. A schematic plot of the apparent equilibrium constant (KDOL-OPX) .... 100

Figure 45. A petrogenetic grid with Al2O3 and TiO2 isopleths ............................ 102

Figure 46. Pearce element ratio diagram-Conuma River intrusions. ................ 115

Figure 47. Pearce element ratio plots ............................................................... 116

Figure 48. Generalized tectono-magmatic model. ............................................ 124

Figure 49. Enlargement of the mid-crustal location of CRIC and LCIC ............. 125

Figure 50. A close-up of mid-crustal levels of the Bonanza arc ........................ 126

Figure 51. A close-up of mid-crustal levels of the Bonanza arc. ....................... 128

Figure A1- 1. Outcrop traverses of the CRIC. ................................................... 165

Figure A1- 2. Outcrop traverses of the CRIC. ................................................... 166

Figure A1- 3. Sketch of the CRIC layered intrusion .......................................... 167

Figure A1- 4. A detailed sketch of the CRIC layered intrusion. ......................... 168

Figure A1- 5. A detailed sketch of the CRIC layered intrusion. ......................... 169

Figure A1- 6. Sketch of the CRIC layered intrusion .......................................... 170

Figure A1- 7. Sketch of the CRIC layered intrusion. ......................................... 171

Figure A1- 8. A detailed sketch of part of the CRIC intrusion. .......................... 172





















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xiii

Figure A1- 9. A detailed sketch of the CRIC intrusion. ..................................... 173

Figure A1- 10. Sketch of the CRIC layered intrusion ........................................ 174


Figure A1- 12. A detail sketch from Figure A1-11 ............................................. 176


Figure A1- 14. A detailed sketch from the portion of the CRIC intrusion .......... 178

Figure A1- 15. Outcrop traverses of the LCIC. ................................................. 179

Figure A1- 16. Outcrop traverses of the LCIC .................................................. 180

Figure A1- 17. CRIC layered intrusions and flow structures ............................. 181

Figure A1- 18. Flow structures of the CRIC ...................................................... 182

Figure A1- 19. Flow structures of the CRIC. ..................................................... 183

Figure A1- 20. Magmatic enclaves of the CRIC................................................ 184

Figure A1- 21. Contacts in the CRIC. ............................................................... 185

Figure A2- 1. Photomicrographs of hornblendites ............................................ 187

Figure A2- 2. Photomicrographs of hornblende gabbros .................................. 190

Figure A2- 3. Photomicrographs of hornblende diorites and tonalites .............. 192

Figure A3- 1. Hornblendes from hornblendite and hornblende gabbro ............. 207

Figure A4- 1. An example of an error envelope. ............................................... 215

Figure A4- 2. Whole rock analyses of trace elements from Conuma River ...... 216

Figure A4- 3. Tectonic setting discriminant diagrams ....................................... 217

Figure A4- 4. Triangular tectonic discriminant plots. ......................................... 218

Figure A4- 5. Compositional variations in Conuma River hornblendites. .......... 219

Figure A5- 1. Argon isotope correlation diagrams ............................................ 222

Figure A5- 2. Radiometric dating of the Bonanza island arc ............................. 223

Figure A6- 1. Conserved element plot for Conuma River intrusions ................. 226

Figure A6- 2. Results of crystallization modeling for Conuma River. ................ 229

Figure A6- 3. Results of crystallization modeling for Conuma River ................. 231

Figure A6- 4. Fractional crystallization modeling for Conuma River ................. 232














xiv






Figure A6- 10. Results of crystallization modeling for Conuma River ............... 238

Figure A6- 11. Results of crystallization modeling for Leagh Creek ................. 239

Figure A6- 12. Results of crystallization modeling for Leagh Creek ................. 240

Figure A6- 13. Results of crystallization modeling for Port Renfrew ................. 241

Figure A6- 14. Results of crystallization modeling for Port Renfrew ................. 242

Figure A6- 15. Results of crystallization modeling for Port Renfrew ................ 243

Figure A6- 16. Results of crystallization modeling for Broken Islands .............. 244

Figure A6- 17. Results of crystallization modeling for Talkeetna arc ................ 245










xv

LIST OF TABLES

Table 1. Summary of intrusive varieties of CRIC and LCIC .................................. 8

Table 2. Summarized equilibrium temperature and pressure estimates ........... 104

Table A1- 1. List of samples from Gold River area (NTS 092E/16). ................. 145

Table A1- 2. Selected intrusive lithological types from Gold River area ........... 147


Table A1- 4. Selected intrusive lithological types from Gold River area. .......... 150






Table A1- 10. Outcrops with layered intrusions: Features and structures. ....... 160

Table A2- 1. Detailed petrographic descriptions of intrusive varieties .............. 186



Table A2- 4. Detailed petrographic descriptions of intrusive varieties ............. 191

Table A3- 1. Representative microprobe analyses of olivine and pyroxene ..... 194

Table A3- 2. Microprobe analyses of olivine and pyroxene .............................. 195

Table A3- 3. Representative microprobe analyses of amphiboles .................... 197

Table A3- 4. Microprobe analyses of amphiboles ............................................. 198

Table A3- 5. Representative microprobe analyses of feldspars........................ 202

Table A3- 6. Microprobe analyses of feldspars................................................. 203

Table A3- 7. Representative microprobe analyses of mica and oxides ............ 205

Table A3- 8. Microprobe analyses of mica and oxides ..................................... 206

xvi

Table A4- 1. Whole rock geochemistry analyses .............................................. 210

Table A4- 2. Whole rock geochemistry analyses .............................................. 212

Table A5- 1. 40Ar-39Ar gas release spectra of hornblende ................................ 220

Table A5- 2. 40Ar-39Ar gas release spectra of hornblende ................................ 221

Table A6- 1. Results of crystallization modeling for Conuma River .................. 230

1

1: INTRODUCTION

This thesis project is a part of project 2005-027 “Mineral Potential of the

Westcoast Crystalline Complex, Western Vancouver Island”, funded by

Geoscience BC. Access to new logging roads improved mapping in Gold River

area (NTS 092E/16).

This research focused on characterization of field relationships,

petrography, mineralogy, geochemistry, tectonic setting and geochronology of

layered ultramafic and mafic rocks and associated mafic, intermediate and felsic

intrusive rocks of the Island Plutonic Suite, which is a part of Bonanza island arc

and represents products of Early to Middle Jurassic arc magmatism. The

fieldwork in Conuma River and Leagh Creek localities resulted in the creation of

outcrop maps, conceptual cross sections, outcrop sketches, 27 whole rock

geochemistry samples, and petrographic, EDS and microprobe analyses of 21

thin sections. Ar-Ar ages were obtained from two intrusive samples. The final

tectono-magmatic model for Early-Middle Jurassic arc plutonism on Vancouver

Island summarizes results of all analyses, including simple crystallization

modeling using whole rock geochemistry data.

Lastly, the research of layered outcrops and associated intrusive rocks in

Gold River area revealed a rather limited PGE potential within the layered

intrusions.

2

2: PREVIOUS WORK

2.1 Bonanza island arc: Regional context

The Bonanza arc developed on the pre-existing substrate of the

Wrangellia Terrane consisting of Triassic Nikolai-Karmutsen flood basalts

underlain by Paleozoic Skolai-Sicker island arc crust (Plafker et al. 1989). The

Wrangellia Terrane is part of the Insular Belt, which is the westernmost

morphogeologic belt of the Canadian Cordillera (Monger et al. 1982). The

Wrangellia Terrane was accreted onto the Canadian Cordillera in the mid-

Cretaceous period (Souther 1991; Woodsworth et al. 1991; Yorath et al. 1999).

Early to Middle Jurassic magmatism, located outboard of the North

America craton, and generated along an ancient, northeasterly oriented

subduction zone, produced not only the Bonanza arc, but also a long, continuous

igneous belt that extended north and south of the Bonanza arc (Plafker et al.

1989). Part of this island arc chain is the Middle Jurassic Yakoun arc on the

Queen Charlotte Islands (Sutherland Brown 1968; Woodsworth et al. 1991),

which is also built upon the Wrangellia substrate. The Early to Middle Jurassic

Talkeetna island arc of the Peninsular Terrane, located in the south-central

Alaska (Fig. 1) (Plafker et al. 1989; Burns 1983, 1985, 1996; DeBari et al. 1999;

DeBari and Sleep 1991; DeBari and Coleman 1989; Hacker et al. 2008; Greene

et al. 2006) is believed to represent the northernmost continuation of this island

arc chain. The southernmost end of this igneous belt likely extended along the

3

western margin of the North America continent, as far south as Mexico (Plafker

et al. 1989). The Wrangellia and Peninsular terranes share lithological,

paleontological, temporal and paleomagnetic similarities, both terranes

experienced post-Triassic latitudinal displacement , along regional strike-slip

faults, of approximately 30o north with respect to the North American craton, and

by 52 Ma they were both in their present positions (Plafker et al. 1989). In

Alaska, both terranes are bounded to the south by the Border Ranges fault

system, which may represent an ancient subduction zone along these terranes

(Plafker et al. 1989). Today, the Border Ranges fault system represents a

tectonic contact between these two terranes and the Chugach Terrane, an

oceanic accretionary complex, juxtaposed against the Wrangellia and Peninsular

terannes between Early Jurassic and Paleogene (Plafker et al. 1989).

Figure 1. The Bonanza island arc in regional context. The Bonanza arc on Vancouver Island and Yakoun arc on Queen Charlotte Islands are components of Wrangellia Terrane (WR). The Talkeetna arc in south-central Alaska is a component of Peninsular Terrane (PE). All three arcs are products of Jurassic magmatic activity, shown in red and green and likely formed a long continuous island arc chain that had been fragmented and displaced along regional faults. Abbreviations: TL=Tazlina Lake; CRIC=Conuma River intrusive complex; LCIC=Leagh Creek intrusive complex; PR=Port Renfrew; BI=Broken Islands. 2008 Google Earth map.

4

2.2 Bonanza island arc on Vancouver Island

A simplified section (Fig. 2) through stratigraphy of Vancouver Island,

which shows position of Conuma and Leagh intrusive complexes within the

Bonanza arc, summarizes the results of geological field work and research on

Figure 2. Bonanza arc on Vancouver Island-maps and cross section. A: Index map for Vancouver Island. B: Vancouver Island with the distribution of the Jurassic Bonanza arc units (pink, purple and bluish green) from Map Place: BCGS 2005 layers (Massey et al. 2005). The yellow stars indicate the location of the Conuma River and Leagh Creek intrusive complexes and other studied localities of the Island Plutonic Suite. C: A simplified cross section summarizing the geology of Vancouver Island showing the Bonanza island arc units (pink, purple and bluish green) and the position of the Conuma River and Leagh Creek intrusive complexes within the Bonanza arc. The thicknesses of individual units are approximated subsurface thicknesses as observed in Alberni region (Yorath et al. 1999). The age assignments for Bonanza and Vancouver groups as suggested by Nixon and Orr (2007). The Vancouver Island crust was built dominantly by four major magmatic events indicated with black bars and labels left of the cross section. Abbrevations: SVI=Southern Vancouver Island, MI=Meares Island, PR=Port Renfrew, PA=Port Alberni, BI=Broken Islands, BR=Bedwell River, NI=Nootka Island.

5

Vancouver Island. The oldest rocks are the Paleozoic Sicker and Buttle Lake

groups (volcanic and marine sedimentary rocks), representing an incipient island

arc setting. The Triassic Karmutsen oceanic plateau flood-basalts overlie the

Sicker and Buttle Lake groups. These Paleozoic and Triassic rocks served as a

substrate for Early to Middle Jurassic magmatism, which formed the mature,

emergent Bonanza island arc. Clastic sedimentary rocks of the Nanaimo Group

were deposited in the Late Cretaceous. Magmatic activity resumed in the Tertiary

in a forarc setting resulting in the Flores Island volcanic rocks and the Mount

Washington and Clayquot Plutonic suites. The whole sequence is capped by the

Tertiary marine clastic rocks of the Carmanah Group. Characteristic structures of

Vancouver Island are northwesterly trending faults and anticlinoria (Yorath et al.

1999; Muller et al. 1981, Muller 1989).

The Bonanza arc magmatism has been studied by a number of workers.

Units within the Bonanza island arc are described from southern Vancouver

Island (Yorath et al. 1999), Meares Island (Isachsen 1986), Port Renfrew area

(Larocque and Canil 2007; Larocque 2008), Port Alberni and Broken Islands area

(DeBari et al 1999; Muller 1989), Bedwell River area (Sargent 1941), and Nootka

Sound area (Muller et al. 1981). The Jurassic age of the Bonanza arc has been

determined by zircon, K-Ar and Ar-Ar dating and summarized by DeBari et al.

(1999), Isachsen (1986), Muller et al. (1974). Isotopic work on the Bonanza arc

was performed by Andrew et al. (1991) and Andrew and Godwin (1989 a, b).

The Bonanza arc crust has been divided into three parts: the deepest arc

portion is the Westcoast Crystalline Complex. Middle and upper crustal levels are

6

represented by the Island Plutonic Suite and the Bonanza Group is found at the

highest crustal levels (DeBari et al. 1999). The Westcoast Crystalline Complex

can grade into the Island Plutonic Suite, which makes it difficult to distinguish

between these two units (DeBari et al. 1999). Workers suggest that plutonic

rocks lacking gneissic foliation and intruding the Triassic Karmutsen and Jurassic

Bonanza Group qualify as the Island Plutonic Suite, in contrast with plutonic

rocks of Westcoast Crystalline Complex that show gneissic foliation and intrude

Paleozoic Sicker arc rocks (DeBari et al. 1999).

The Westcoast Crystalline Complex is composed of ultramafic and mafic

rocks comprising two pyroxene hornblende gabbro, pyroxenite, sheared

serpentinite of cumulate nature, strongly foliated hornblendite, hornblende

gabbro, hornblende diorite, tonalite and rare granodiorite (DeBari et al. 1999).

Occurrences of Bonanza ultramafic bodies on Vancouver Island are rare and

reported primarily from Meares Island (Isachsen 1986) and the Port Renfrew

area (Larocque and Canil 2007; Larocque 2008). These have been assigned to

the Westcoast Crystalline Complex. Plutonic rocks of the Island Plutonic Suite

outcrop as northwest trending batholiths and stocks of dominantly hornblende

diorite, quartz diorite and granodiorite compositions. They can also have

gabbroic, tonalitic and granitic compositions (DeBari et al. 1999; Yorath et al.

1999). The Bonanza Group consists dominantly of calc-alkaline volcanic rocks of

basalt and basaltic andesite to rhyolite compositions (DeBari et al. 1999; Yorath

et al. 1999).

7

3: FIELD RELATIONS

The Island Plutonic Suite is a plutonic product of Early to Middle Jurassic

magmatism, and represents a portion of a mature Bonanza island arc forming on

the Wrangellia terrane. Two studied areas, the Conuma River and Leagh Creek

localities (Fig. 3), are examples of intrusive complexes in the Nootka Sound

region, located approximately 30 km W-NW from the town of Gold River. The

terms Conuma River intrusive complex (CRIC) and Leagh Creek intrusive

complex (LCIC) are informal and emerged from this work. They will be used in

this thesis as representative examples of intrusive complexes (i. e. intrusions)

comprising the Island Plutonic Suite. If present in the field, the margins of

complexes would be defined by country rock xenoliths. Recently, only the

Figure 3. Geology of Gold River map-area with the locations of the CRIC and LCIC. Modified from Map Place-BCGS Geology layer 2005-Bedrock geology-Contacts and faults (<1.5M) (Massey et al. 2005). The age assignments for Bonanza and Vancouver groups as suggested by Nixon and Orr (2007).

8

western margins of the complexes can be defined by Karmutsen country rock

and the southern, eastern and northern boundaries remain undefined.

Numerous intrusive varieties are described at the handspeciman scale in

Appendix 1: Table A1-2-9. Rigorous classification and nomenclature (Le Maitre

2002) was applied to the intrusive varieties, from which thin sections and whole

rock geochemistry were obtained. These intrusive varieties (Table 1), described

petrographically in Chapter 4, are also included in Appendix 2: Table A2-1-4.

Table 1. Summary of intrusive types and varieties in the CRIC and LCIC. Major intrusive types include numerous varieties. Selected varieties (listed here) were studied petrographically.

3.1 Conuma River intrusive complex

The CRIC was mapped at a 1:2000 scale over approximately 4 km2. A

conceptual cross section (Fig. 4) represents a possible scenario for the complex

magmatic history of the area. This complex was also mapped in detail at 1:1

scale with a special attention paid to cross-cutting relationships, contacts, flow

structures and textures of layered and other intrusive units (Appendix 1: Table

A1-10; Figs. A1-1-13).

9

Figure 4. CRIC outcrop map and interpretative cross section. A: CRIC outcrop map shows station ID’s related to photographs and/or sketches in the main text and Appendix 1. Intrusions of Island Plutonic Suite (shown in pink in figure 2 and 3) are displayed in white and greys. B: Interpretative cross section with layered intrusions located approximately in the middle of the section. Contacts between intrusions (solid black lines) are contemporaneous, abrupt or gradational (see the main text for the definitions of contacts). Attitudes of contacts are interpretative. Attitude of local magmatic flow and size of Karmutsen blocks in the cross section are also interpretative. The cross section does not include the dykes shown in A. C: Enlargement of the inset with the locations of layered intrusions (next page with a map legend).

10

Figure 4. (Continued)

11

3.1.1 Country rock of the Conuma River intrusive complex

The Triassic Karmutsen Formation is the country rock along the western

margin of the CRIC (Fig. 5A). In the outcrop the Karmutsen Formation is a black

weathering, dark green fresh, plagioclase phyric basalt with 5-10% 1-2 mm light

green plagioclase glomerocrysts. The contact between the CRIC and the

Karmutsen is sharp. At the contact, the country rock is brecciated into angular

clasts generally at the centimetre-scale, but commonly ranging up to metre-scale.

Preserved pillow outlines and ductily deformed pillow selvages are visible at the

outcrop scale. The timing of deformation of pillow selvages and feldspar veinlets

in the Karmusten Formation is unknown but likely occurred during the Jurassic

and is restricted to the contact zone with the CRIC. No sense of movement has

been obtained from these deformational structures, nor is there evidence of a

high temperature contact aureole within the Karmutsen Formation. Greenschist

facies metamorphic grade is characteristic for both the Karmutsen Formation and

the CRIC.

3.1.2 Intrusive rock types

A simplified approach in naming plutonic rock types was applied in the

field. Varieties of the plutonic rocks observed in the field were mapped as a few

major rock types and are listed in order from ultramafic to felsic composition:

hornblendite, hornblende gabbro, hornblende diorite, hybridized diorite1, tonalite

and trondhjemite.

1 The term “hybridized diorite” is applied to mesocratic rocks of mafic to intermediate compositions with

textures suggesting mingling and/or mixing of basaltic and felsic magmas (Wiebe 1980).

12

The intrusions have varying volumes (over cm3 to hundreds of m3),

varying grain sizes (very fine- to very coarse-grained) and varying modal

abundances and textures. Grain size, modal abundance and texture can change

over centimetre and/or metre intervals. It is possible that if each single intrusive

variety of the complex is recorded, it would fill the theoretical compositional tie-

line between two compositional intrusive end members in the area: hornblendite

and tonalite.

The dominant mineral phases in all intrusive varieties are dark (blackish-

green) hornblende and light (whitish-grey) plagioclase. The colour index2 and

hornblende to plagioclase ratio were the key factors in naming intrusive rocks in

the field.

Hornblendites include all melanocratic varieties containing 90-100%

hornblende and are the least abundant intrusive rock type. Very coarse-grained

olivine hornblendites are restricted to layered outcrops, more commonly coarse-

to medium-grained hornblendites occur as sheets in the layered outcrops and

also as stocks and magmatic enclaves within the tonalite.

Mafic rocks with colour index from 90 to 40 were mapped as hornblende

gabbros and those with colour index from 40 to 10 as hornblende diorites.

Hornblende gabbro and hornblende diorite are the most abundant intrusive rock

types. Hornblende gabbro is found as stocks, sheets in layered outcrops and as

magmatic enclaves in tonalite. Hornblende diorite commonly occurs as magmatic

enclaves in tonalite and hybridized diorite.

2 Colour index is volume percent of dark minerals contained in a rock (see Table 1).

13

Leucocratic rocks of felsic compositions were mapped as tonalite and

hololeucocratic rocks were mapped as trondhjemite. Tonalitic, trondhjemitic and

hybridized dioritic intrusive varieties occur as narrow dykes, veins and as an

intrusive network. They can be traced at metre-scale between hornblenditic,

hornblende gabbroic and hornblende dioritic units.

3.1.3 Contact relationships

Contacts between all intrusive varieties are typically abrupt or gradational.

Both show strong evidence of contemporaneity of intrusions.

Abrupt contacts exist between two intrusions that differ by modal

abundance and/or grain size and/or texture and do not display chilled margins.

A good example of an abrupt contact can be found between hornblenditic

varieties, hornblenditic and gabbroic sheets, between coarse-grained magmatic

enclaves and tonalite and between some tonalites, trondhjemites and hybridized

diorites (Fig. 5B, C).

Gradational contacts exhibit similar changes over cm and/or metre scales.

A typical gradational contact is usually interpreted as an indicator of magma

mingling (see section 3.1.6 for the definition and description of mingling), and can

be found between hornblende gabbro stocks and tonalite or hybridized diorite,

where hornblende gabbro grades into tonalite in the form of a hornblende

gabbroic/ dioritic zone characterized by distinctive acicular and/or spotted

hornblende textures (Appendix 1: Figs. A1-21D, E). Medium-grained

14

hornblendite was also observed grading into a spotted hornblendite variety, with

4 mm hornblende spots in a 1-2 mm hornblendite groundmass (Fig. 5C).

Chilling of one intrusion against another (i.e. chilled margin) is generally

expressed as a decrease in grain size in one intrusion toward the contact with

the other (Appendix 1: Figs. A1-21A). The most common type of chill texture is

found in chilled mafic enclaves, where mafic melts chilled against the cooler

tonalitic crystal mush, resulting in aphanitic texture or acicular hornblende

crystals, whose grain size may or may not decrease toward the contact with

tonalite. The presence of acicular hornblende and numerous apatite needles

observed in thin section are sufficient evidence of “chilling” and indicate a

temperature gradient during emplacement into a cooler host intrusion (Appendix

1: Figs. A1-21B). Another clear example of chilling – only found in one location -

is displayed by coarse- to medium-grained hornblendite developing a medium-

grained margin at the contact with medium-grained tonalite (Appendix 1: Fig. A1-

21C). Some trondhjemite dykes and small stocks have chilled against the tonalite

or mafic and ultramafic intrusions.

In some cases the contact between two intrusions can be defined by

aligned, medium-grained hornblende crystals forming continuous or

discontinuous strings. It is possible that the hornblende strings developed by a

combination of a temperature gradient and shear along the interface between

two intrusions. The temperature gradient would affect formation of pyroxene

(replaced by hornblende) crystals from hotter magma by enhancing their

nucleation rate along the undercooled interface in contact with a “cooler” magma.

15

The shear force existing between two flowing intrusions would be responsible for

the crystal alignment. Hornblende strings exist between tonalitic and hornblende

gabbroic/ hornblende dioritic intrusions (Appendix 1: Fig. A1-14). In one case

such a string exists along the contact between two hornblenditic sheets. The

grain size in both sheets increases subtly from medium- to coarse-grained away

from the string (contact). This could be a product of temperature gradient and

shear combined with a flow differentiation characterized by concentration of

already formed crystals in the central zone of flowing magma.

3.1.4 Layered intrusions

The CRIC has a dominant structural feature, which is a N-S oriented band

of layered outcrops approximately 70 by 450-900 m, and consisting of alternating

sheets of hornblenditic and gabbroic intrusions (Fig. 5D; Appendix 1: Figs. A1-1-

7; A1-10-14; A1-17, 18; Table A1-10). The seven layered outcrops have heights

ranging from 2-10 m with strike-lengths of 5-50 m and 1.5 m exposures in the

third dimension. The layered intrusions have an average strike of 020o ± 20 o and

a dip of 50o ± 10 o. The variation in attitude of layers may be due to brecciation of

the layered intrusion into large blocks after emplacement, and later movement

along local faults.

Sheeted intrusions display the following alternating patterns:

Very coarse-grained olivine hornblendite alternating with medium-

grained hornblende gabbro

16

Very coarse-grained olivine hornblendite alternating with coarse- to

medium-grained quartz hornblende gabbro

Medium-grained hornblendite with hornblende megacrysts

alternating with medium-grained gabbro

Medium-grained hornblendite with hornblende megacrysts

alternating with very coarse-grained olivine hornblendite

Narrow recessive sheets of very coarse-grained olivine

hornblendite alternating with thick units of the same rock type

Layered intrusions occur as discontinuous isolated outcrops and no

tectonic or intrusive contact between these outcrops and the surrounding rocks

were observed, and no correlation of individual sheets from outcrop to outcrop

was possible. Flow structures in layered intrusions are represented by

sheeted nature of intrusions

convoluted, irregularly disturbed, and smeared margins of sheets

alignment of crystals in sheets, subparallel to layering

presence of lenticular and flaser structures and pinching layers

presence of positively weathered lensoid structures defined by

recessive erosion with an anastomosing pattern

17

Figure 5. Field photographs of CRIC. A: Brecciated Karmutsen Formation (KF) country rock intruded by tonalite (T). B: Abrupt contact between trondhjemite (TR) and tonalite (T) (black arrow) and between tonalite and hornblende diorite (HD) (white arrow). Abrupt contact between trondhjemite and hornblende diorite (white dashed arrow). C: Abrupt (white arrow) and gradational (white dashed arrow) contact between hornblendite (H) and spotted hornblende gabbro (SH). D: Layered outcrop exhibiting alternating olivine hornblendite (OH) and quartz hornblende gabbro (HG) sheets. Hornblende gabbro sheets are wavy, slightly deformed and smeared by flow in olivine hornblendite. The white dotted arrow indicates trace of flow foliation. Sledge hammer for scale in orange rectangle. Photo ID (P-prefixed) numbers in the figures refer to locations in figure 4 and appendices.

18

3.1.5 Magmatic enclaves

Volumetrically dominant in both complexes, mafic to ultramafic and

intermediate enclaves occur in tonalite and hybridized diorite (Appendix 1: Figs.

A1-19B-D, F; A1-20). They occur as very fine-grained melanocratic inclusions;

fine- to medium acicular hornblende dioritic inclusions and medium- to coarse-

grained hornblende gabbroic and hornblenditic inclusions. All magmatic enclaves

range in size from cm to metre scale and have round to angular shapes (Fig. 6A).

They can be undeformed to elongate and oblate, reflecting various amounts of

strain. Maximum deformation is characterized by either wispy and/or ghost-like

appearance. Their margins range from smooth and straight to lobate and cuspate

to irregular and smeared-out by flow within the intrusive host (Figs. 6A, B). They

often show subparallel alignment caused by flow in tonalite or hybridized diorite

(Fig. 6C). Some display a 1 cm wide positive-weathering rim at their margins with

tonalite. They occur in abrupt and chilled contact with tonalite and may contain

xenocrysts or clusters of crystals (xenoliths) entrained from tonalite (Fig. 6D, E).

3.1.6 Magma mingling and mixing textures

Mingling and mixing textures result from interactions of magmas prior to,

during and after emplacement. Magma mixing and mingling are believed to be a

common process in intrusive environments (Wiebe 1980). The likelihood of two

mingling or mixing magmas to has been studied by many workers (McBirney

1980; Frost and Mahood 1987; Sparks and Marshall 1986; Grammatikopoulos et

al. 2007).

19

Figure 6. Swarms of mafic enclaves (MF) are common in the CRIC. They have varying shapes, sizes and lithology ranging from hornblendites to hornblende diorites. They intruded tonalite (T), partially melting and remobilizing it. A: Flowing tonalite disrupted the margins of the mafic enclaves (white dashed arrow), and produced faint and wispy dark schlierens. Some mafic enclaves show white distinctive plagioclase crystals (white solid arrows) that may be either phenocrysts or xenocrysts (magma mixing) entrained from magmas prior to or during emplacement. B: Margins of mafic enclaves are either smooth and planar, or more commonly lobate or cuspate (outlined by white dotted arrows that also indicate trace of flow foliation). TR = trondhjemite dyke cutting across the mafic enclave. C: Subparallel alignment of mafic enclaves (MF) in tonalite (T). Dotted arrows indicate trace of flow foliation. D: Acicular hornblende diorite (AH) enclave mingled with tonalite that was flowing (T). White solid arrows point to entrained tonalitic crystals and xenoliths now contained within the enclave. White dotted arrows indicate trace of flow foliation. E: Some mafic enclaves display a decrease in grain size toward the contact (in direction of the white arrow) with what was a cooler flowing tonalite (T). Often the acicular hornblende (AH) texture occurs in the mafic enclave and is interpreted as a result of a temperature gradient (see section 6.3.3 for the mineral paragenesis of acicular hornblende diorite).

20

Unlike mingling, mixing involves a more thorough homogenization of low

viscosity magmas and involves extensive chemical and physical exchange

(Wiebe 1980). This process is interpreted to have taken place prior to

emplacement based on field observations.

Mingling commonly occurs at the contact zone between magmas of

different viscosities interpenetrating each other, and is accompanied by limited

chemical exchange (Wiebe 1980). Based on field evidence, mingling likely

occurred during and after emplacement. Resulting textures typically display blebs

of one magma within another (Figs. 7A, B; Appendix 1: Figs. A1-21A, B). Field

observations indicate that magma mingling can also be characterized by spotted

hornblende textures that are present in hornblende gabbros and hornblende

diorites. The spotted hornblende texture is typically found in a gradational contact

zone between tonalite and hornblenditic and hornblende gabbroic enclaves (see

section 3.1.5 for the definition and description of gradational contacts).

Other products of mingling include disequilibrium textures in the form of a

crystal rim from a magma that surrounded crystals from another magma (Figs.

7C, D). These include examples of feldspar and hornblende crystals mantling

quartz and feldspar xenocrysts from the host tonalite embedded in hornblende

dioritic enclaves.

3.1.7 Pegmatites

Pegmatites are commonly found within the intrusive bodies (Fig. 7E). They

form pockets and/or pods at the centimetre-scale and usually consist of feldspar

21

Figure 7. A: Magma mingling between olivine hornblendite (OH) and hornblende gabbro (HG) in the CRIC. Hornblende gabbro contains plagioclase crystals (white arrows) that are interpreted as xenocrysts entrained by gabbroic magma prior to or during its emplacement. The white double-arrow cuts across the gradiational contact. B: Mingling of CRIC acicular hornblende diorite (AH) and tonalite magma indicated by arrow. C: Mixing between acicular hornblende diorite and tonalite magmas in the CRIC. Arrows point to quartz crystals mantled by reaction rim (feldspars). D: Mixing and mingling of CRIC tonalitic and hornblenditic magmas producing hybridized diorite containing hornblende megacrysts from hornblendite mantled by a disequilibrium feldspar-rich reaction rim (arrows) in tonalite and hybridized diorite. E: CRIC pegmatitic pocket of white plagioclase and green bladed hornblende in hornblende diorite.

22

and hornblende. Feldspar forms tabular, white, up to 3 mm crystals intergrown

with prismatic, green, up to 1 cm long hornblende crystals. These pockets are

found in medium-grained hornblendites, hornblende gabbros and hornblende

diorites.

3.1.8 Flow structures

Flow structures (Appendix 1: Figs. A1-18, 19) are prevalent in the area.

They occur not only within the previously described layered intrusions, but

throughout the complex, as aligned and stretched magmatic enclaves in tonalite

and hybridized diorite, and as wisps, streaks and schlierens in all major intrusive

rock types. Flow is also identified by a subparallel alignment of crystals along the

contact between tonalite, hybridized diorite and magmatic enclaves.

Along the eastern boundary of the layered structure, the elongated mafic

enclaves exhibit magmatic flow in tonalite with a strike subparallel to the strike of

the sheets within the layered intrusions. It is worth noting that the magmatic flow

dips in the opposite direction to the dip of the layered intrusions. The significance

of the subparallel strikes and the opposite dip directions cannot be resolved from

the field observations. Magmatic flow defined by stretched mafic enclaves in

tonalite elsewhere in the complex is random and not consistent with the attitude

of the sheeted intrusions.

Nodules were observed in one location and can be described as rounded

and epidotized 20 cm pods. Nodules (Appendix 1: Fig. A1-17F) are likely to be

associated with flow processes (Miller 1934). The nodules are randomly

23

distributed and comprise 15% of the 7 m x 5 m outcrop area. They occur within

the medium- to coarse-grained spotted hornblende gabbro intrusion.

3.2 Leagh Creek intrusive complex

The mapped portion of the LCIC stretches over 10 km2. A conceptual

cross section (Fig. 8) represents a possible scenario for the complex magmatic

history of the LCIC. This complex was mapped at a 1:2000 scale and at larger

scales with special attention paid to textures and cross-cutting relationships

between the intrusive varieties (Appendix 1: Figs. A1-14, 15). Rare pegmatitic

pods were observed in the LCIC, but no layered or ultramafic intrusions were

seen. Mapping revealed similarities in intrusive varieties, modal and textural

variations, contact relationships, magma mingling features and general cross-

cutting relationships between individual intrusions of the LCIC and CRIC.

3.2.1 Country rock of the Leagh Creek Intrusive Complex

The LCIC intrudes Karmutsen country rock on its western margin. No

significant metamorphic aureole or major deformational features are present in

the intruded country rock. The Karmutsen Formation is a medium green

weathering, medium grey fresh aphanatic rock with poor or absent plagioclase

phenocrysts. It is brecciated along the contact with distinctive angular clasts at

the centimetre to metre-scale. The rocks show chlorite alteration associated with

the intrusion of the Island Plutonic Suite. In some areas pillow selvages display a

metasomatized assemblage of epidote, garnet, potassium feldspar, and calcite.

These selvages are cross-cut by tonalite.

24

Figure 8. A: LCIC outcrop map. Intrusions of the Island Plutonic Suite (shown in pink in figure 2 and 3) are displayed in greys. B: Interpretative cross section of LCIC. Contacts between intrusions (solid black lines) are contemporaneous, abrupt or gradational (see the main text for the definitions of contacts) and their attitude is interpretative. The size of Karmutsen blocks is also interpretative. Cross section does not include the dykes shown in A.

25

In one location, the orientation of the contact between the Karmutsen

Formation and tonalite is 220°/25°NW (Fig. 9A). Otherwise, the attitudes of the

contact are random. Blocks of the Karmutsen Formation are also found in the

spotted hornblende gabbro intrusion.

3.2.2 Intrusive rock types

The LCIC consists of mafic to intermediate intrusions of varying volumes,

grain sizes, modal abundances and textures with dominant hornblende and

plagioclase phases. These intrusions are cross-cut by, later stage Jurassic to

Eocene dykes such as fine- to medium-grained tonalites and trondhjemites and a

number of ~ 10 cm narrow dykes of green, aphanatic plagioclase-(hornblende)

dacites/andesites.

The most voluminous intrusive varieties are medium-grained hornblende

gabbros and hornblende diorites occurring as stocks and magmatic enclaves

intruding each other, host tonalitic and hybridized dioritic intrusions (Fig. 9B), and

the Karmutsen volcanic rocks. The western part of the mapped area is

characterized by a vein network of the host intrusion of hybridized diorite,

occurring at ten metre intervals between mafic and intermediate intrusions.

Similarly, tonalite can be found as a host vein network in the northern and

eastern part of the mapped area.

3.2.3 Contact relationships

Contacts between the hornblende gabbroic and hornblende dioritic

intrusive varieties and the hybridized diorite and tonalite are gradational or

26

abrupt (Fig. 9C), and are consistent with a contemporaneous intrusive

relationship.

Commonly chilled contacts display a decrease in grain size from medium-

to fine-grained toward the margins of magmatic enclaves in tonalite and/or the

formation of aphanatic margins in mafic enclaves in contact with either hybridized

diorite or tonalite (Fig. 9D). Some of the hybridized dioritic enclaves show chilled

margins against other hybridized diorites.

A combination of a chilled and gradational contact is often characterized

by the acicular hornblende texture. This observation strongly supports the idea

that the acicular hornblende texture is related to “chilling” and can occur over the

centimetre-scale interval defining a contact zone between hornblende gabbro

and hornblende diorite enclaves and the host hybridized diorite and tonalite.

3.2.4 Magmatic enclaves

Magmatic enclaves range in composition from mafic to intermediate and

occur in tonalite and hybridized diorite. Very fine- to fine-grained melanocratic

enclaves are the most abundant. The magmatic enclaves commonly include fine-

to medium-grained acicular hornblende diorite occurring in a host acicular

hornblende dioritic intrusion. Also present are smaller angular blocks of

magmatic enclaves of coarse-grained hornblendite in hybridized diorite (Fig.

10A); these represent the only observed ultramafic intrusions in the LCIC.

The magmatic enclaves range in size, shape, grain size, degree of

deformation and type of margins (see CRIC magmatic enclaves above). The

27

Figure 9. Contact relationships in the LCIC. A: Karmutsen Formation (KF) country rock intruded by tonalitic intrusion. B: Mafic enclaves of hornblende gabbro (HG) are commonly found either in the tonalitic host or hybridized diorite (HYB) host. Flow banded hybridized diorite contains preferentially aligned plagioclase crystals (arrow) indicating mixing of the gabbroic and tonalitic magmas prior to or during the emplacement. Dotted arrows indicate trace of local flow foliation. C: Gradational – marginal mingling contact between hornblende gabbro (HG) and tonalite (T) (arrows point to a mingling zone). D: Mafic enclave (MF) of acicular hornblende diorite displays a decrease in grain size toward the margin (in direction of the arrow) at the contact with cooler hybridized diorite (HYB) host.

28

magmatic enclaves can be stretched, ghost-like (Fig. 10B) and rounded (Fig.

10C). Another example is small magmatic enclaves in the form of mesh-like and

fluid-like fine-grained hornblende gabbro found in medium- to coarse-grained

hornblende gabbro and in tonalite (Fig. 10D).

One location exhibits four types of magmatic enclaves (i.e. magma

mingling textures) across 4 m2 area. Two angular xenoliths of coarse-grained

hornblendite (Fig. 10E) are entrained within medium-grained acicular hornblende

gabbro, which is a mafic enclave in medium-grained acicular hornblende diorite,

and forms a strongly lobate and cuspate abrupt contact with hornblende diorite

(Fig. 10F). The hornblende diorite then grades irregularly into a hybrid diorite, as

well as into another variety of medium-grained acicular hornblende gabbro.

3.2.5 Magma mingling and mixing textures

“Thorough” basaltic and silicic magma mingling (see section 6.3.2 for the

description of “thorough” mingling) is interpreted to result in the formation of the

spotted hornblende texture. Spotted hornblende gabbro/ hornblende diorite3 with

hornblende ranging up to 7 mm in diameter occurs as a voluminous intrusion

locally mingled with smaller volume acicular hornblende dioritic intrusions.

Magma mingling is also typically exhibited as crystals or clusters of

crystals from tonalite being incorporated into and thoroughly mingled with

hornblende gabbros and hornblende diorites. The host hybridized dioritic

3 Assigning a name of hornblende gabbro or hornblende diorite to the voluminous intrusions with

spotted hornblende texture in the LCIC was based only on the colour index (CI). Spotted hornblende gabbro has CI > 45 and spotted hornblende diorite has CI< 45. CI varies locally.

29

Figure 10. A: LCIC angular hornblendite (H) xenoliths entrained during fragmentation of nearly solidified hornblendite at greater depths by ascending gabbroic (HG) magma. B: LCIC stretched and elongated mafic enclaves (MF) in tonalite (T). Arrows indicate trace of local flow foliation. C: LCIC small, rounded, aphanatic mafic enclaves (MF, arrows) dispersed and quickly cooled in tonalitic (T) host magma. D: LCIC irregular, mesh-like or fluid-like, fine-grained mafic enclaves (MF) intruding the host hybridized diorite (HYB) as small basaltic injections which mingled with hybridized host during emplacement. E: LCIC showing two types of magmatic enclaves: Hornblendites (H) entrained by ascending gabbroic (HG) magma intruding into acicular hornblende diorite (AH) that was most likely produced by mixing of tonalitic and basaltic magmas prior to the emplacement. The rectangle indicates the location of F. F: A close up of the margin of the hornblende gabbroic enclave, which has curved lobate and cuspate margins with abrupt contacts and no chill textures against the acicular hornblende dioritic intrusion of the LCIC.

30

intrusion contains a maximum of 20% feldspar xenocrysts - with or without

reaction rim - entrained from tonalitic magma. This is interpreted as indicative of

a thorough mingling texture. Mixing was not confirmed by additional analyses,

but was deduced from the distinctive appearance of the feldspar crystals –

without reaction rim - resembling those observed in the tonalite (Fig. 11L).

3.2.6 Flow structures

Flow structures in tonalite are recognized by the alignment of biotite flakes

in tonalite, or by the alignment of feldspar crystals in magmatic enclaves. Flow

structures are associated with marginal mingling textures, typically by

incorporating and aligning plagioclase crystals from tonalite into mafic enclaves.

3.3 Field relations: Summary and conclusions

Conuma River and Leagh Creek igneous complexes dominantly consist of

mafic and intermediate intrusions with hornblende and plagioclase as the major

minerals. Dominant features of these complexes are layered intrusions, flow

structures, magmatic enclaves and mingling/ mixing textures (Fig. 11). The

majority of contacts between intrusive varieties indicate contemporaneous

crystallization.

The Conuma River locality also displays ultramafic units that are

apparently rare within the Island Plutonic Suite (DeBari et al. 1999) and where

present and studied have usually been assigned to the Westcoast Crystalline

Complex (DeBari et al. 1999; Isachsen 1986; Larocque 2008). The CRIC and

31

Figure 11. Summary of field observations. A-D: Flow structures. E-H: Contacts. I: Magma (thorough) mingling textures. J, K: Magma mingling textures. L: Magma mixing textures.

32

LCIC have been assigned to the Island Plutonic Suite based on the absence of

gneissic foliation in the study area and the fact that the intrusions intrude the

Karmutsen Formation. However, the author is aware of the difficulties in

distinguishing between the Island Plutonic Suite and Westcoast Crystalline

Complex based on field observations.

The CRIC exhibits a distinctive layered structure, which has a number of

analogies worldwide. Alternating ultramafic and mafic sheets have been

interpreted as layered (stratiform) gabbroic intrusions, formed by in-situ

fractionation and/or multiple magmatic pulses (Irvine 1987, 1982; McBirney and

Noyes 1979; Boudreau and McBirney 1997; Jackson 1971; Conrad and Naslund

1989; Vuori and Luttinen 2003; Burns 1996, 1983; Goode 1976); composite

layering of bimodal gabbro-diorite complexes formed by basaltic magma

replenishments into silicic magma chambers (Lindline et al. 2004; Chapman and

Rhodes 1992; Wiebe 1988, 1993,1994); layered dykes owing their layered

appearance to marginal heat loss and formation of “congelation” cumulates or

to multiple injections (McCall 1971; Sethna et al. 1999); layered sills formed by

in-situ fractionation and differentiation into ultramafic and mafic layers due to

gravity settling of early formed dense ferromagnesian phases and floating of

plagioclase (Raudsepp and Ayres 1982; Sisson et al 1996); layered intrusions

formed due to flow differentiation (Bhattacharji 1967; Goode and Krieg 1967;

Nkono et al. 2006; Callot et al. 2001; DeBruiyn et al. 2000). The CRIC layered

structure is interpreted here as being formed by multiple pulses of hornblenditic

33

crystal mushes exploiting the sub-parallel, densely spaced fractures in the

solidifying intrusive host of hornblende gabbro/ hornblende diorite and tonalite.

Flow structures in the form of convoluted layers, lenses, wavy and flaser

layers, wispy and streaky features within a layered structure can result from

magmatic flow (Irvine 1980; Wadsworth 1994; Zak et al. 2007; Paterson et al.

1989, 1998; Springer 1980; Abbot 1989), tectonic flow (Paterson et al. 1989), or

a combination of both (Paterson et al. 1989, 1998; Hibbard 1987). Flow

structures in the CRIC layered intrusions are interpreted as a product of a

magmatic flow in combination with short-lived shear. Clear evidence of tectonic

flow (i.e. solid state flow) in form of mylonitic microstructures, ribbon quartz,

shear bands or anastomozing foliation (Vernon et al. 1988) was not observed.

Flow structures elsewhere in the CRIC and LCIC are also interpreted as products

of magmatic flow. Flow structures elsewhere in the area are defined by aligned,

elongate magmatic enclaves as in Vernon et al. (1988) and Blundy and Sparks

(1992).

Magmatic enclaves are common features in both complexes. Their origin

is somewhat controversial and has been interpreted by other workers as

representing basaltic injections, assimilated country rock, restites and cognate

fragmental blocks of cumulate material (Vernon 1983; Barbarin and Didier 1991;

Didier 1987; Didier and Barbarin 1991). In the CRIC and LCIC two major types of

mafic enclaves are interpreted to be of magmatic origin. The first type includes

coarse- to medium-grained ultramafic and mafic enclaves displaying no chill

textures against the host intrusions. Such enclaves could represent earlier

34

ultramafic to mafic magmatic pulses into the host tonalite. These magmas would

have sufficient time for partial crystallization, when subsequent emplacement of

new hot basaltic pulses into the host tonalite would cause partial melting of

tonalite and induce flow in the tonalite. The already partly solidified mafic and

ultramafic enclaves would become dismembered by destructive flow within the

host tonalite intrusion. The second type includes mafic enclaves derived by

injections of basaltic melt and crystal mushes that chilled against the cooler host

magmas. A number of locations worldwide exhibit this type of mafic enclave and

associated flow structures. Both types of magmatic enclaves are interpreted as

basaltic injections into solidifying host intrusions that were partially melted and

remobilized due to heat supplied by numerous pulses of hot basaltic magma

(Frost and Mahood 1987; Lindline et al. 2004; Dorais et al. 1990; Wiebe et al.

2004; Reid et al. 1983).

Magma mixing and mingling are believed to be a common and widespread

process operating and controlling compositions of magmas (Conrad et al. 1983;

Wiebe 1980, 1974; Wiebe et al. 2002, 1997; Asrat et al. 2003). Rheology of mafic

and silicic magmas and their ability to mingle and mix has been deduced from

field evidence, experimental work and rheologic modeling (McBirney 1980; Frost

and Mahood 1987; Sparks and Marshall 1986; Grammatikopoulos et al. 2007).

Magma mingling textures are distinctive features of both complexes and

are characterized by the presence of xenocrysts or clots of basaltic magma in

silicic magma or vice versa, with or without a disequilibrium reaction rim. Mingling

would likely take place during and after the emplacement of magmas into the

35

host intrusion. Mixing is interpreted from the presence of plagioclase crystals in

chilled mafic enclaves that could have been entrained from a host tonalite

magma. Mixing is expected to take place mostly prior to, but also during the

emplacement of magmas into the host intrusion.

36

4: PETROGRAPHY

The Conuma River and Leagh Creek intrusive complexes show a variety

of plutonic rock types. This chapter contains macroscopic and microscopic

description of three hornblendites, three hornblende gabbros, three hornblende

diorites and two tonalitic varieties. They are listed in order from ultramafic to

felsic compositions. Detailed microscopic analyses and additional

microphotographs are included in Appendix 2: Petrography. The textural and

modal variations of the representative intrusive rock types described in this

chapter are visually summarized in eight simplified sketches of textures (Fig. 12).

Of note, hornblendites and hornblende gabbros of the layered structure resemble

cumulates4.

4.1 Olivine hornblendite

Olivine hornblendite in outcrop is typically very coarse-grained and

holomelanocratic with rusty-brown weathering and black to dark green fresh

surfaces, consisting of interlocking (max. 10 mm) stubby dark green to grey and

brown hornblende megacrysts intergrown with (max. 3 mm) flakes of light brown

phlogopite. Allotriomorphic, light grey to green, 0.5 to 1 mm olivine and pyroxene

are included within hornblende megacrysts.

4 Cumulate is "an igneous rock characterized by a framework of contacting mineral crystals and

grains that evidently were concentrated through fractional crystallization of their parental magmatic liquids. Not all crystals need to be in contact. Fractional crystallization commonly yields rocks in which the mineral grains appear to have settled, whether they have or not" (Irvine 1982).

37

Figure 12. Schematical petrographical summary of modal and textural variations in rock types from intrusive complexes. White large crystals are hornblende megacrysts/phenocrysts; White specks in hornblende megacrysts/phenocrysts are plagioclase inclusions; striped crystals are tabular plagioclase phenocrysts; light green specks in hornblende megacrysts are olivine grains; relict clinopyroxene in hornblende are medium green; orthopyroxene is dark green; plagioclase clouds are yellow and phlogopite is brown; green background colour represents medium- to fine-grained groundmass consisting of 90-100% hornblende; blue background colour represents coarse- to fine-grained plagioclase-hornblende groundmass with 10-90% plagioclase with an exception of tonalite (H). A: Olivine hornblendite (one hornblende megacryst shows representative proportions of included minerals; representative proportions of interstial phases are also shown). B: Hornblendite with abundant hornblende megacrysts. C: Hornblendite with a limited number of hornblende megacrysts. D: Medium- to fine-grained equigranular hornblendite. E: Hornblende gabbro with hornblende megacrysts and plagioclase pheno-/xenocrysts. F: Hornblende gabbro/hornblende diorite with pheno-/ xenocrysts of hornblende and plagioclase. G: Hornblende gabbro/hornblende diorite with plagioclase pheno-/xenocrysts. H: Equigranular hornblende gabbro/hornblende diorite or tonalite (in the case of tonalite, the blue colour represents plagioclase-quartz groundmass).

38

In thin section, the olivine hornblendite is a holocrystalline, hypidiomorphic

inequigranular rock composed of 35% hornblende, 20% olivine, 15%

orthopyroxene, 10% plagioclase, 6% chlorite after phlogopite and orthopyroxene,

5% phlogopite, 5% relict clinopyroxene and 4% opaques (including spinel group

minerals and sulphides: Fe-hercynite, magnetite, Cr-magnetite, Ti-Cr magnetite,

Al-Cr magnetite, pyrite, chalcopyrite and pentlandite).

The texture is characterized by interlocking zoned hornblende oikocrysts

enclosing partly embayed olivine, plagioclase and minor irregular patches of

fresh clinopyroxene, spinels and sulphides (Fig. 13A). Orthopyroxene forms

larger grains, sometimes containing olivine grains in sharp or gradational contact

with hornblende, phlogopite and chlorite psuedomorphing phlogopite (Fig. 13B,

C). Interstices between hornblende megacrysts are filled with phlogopite and

chlorite after phlogopite. These interstitial phases contain embayed olivine, small

idiomorphic hornblende crystals and blebby inclusions of iron oxides.

4.2 Megacrystic hornblendite

Megacrystic hornblendite (i.e. hornblendite with megacrystic hornblende)

in outcrop is typically holomelanocratic with grey to green weathering, grey to

green fresh surfaces, consisting of hornblende megacrysts in medium-grained

“groundmass” of interlocking black to dark green hornblende, light brown biotite,

chlorite after biotite and whitish plagioclase. Hornblende megacryst (max. 10

mm) abundance varies from 5-90%, and they contain up to 20% inclusions of

light green pyroxene and olivine and grey plagioclase. The megacrystic

39

hornblendite can be difficult to distinguish from very coarse-grained olivine

hornblendite.

In thin section, the megacrystic hornblendite is a holocrystalline,

hypidiomorphic inequigranular rock. The texture of the “groundmass” is

dominantly equigranular with 90-60% 1-2 mm, allotriomorphic, fresh, green

hornblende, 10-40% hypidiomorphic plagioclase that is heavily altered to

sausserite, sericite, and minor interstitial biotite, partially to completely replaced

by chlorite (Fig. 13D). The “groundmass” hornblende can contain 1-10%

plagioclase inclusions and ~2% relict ferromagnesian minerals. The hornblende

megacrysts enclose 15% plagioclase, 10% orthopyroxene, 5% relict olivine and

clinopyroxene and 5% Fe-hercynite, Cr-magnetite, pyrite, and chalcopyrite

inclusions (Fig. 13E).

4.3 Hornblendite

Hornblendite in outcrop is typically medium-grained and melanocratic with

light grey to green weathering and grey to green fresh surfaces, consisting of

randomly oriented, interlocking, prismatic, black, 4 mm hornblende, prismatic

plagioclase and platy, light brown, 1 mm biotite. Hornblende may contain relicts

of ferromagnesian minerals and plagioclase inclusions.

In thin section, the hornblendite is a holocrystalline, hypidiomorphic

inequigranular rock composed of 60% hypidiomorphic, interlocking hornblende

crystals, 20% biotite, 12% plagioclase, 5% relict ferromagnesian minerals, 3%

magnetite and rare pyrite (Fig. 13F).

40

Figure 13. Photomicrographs of hornblendites. A: Olivine hornblendite-poikilitic brown hornblende (b hbl) and green hornblende (g hbl) enclosing fresh, partly resorbed olivine (ol) and orthopyroxene (opx), relicts of clinopyroxene (cpx) and sausseritized plagioclase (pl). Green spinel (spl) occurs in association with plagioclase and hornblende. Phlogopite (phl) is in sharp contact with hornblende (cross-polarized light). B: Olivine hornblendite-resorbed olivine (ol) enclosed by orthopyroxene (opx) overgrowth separated from enclosing hornblende (b hbl) by anthophyllite (ath) (cross-polarized light). C: Olivine hornblendite-orthopyroxene (opx) grain in sharp contact with phlogopite (phl) (dashed arrow), separated from green hornblende (g hbl) by colourless jigsaw rim of anthophyllite (ath). Fresh, resorbed olivine (ol) and orthopyroxene enclosed in brown hornblende (b hbl), phlogopite and chlorite (chl), and small euhedral green hornblende grains (sg hbl) enclosed in phlogopite and chlorite (plane polarized light). D: Megacrystic hornblendite-a medium-grained groundmass composed dominantly of interlocking hornblende (hbl) containing minor plagioclase inclusions (pl) (cross-polarized light). E: Megacrystic hornblendite-poikilitic hornblende (b hbl) megacryst encloses calcified relicts of ferromagnesian minerals: olivine (ol) and sausseritized (dashed arrow) and fresh resorbed plagioclase (pl) (cross-polarized light). F: Hornblendite-interlocking hornblende crystals show brown-green cores (b hbl) and green-bluish outer zones (g hbl), and contain cloudy plagioclase inclusions (pl). Chlorite (chl), biotite (bt) and sausseritized plagioclase (pl) occur in between hornblende crystals. Anthophyllite (ath) forms a fibrous margin of hornblende grains and most likely represent the contact between hornblende and ferromagnesian phases completely replaced by chlorite (plane polarized light).

41

4.4 Hornblende gabbro

Hornblende gabbro is typically medium-grained and mesocratic with

rusty-green weathering, grey to green fresh surfaces, consisting of creamy

weathering plagioclase crystals intergrown with green hornblende. Some

plagioclase grains show weak planar alignment.

In thin section, the hornblende gabbro is a holocrystalline, hypidiomorphic,

inequigranular, coarse- to medium-grained rock with 45% hornblende, 32%

plagioclase, 15% chlorite after hornblende, pyroxene and biotite, 2% calcite, 2%

apatite and 1% opaques (magnetite, iron oxide, sulphides and sphene).

The texture is characterized by poikilitic hornblende megacrysts enclosing

small, partly resorbed plagioclase crystals and relicts of ferromagnesian minerals

(Fig. 14A). The poikilitic hornblende grades into hornblende that is interstitial to

idiomorphic, medium-grained plagioclase grains. The interstitial hornblende and

medium-grained plagioclase tabullae form the equigranular, medium-grained

groundmass (Fig. 14B). Plagioclase phenocrysts are randomly distributed in the

groundmass.

4.5 Quartz hornblende gabbro

Quartz hornblende gabbro in outcrop is typically coarse- to medium-

grained and leuco- to mesocratic with light green to pink creamy weathering,

green to white fresh surfaces, consisting of brownish and bluish green

hornblende, randomly oriented white plagioclase tabullae distributed individually

or in 3 mm clusters, and yellowish flakes and books of biotite.

42

In thin section, the quartz hornblende gabbro is a holocrystalline,

hypidiomorphic, inequigranular rock with 30% hornblende, 50% plagioclase, 10%

biotite after hornblende, 5% quartz, 2% calcite, 2% apatite, and 1% opaques

(magnetite, iron oxide, sulphides and sphene). Poikilitic hornblende megacrysts

contain plagioclase inclusions, patchy clinopyroxene relicts, fresh and altered

orthopyroxene and olivine relicts (Fig. 14C). The groundmass is composed of

coarse- to medium-grained plagioclase with interstitial medium-grained

hornblende and quartz (Fig. 14D). Plagioclase phenocrysts are common.

4.6 Plagioclase hornblende gabbro porphyry

Plagioclase hornblende gabbro porphyry is typically fine- to medium-

grained and melanocratic with grey to green fresh and weathering surfaces,

consisting of black hornblende and gray plagioclase. It can contain up to 15%

plagioclase phenocrysts in a fine- to medium-grained groundmass composed of

65% hornblende and 20% plagioclase.

In thin section, the plagioclase hornblende gabbro porphyry is a

holocrystalline, hypidiomorphic, inequigranular rock with 47% hornblende, 35%

plagioclase, 10% quartz, 5% chlorite, 3% biotite and minor apatite. The texture is

dominated by an equigranular groundmass (Fig. 14E) consisting of idio- to

hypidiomorphic hornblende and plagioclase grains, interstitial quartz and

plagioclase phenocrysts (Fig. 14F).

43

Figure 14. Photomicrographs of hornblende gabbros. A: Hornblende gabbro-brown poikilitic hornblende megacryst (b hbl) enclosing sausseritized partly resorbed plagioclase (pl) (dashed arrows) and clinopyroxene relicts (cpx). A hornblende megacryst is in contact with plagioclase phenocryst (pl) in lower right (cross- polarized light). B: Hornblende gabbro-medium-grained plagioclase (pl)-hornblende (hbl) groundmass. Plagioclase grains have sausseritized cores (dashed arrows). Hornblende grains show recrystallization textures (cross-polarized light). C: Quartz hornblende gabbro-brown poikilitic hornblende (b hbl) enclosing colourless-dirty plagioclase (pl), brown relicts of olivine (id = iddingsite), fresh pink orthopyroxene (opx) and light green relicts of clinopyroxene (cpx) (plane polarized light). D: Quartz hornblende gabbro-coarse-grained plagioclase groundmass showing dominantly euhedral plagioclase (pl) and interstitial hornblende (hbl) and quartz (qtz) (cross-polarized light). E: Plagioclase hornblende gabbro porphyry-medium- to fine-grained, equigranular groundmass of euhedral bluish-green hornblende (hbl), subhedral sausseritized (clouded) plagioclase (pl) and interstitial colorless quartz (qtz). Hornblende cores (b hbl) are replaced by brown biotite and green chlorite (plane polarized light). F: Plagioclase hornblende gabbro porphyry-plagioclase phenocryst (pl) containing blebby hornblende inclusions (g hbl), and eutaxially intergrowths with plagioclase (plane polarized light).

44

4.7 Hornblende diorite

Hornblende diorite in outcrop is typically medium-grained and melano- to

mesocratic with black to green and rusty white weathering and dark green to

white fresh surfaces, consisting of prismatic, green hornblende, tabular, white

plagioclase, grey, interstitial quartz, light brown biotite enclosed in hornblende,

and light green actinolite.

In thin section, hornblende diorite is a holocrystalline, hypidiomorphic,

equigranular rock with 55% hornblende, 30% plagioclase, 7% quartz, 5%

chlorite, 3% biotite and 1% magnetite. Characteristically the texture is formed by

intergrowths of coarse-grained, idiomorphic hornblende and plagioclase with

quartz and plagioclase filling interstices between grains (Fig. 15A). Rare

plagioclase phenocrysts are present (Fig. 15B).

4.8 Spotted hornblende diorite

Spotted hornblende diorite in outcrop is typically medium-grained and

mesocratic with black spots in creamy white groundmass on weathered surfaces

and black to dark green spots in white groundmass on fresh surfaces. The

groundmass consists of green hornblende occurring as spots and as fine- to

medium-grained groundmass with whitish plagioclase and gray interstitial quartz.

Magnetite is a minor phase in the groundmass. Hornblende spots range from 2-

10 mm in diameter, depending on grain size and variety of the intrusive unit. The

abundance of spots ranges from 20-50% of the rock mode. Tabular, 5 mm

plagioclase phenocrysts occur in medium-grained varieties of spotted hornblende

diorite and comprise 5% of the rock mode.

45

In thin section, the spotted hornblende diorite is a holocrystalline,

hypidiomorphic to idiomorphic, inequigranular rock with 55% hornblende, 35%

plagioclase, 5% quartz and 5% magnetite. The texture is characterized by

hypidiomorphic, poikilitic hornblende spots embedded in a fine- to medium-

grained idio- and hypidiomorphic hornblende-plagioclase-magnetite groundmass

(Fig. 15C). Hornblende spots can be single, large hornblende grains, or clusters

of 3-4 medium-grained hornblende grains, and contain anhedral, resorbed

plagioclase inclusions. Medium-grained plagioclase appears to grow from the

groundmass into the hornblende spots (Fig. 15D). Occasional tabullae of

plagioclase phenocrysts occur in the groundmass.

4.9 Acicular hornblende diorite

Acicular hornblende diorite is typically fine-grained and mesocratic with

light grey to white weathering and medium grey fresh surfaces, consisting of

acicular-tabular white plagioclase and acicular dark green hornblende with ≤ 6

mm long needles. The needle length may decrease from the centre to the margin

of a mafic enclave and eventually grade into a dark green to black aphanatic

mass. The mafic enclaves can also contain xenocrysts from surrounding tonalite.

The xenocrysts include 2-3 mm plagioclase, 2 mm quartz, 2 mm hornblende, and

reaction rims around the xenocrysts can be present. The reaction rims have

small hornblende crystals eutaxially aligned at the margin of the xenocryst. Also

common are feldspar reaction rims on quartz grains and clots of quartz and

plagioclase enclosed within the groundmass of the mafic enclave.

46

In thin section, the acicular hornblende diorite is a holocrystalline,

idiomorphic equigranular rock with 35% plagioclase, 25% hornblende, 20%

quartz, 15% biotite, 5% magnetite and apatite and 0-10% xenocrysts (quartz and

plagioclase). Characteristic texture shows intergrowth of equigranular grains of

hornblende, plagioclase and quartz (Fig. 15E), with occasional plagioclase and

quartz xenocrysts or phenocrysts (Fig. 15F). Plagioclase contains abundant

apatite needles. The texture resembles the groundmass texture of the spotted

hornblende diorite.

4.10 Tonalite

Tonalite in outcrop is typically medium-grained and leucocratic with

creamy weathering and white to grey fresh surfaces, consisting of white

plagioclase, light grey quartz and chloritized biotite and chloritized hornblende.

In thin section, the tonalite is a holocrystalline, hypidiomorphic

equigranular rock composed of 44% plagioclase, 44% quartz, 10% biotite, 1%

hornblende and 1% chlorite. The dominant texture is defined by interlocking,

equigranular plagioclase and quartz crystals (Fig. 16A, B).

4.11 Trondhjemite

Trondhjemite in outcrop is typically medium-grained and hololeucocratic

with white to light grey weathering and light grey fresh surfaces, consisting of

white feldspar tabullae interlocked with light grey quartz and brown to green

biotite and hornblende almost completely altered to chlorite. Graphic texture can

be sometimes observed in quartz grains on a fresh surface of a handspecimen.

47

Figure 15. Photomicrographs of hornblende diorites. A: Hornblende diorite-diamond shaped brown hornblende (hbl) crystals with biotitized and chloritized cores (dashed arrows). The hornblende grains are in contact with interstitial plagioclase (pl) and quartz (qtz) (cross-polarized light). B: Hornblende diorite-example of a plagioclase phenocryst (pl). Solid arrow points to eutaxial intergrowth of hornblende (hbl) with plagioclase (pl). Phenocryst displays partly resorbed core and zones (dotted arrows). About 20% of phenocryst is sausseritized and sericitized (dashed arrow) (cross-polarized light). C: Spotted hornblende diorite-two spotted hornblende oikocrysts/glomerocrysts in a fine- to medium-grained hornblende (hbl)-plagioclase (pl)-magnetite (mag) groundmass (dotted arrows). Hornblende spots are chloritized and contain plagioclase (pl) inclusions (plane polarized light). D: Spotted hornblende diorite-a poikilitic hornblende spot (hbl) partly (dashed arrow) and fully (solid arrows) enclosing plagioclase inclusions (pl) of different sizes (cross-polarized light). E: Acicular hornblende diorite-characteristic texture of mafic enclave in tonalite showing equigranular grains of green hornblende (hbl) partly replaced by biotite, plagioclase (pl) with sausseritized calcic core and interstitial quartz (qtz) with minor equigranular magnetite (mag) (plane polarized light). F: Acicular hornblende diorite-quartz (qtz) xenocryst with hornblende (hbl) reaction rim. Opaque primary phase is magnetite (mag) (plane polarized light).

48

In thin section, the trondhjemite is a holocrystalline, hypidiomorphic

equigranular rock composed of 47% plagioclase, 45% quartz, 5% biotite, 3%

hornblende and 1% sphene, magnetite and ilmenite. The texture is characterized

by interlocking crystals of equigranular, idio- to hypidiomorphic plagioclase with

allotriomorphic quartz that also occur in vermicular intergrowths (Fig. 16C, D).

Also present are rare, idiomorphic magnetite grains. Rare relicts of

ferromagnesian minerals as inclusions in hornblende are distinctive and

resemble xenocrysts (Fig. 16E, F).

4.12 Metamorphic assemblages

Low grade, greenschist facies rocks are found throughout the area, which

include metamorphic assemblages represented by chlorite, epidote (in the form

of lenses between chlorite and biotite cleavages), and actinolite.

4.13 Alteration assemblages

Alteration assemblages include complete to partial deuteric alteration of

clinopyroxene replaced by hornblende, and hornblende replaced by biotite,

fibrous anthophyllite replacing ferromagnesian phases at their margins, and

chlorite after orthopyroxene and phlogopite. Olivine altered partly and/or

completely to serpentine, iddingsite, calcite, chlorite and iron oxides. Plagioclase

altered partly and/or completely to sausserite and sericite.

49

Figure 16. Photomicrographs of tonalites. A: Tonalite-characteristic texture consisting of interlocking plagioclase (pl) and quartz (qtz). The plagioclase varies in size. Bigger plagioclase crystals show partial resorption of the cores and zones (dotted arrows). The plagioclase is partly altered to sausserite and sericite (dusty-looking crystal areas) (cross-polarized light). B: Tonalite-biotite (bt) is fresh and the only primary ferromagnesian phase, usually surrounded by quartz (qtz) (in plane polarized light). C: and D: Trondhjemite-dashed arrows point to vermicular intergrowths of quartz (qtz) and plagioclase (pl) (plane and cross-polarized light retrospectively). E: Trondhjemite- xenocrysts of relict ferromagnesian minerals (arrows) are rare and occur within chlorite after biotite. Sausseritized and sericitized plagioclase (pl) and interstitial quartz (qtz) are present (plane polarized light). F: Trondhjemite-a detailed view of a relict of ferromagnesian phase from E (solid arrow). Dotted arrow points to reaction rim (cross-polarized light).

50

4.14 Microstructures

The most common microstructures in all representative varieties include

kinked biotite and chlorite. Other deformation structures are microfaults and

microfractures in plagioclase of the spotted hornblende diorite, in hornblende and

anthophyllite of the hornblendites, and in quartz and plagioclase in tonalite in

contact with megacrystic hornblendite. Recrystallization of hornblende and some

plagioclase is present in sheeted hornblende gabbros and megacrystic

hornblendite at the contact with tonalite.

51

5: MINERALOGY

Mineral chemistry was obtained from olivine, pyroxene, hornblende,

plagioclase, mica and oxide grains from olivine hornblenditic and hornblende

gabbroic sheets of layered intrusions from the Conuma River intrusive complex

(Appendix 3: Tables A3-1-8).

1/ Olivine from olivine hornblendite sheets:

Unzoned olivine is chrysolite: Fo80.1 (DM05-212A) and Fo78.6 (KF07-E1 and

JN1). Core to rim traverses within olivine grains shows no consistent variation in

trend. Ni and Cr increase and Fe and Mg decrease with respect to an increase in

silica. EDS analyses of probed grains are consistent with analysis of olivine

grains from other olivine hornblendite sheet (KF07-Q2), with no available

microprobe data.

2/ Pyroxenes from olivine hornblendite, hornblende and quartz hornblende

gabbroic sheets:

Unzoned orthopyroxene from two olivine hornblendite sheets is bronzite:

En81.3 (DM05-212A) and En81 (KF07-JN1). Unzoned orthopyroxene from quartz

hornblende gabbro sheet is bronzite: En79.7 (KF07-JN3). Unzoned clinopyroxene

from hornblende and quartz hornblende gabbro sheets is diopside:

Ca48.2Mg44.6Fe7.2 (KF07-JN3) and Ca48.7Mg42.9Fe8.4 (DM05-212C). A core to rim

traverse shows no consistent variation in trend. Mg decrease and Fe increase

52

correlate well with a slight silica increase. Titanium increases with silica in

orthopyroxene, but it behaves oppositely in clinopyroxene.

The EDS analyses of probed bronzite are consistent with the EDS of

orthopyroxene from other olivine hornblendite sheets (KF07-E1 and Q2). Due to

very small grain size and abundant alteration, no data on clinopyroxene

composition were obtained from microprobe analyses. Additionally, EDS of relict

clinopyroxene were collected from three olivine hornblendite sheets. The results

are consistent with diopsidic clinopyroxene.

3/ Hornblende from olivine hornblendite, hornblende and quartz-

hornblende gabbroic sheets:

Hornblende crystals in all samples are zoned. Compositional variations

exist between hornblende grains within a single thin section (Fig. 17). The EDS

analyses of hornblende grains from the other olivine hornblendite sheet (KF07-

Q2) are similar to the EDS data of probed hornblende grains. Core to rim

traverses within brown and green zones show no consistent variation trend.

Using Leake et al. (1997) nomenclature of amphiboles, most of the

hornblende grains are calcic hornblendes: pargasite and magnesiohastingsite

with no correlation to colour (Fig. 18; Appendix 3: Fig. A3-1). Fibrous and

colourless amphibole (in PPL) plots in anthophyllite field.

Brown hornblende from all analyzed intrusive varieties appears to have

elevated Ti, K, Cr and Ca concentrations when compared to green hornblende.

Green hornblende from all analyzed intrusive varieties shows higher Al, Cl

53

0.001

0.01

0.1

1

10

212A-5 B

212A-7 B

212A-8 B

212A-9 B

212A-10 B

212A-1 G

212A-4 G

212A-11 G

212A-3 G

212A-12 MG

212A-14 MG

212A-15 MG

212A-16 MG

212A-22 SG

212A-23 SMG

Ox%(F )

Ox%(Na)

Ox%(Mg)

Ox%(Al)

Ox%(Si)

Ox%(Cl)

Ox%(K )

Ox%(Ca)

Ox%(Ti)

Ox%(Cr)

Ox%(Mn)

Ox%(Fe)

Points in hornblende grains

Ma

jor o

xid

es (

wt%

)

Point analyses of hornblende grains from olivine hornblendite

margin of a green zone in a megacrystbrown "core" of a megacryst green zone of a megacrystsmall grainC M

Figure 17. Point analyses in hornblende grains from the CRIC olivine hornblendite sheet show no correlation between variations in cores and margins. Abbreviations: 212A = DM05-212A; C = core; M = margin; B = brown-green; G = bluish-green.

0

0.5

1

4.55.56.57.5

212A G

212A B

212C B

A3 G

A4 G

A4 B

JN1 G

JN1 B

E1 G

Representative analyses of calcic hornblendes (diagram after Leake et al. 1997 )

pargasite

AlVI > Fe3+

magnesiohastingsite

AlVI < Fe3+

Mg

/(M

g+

Fe

2+)

Si in formula

edenite

ferro-edenite

ferro-pargasite

AlVI > Fe3+

hastingsite

AlVI < Fe3+

sadanagaite

magnesiosadanagaite

Figure 18. Representative analyses of calcic hornblendes from the CRIC layered intrusions. Hornblende grains plot in the pargasite-magnesiohastingsite field (after Leake et al. 1997: Ca > 1.50 and (Na+K)A). Abbreviations: 212A=DM05-212A, JN1= KF07-JN1, E1=KF07-E1-olivine hornblendites; A3=KF07-A3-megacrystic hornblendite; A4= KF07-A4, 212C=DM05-212C-hornblende gabbro; B=brown; G=green.

54

and Na concentrations than the brown hornblende (Fig. 19).

0.01

0.1

1

10

212A B JN1 B JN1 G E1 G 212A G

TiO2

Al2O3

Cr2O3

FeO

MnO

MgO

CaO

Na2O

K2O

F

Cl

Mg#

Compositional variations in hornblende megacrysts

from olivine hornblendite sheets

Silica increase ------>

Ma

jor o

xid

es (

wt%

)

Silica increase ------>

Differences in the brown hornblende compositions between intrusive varieties

exist, but are slight. The brown hornblende from the hornblendites show higher

Cr, Na and Mg than the brown hornblende from the hornblende gabbros (higher

Mn, K, Ti and Fe). The green hornblende in the hornblendites shows higher Na,

Al, Mg and Cl than the green hornblende in the hornblende gabbros (higher K, Ti,

Fe and Ca) (Fig. 20).

Figure 19. Compositional variation in the brown-green (B) and the bluish-green (G) hornblendes from three CRIC olivine hornblendite sheets. This plot can also be viewed as a virtual core-rim traverse from brown-green core (B) into an outer bluish-green zone (G) of a hornblende megacryst. The major difference between brown (B) and green (G) hornblende is the relatively elevated Ti concentration in brown hornblende (B), which also appears to be elevated in Cr and K. Aluminium and Cl are elevated in the green hornblende (G), as well as a slight increase in Na. The Mg# is higher in the green hornblende (G) (see Mineral paragenesis chapter). Abbreviations: 212A=DM05-212A, JN1=KF07-JN1, E1=KF07-E1.

55

0.01

0.1

1

10

100

212A B JN1 B A3 B A4 B JN3 B 212C B JN1 G E1 G 212A G A3 G A4 G 212C G

SiO2

TiO2

Al2O3

Cr2O3

FeO

MnO

MgO

CaO

Na2O

K2O

F

ClAveraged probe data from brown and green hornblende

Compositional variations in hornblende from olivine hornblendite,hornblende and quartz hornblende gabbro sheets

Ma

jor

oxid

es

(wt%

)olivine hornblendite olivine hornblenditehornblende gabbro hornblende gabbro

Figure 20. Compositional variation in the brown and green hornblende from hornblenditic and hornblende gabbro sheets of the CRIC layered intrusion. Abbreviations: B=brown; G=green; 212A=DM05-212A, JN1=KF07-JN1, E1=KF07-E1-olivine hornblendite; A3=KF07-A3-megacrystic hornblendite; A4=KF07-A4, 212C=DM05-212C-hornblende gabbro; JN3= KF07-JN3-quartz hornblende gabbro.

4/ Hornblende from four successive alternating hornblenditic and

hornblende gabbroic sheets:

Four successive sheets within a layered outcrop KF07-A are considered:

DM05-212A–olivine hornblendite; DM05-212C–hornblende gabbro; KF07-A3–

megacrystic hornblendite; and KF07-A4–hornblende gabbro. Titanium

consistently decreases and Cl and Fe increase from brown to green hornblende

in each of four sheets across the sequence. Hornblendite sheets across the

sequence show a consistent increase in Na and Al from brown to green

hornblende. Hornblende gabbro sheets across the sequence show a consistent

decrease in Na and Al from brown to green hornblende (Fig. 21).

56

0.01

0.1

1

10

100

212A B 212A G 212C B 212C G A3 B A3 G A4 B A4 G

SiO2

TiO2

Al2O3

Cr2O3

FeO

MnO

MgO

CaO

Na2O

K2O

F

Cl

Maj

or

oxi

des

(w

t%)

Compositional differences between brown and green hornblende from four successive sheets of alternating olivine hornblendite abd hornblende gabbro

Averaged probe data from brown and green hornblende

Potassium and Fe increase in all brown hornblende across the sequence,

while green hornblende shows only a slight increase of K (Fig. 22).

0.01

0.1

1

10

100

212A B 212C B A3 B A4 B 212A G 212C G A3 G A4 G

SiO2

TiO2

Al2O3

Cr2O3

FeO

MnO

MgO

CaO

Na2O

K2O

F

Cl

Compositional variations in hornblende from four successive sheets of alternating olivine hornblendite and hornblende gabbro

Averaged probe data from brown and green hornblende

Maj

or

oxi

des

(w

t%)

Figure 22. Compositional variations in brown (B) and green (G) hornblende grains across four successive layers within a sheeted intrusion of the CRIC. Only K concentration increases slightly across the sheets in both types of hornblende. Abbreviations: 212A=DM05-212A-olivine hornblendite; 212C=DM05-212C–hornblende gabbro; A3=KF07-A3–megacrystic hornblendite; A4=KF07-A4–hornblende gabbro.

Figure 21. Compositional variation in brown (B) and green (G) hornblende from four successive sheets of alternating hornblendites and hornblende gabbros of the CRIC. Trends in Ti decrease whereas Fe and Cl increase from brown to green hornblende in each sheet. Abbreviations: 212A=DM05-212A–olivine hornblendite; 212C=DM05-212C–hornblende gabbro; A3=KF07-A3–megacrystic hornblendite; A4=KF07-A4–hornblende gabbro.

57

5/ Feldspar from hornblendite, hornblende and quartz hornblende gabbro,

hornblende diorite, tonalite and trondhjemite intrusions:

Compositions of feldspar grains were obtained either by microprobe, EDS

and Michel-Levy method or by combination of these analyses (Fig. 23).

Figure 23. Graphic representation of plagioclase compositions (% An content) obtained by microprobe, EDS and Michel-Levy method. Plagioclase occurs commonly in three forms: pheno-/xenocryst, inclusions and groundmass. Phenocrysts contain zones of different compositions (+Qtz = quartz-plagioclase intergrowth in the core of phenocryst)

58

Feldspar composition within a single thin section varies from An90 to An20

(Fig. 24).

20

30

40

50

60

70

80

90

212C

gm&ppx

212C

gm

212C

gm

212C

gm

A4

incl

A4

incl

An %

Compositional variations in feldspar from two hornblende gabbro sheets

Averaged point analyses of feldspar grains

Two types of plagioclase phenocrysts from a quartz hornblende gabbro

were observed within a single thin section. The plagioclase phenocrysts (PPX 1)

show plagioclase (An45.5) intergrowth with quartz in the core. The adjacent zone

has an An41.2 content and changes into a highly calcic zone (An89.5). Two outer

zones fall back to An45.5 and are overgrown by a quartz rim. All zones show

partial resorption (Figs. 25 and 26).

The second type of plagioclase phenocryst (PPX 2) consists of highly

calcic core (An85.8) surrounded by an An49.5 zone, which changes into a highly

calcic zone rimmed by an An49 zone. All zones show partial resorption (Figs. 27

and 28).

Figure 24. Variations in An component in plagioclase from two hornblende gabbro sheets (212C=DM05-212C and A4=KF07-A4; gm=groundmass plagioclase; ppx=plagioclase phenocryst; incl=plagioclase inclusion in hornblende oikocryst).

59

Figure 25. Plagioclase phenocryst in a quartz hornblende gabbro. The plagioclase phenocryst is graphically intergrown with medium grey quartz and red-brown hornblende in cross-polarized light. Probe data reveals average andesine compositions. Details of the traverse are shown in Fig. 26.

0

20

40

60

80

100

Z1 Z2 Z3 Z4 Z5 Z6

Ox%(Na)

Ox%(Mg)

Ox%(Al)

Ox%(Si)

Ox%(K )

Ox%(Ca)

Ox%(Mn)

Ox%(Fe)

Ox%(Ba)

Traverse of plagioclase phenocryst - PPX 1

Point analyses of zones in plagioclase phenocryst

core rim

Ma

jor o

xid

es (w

t%)

Figure 26. Core to rim traverse across the plagioclase phenocryst PPX 1 from quartz hornblende gabbro. Sodic plagioclase intergrowth occurs in the core, followed by an increase in sodic component and then a calcic zone. The outer rim is composed of sodic plagioclase and quartz.

60

0

10

20

30

40

50

60

Z1 Z2 Z3 Z4

Ox%(Na)

Ox%(Mg)

Ox%(Al)

Ox%(Si)

Ox%(K )

Ox%(Ca)

Ox%(Mn)

Ox%(Fe)

Ox%(Ba)

Traverse of plagioclase phenocryst - PPX 2

Point analyses of zones in plagioclase phenocrysts

Ma

jor o

xid

es (w

t%)

core rim

Figure 28. Traverse across plagioclase phenocryst PPX 2 from a quartz hornblende gabbro sheet. Calcic plagioclase occurs in the core, followed by a sodic-calcic zone and then a calcic zone. The outer rim is composed sodic-calcic plagioclase.

6/ Mica from hornblenditic and hornblende gabbroic sheets:

Based on Fe:Mg ratios, mica from hornblendites falls into a phlogopite

field. The phlogopite from three hornblendites shows a slight decrease in K and

an increase in Na with respect to a relative silica increase. EDS of mica with no

microprobe data resemble EDS from probed phlogopite.

Figure 27. Quartz hornblende gabbro. Two plagioclase phenocrysts show compositional variations along the traverse from core to rim. These plagioclase grains contain two calcic zones and at least two sodic-calcic zones. Compositional variations are shown in Fig. 28.

61

7/ Oxides from hornblenditic sheets:

Iron hercynite (green spinel) mineral chemistry was obtained from two

hornblenditic sheets. EDS were obtained from other oxides, which were identified

as titanomagnetite, chromian magnetite, Ti-Cr magnetite, Al-Cr magnetite and

magnetite. The quartz hornblende gabbro also contains an ilmenite phase.

8/ Magnesium numbers of mineral phases from hornblenditic sheets:

Magnesium numbers (Mg#) were calculated for olivine, orthopyroxene,

hornblende and phlogopite in an olivine hornblendite and quartz hornblende

gabbro sheets. The Mg# was calculated as Mg/ (Mg+Fe2+) and also as Mg/

(Mg+totalFe+Mn). Recalculation of total iron to estimate Fe2+ and Fe3+ content for

the purpose of naming the amphiboles followed the procedure described in

Leake et al. (1997). Calculated Fe2+ and Fe3+ concentrations in hornblende

grains show extreme variations in range from “all ferrous” to “all ferric”, which

significantly affects Mg# values (Fig. 29). Recalculation of total iron to estimate

Fe2+ and Fe3+ content in pyroxenes followed the procedure described in

Morimoto (1989). Total Fe = Fe2+ was assumed for olivine. The same approach

was applied to mica to get an approximate Mg#.

9/ Compositional variations in ferromagnesian phases from hornblendites

and hornblende gabbros:

Nickel is found within olivine and orthopyroxene, and less commonly in

clinopyroxene; Ni decreases in concentration in the following order: olivine-

orthopyroxene-clinopyroxene. Nickel is known to preferentially partition into

62

70

75

80

85

90

95

100

212A

ol

212A

opx

212A

B hbl

212A

G hbl

212A

mica

JN1

ol

JN1

opx

JN1

B hbl

JN1

G hbl

JN1

mica

E1

ol

E1

G hbl

E1

mica

JN3

opx

JN3

B hbl

JN3

mica

Mg/(Mg+total Fe+Mn)

Mg/(Mg+Fe2+)

Mg #

Samples

Mg numbers of minerals phases from olivine hornblendite and quartz hornblende gabbro sheets

Figure 29. Magnesium numbers (Mg#) of olivine (ol), orthopyroxene (opx), green hornblende (G hbl) and brown hornblende (B hbl) from three CRIC olivine hornblendite sheets (212A=DM05-212A; JN1=KF07-JN1; E1=KF07-E1) and one quartz hornblende gabbro sheet (JN3=KF07-JN3). Orange lines connect Mg# calculated as Mg/(Mg+Fe

2+). Blue lines connect Mg # calculated as

Mg/(Mg+totalFe+Mn). Values of Mg# differ significantly in hornblende.

63

olivine (Brown 1980), where it is the only phase with elevated Ni concentrations.

Chromium content increases gradually within the following minerals in ascending

order: olivine-orthopyroxene-clinopyroxene-green hornblende-brown hornblende.

Titanium and Na follow a similar path as Cr, but Na reaches a peak in the green

hornblende. Magnesium numbers are high in all phases. Manganese reaches

peak concentrations in the hornblendes, with a preference for the green

hornblende over the brown (Fig. 30).

0.0001

0.001

0.01

0.1

1

10

100

212A ol

212A opx

212A G hbl

212A B hbl

212A phlo

E1 ol

E1 G hbl

E1 phlo

JN1 ol

JN1 opx

JN1 G hbl

JN1 B hbl

JN1 phlo

JN3 opx

JN3 B hbl

JN3 phlo

Si

Ti

Al

Cr

Fe

Mn

Mg

Ca

Na

Ni

MG#

Compositional changes in mineral phases from olivine hornblendite and quartz hornblende gabbro sheets

Cat

ion

mo

lecu

lar

pro

po

rtio

n

Mineral phases in a thin section

Figure 30. Compositional changes in ferromagnesian mineral phases within olivine hornblendite (212A=DM05-212A; E1=KF07-E1 and JN1=KF07-JN1), hornblende gabbro (212C=DM05-212C) and quartz hornblende gabbro (JN3=KF07-JN3). General pattern dominates in all shown intrusive sheets. Ol=olivine, opx=orthopyroxene, G hbl=green hornblende, B hbl=brown hornblende, cpx=clinopyroxene, phlo=phlogopite and act= actinolite.

64

6: MINERAL PARAGENESIS

The mineral paragenesis for the hornblendites (olivine hornblendite,

megacrystic hornblendite and hornblendite), hornblende gabbros (hornblende

gabbro, plagioclase hornblende gabbro porphyry and quartz hornblende gabbro),

hornblende diorites (equigranular hornblende diorite, spotted hornblende diorite

and acicular hornblende diorite) and the tonalites (tonalite and trondhjemite) is

based on field relations, petrography and mineralogical analyses. The phase

crystallization steps are listed sequentially for each rock type.

6.1 Hornblendites

6.1.1 Olivine hornblendite

1/ Olivine-Olivine (Fo ~80) grains are interpreted to have crystallized first

(Fig. 31) because they occur as unzoned, rounded, partly resorbed and isolated

grains enclosed by orthopyroxene, hornblende and phlogopite. Resorption

textures in crystals can be produced by decompression, temperature increase,

temperature drop due to slow cooling, and elevated water concentration in melt.

A sudden temperature decrease will cause rapid growth of crystals, resulting in

dendritic, skeletal, boxy cellular crystal shapes, which can also resemble

resorption textures (Drever 1958). The olivine in the olivine hornblendite may

owe its resorbed appearance to magma ascent accompanied by decompression,

which caused a shift of the olivine subsolidus curve into the liquidus field.

65

Magma, carrying these olivine crystals, was emplaced at some point during its

ascent at conditions outside the olivine stability field and instead of crystallizing

olivine, orthopyroxene was the stable precipitate.

2/ Orthopyroxene-Orthopyroxene is interpreted to have been the second

phase to crystallize. It grew either preferentially on pre-existing olivine or

suspended in the melt. Orthopyroxene (En ~81) grains are unzoned, anhedral and

partly resorbed, and can be in sharp contact with hornblende. It is likely that

some of olivine grains reacted with the melt to form orthopyroxene, but most of

them are interpreted to have coexisted with orthopyroxene. Both olivine and

orthopyroxene have high Mg#, which is common for phases forming from melt

with a Mg-rich bulk composition. In Mg-rich melts, Fe-Mg partitioning between

olivine and orthopyroxene is relatively insensitive to pressure or temperature

(Brown 1980). It is likely that orthopyroxene in olivine hornblendite formed from

melt with elevated water content, and that the enstatite growth rate decreased

with decreasing temperature. These assumptions are based on experiments on

growth of enstatite showing that the nucleation rate for enstatite is greatly

reduced at lower pressures and for water contents of less than 0.1wt%. The

presence of water (1-5 wt%) enhances nucleation rates of enstatite, but has no

effect on growth rate (Yund 1991; 1997).

3/ Highly calcic plagioclase-Highly calcic plagioclase is interpreted to

be the third phase to crystallize. It forms rare fresh, unzoned, twinned, and partly

resorbed crystals surrounded by hornblende or heavily sausseritized “clouds”. Its

minor occurrence in the olivine hornblendite may indicate suppressed

66

crystallization of plagioclase, favouring crystallization of clinopyroxene due to

elevated water content in the melt. Its appearance is also consistent with the

reaction: plagioclase + melt = hornblende, which would contribute Al to magmatic

hornblende.

4/ Clinopyroxene-Clinopyroxene is interpreted to have crystallized

simultaneously with plagioclase or shortly after plagioclase. Relicts of

clinopyroxene, in the form of colourless patches in hornblende (in PPL), are in

contact with early mineral phases and suggest that clinopyroxene crystallized via

preferential nucleation on preexisting crystals and continuous growth around

them. At this crystallization stage a basaltic magma would contain poikilitic

clinopyroxene crystals either suspended within or in contact with orthopyroxene.

It is likely that clinopyroxene represents the last phase of a high temperature

mineral assemblage.

5/ Hornblende-Hornblende is the fifth mineral phase in the crystallization

order and exhibits two zones: brown and green. Based on the peaks of Ti, Cr and

Ca in the brown hornblende and peaks of Na, Fe and Cl in the green hornblende,

the brown hornblende is believed to form as subsolidus replacement of higher

temperature Ti-clinopyroxene, and the green hornblende represents partly

magmatic hornblende and partly subsolidus replacement of lower temperature Ti-

poor clinopyroxene. The brown hornblende is characterized by an elevated Ti

content, in contrast with lower Ti content in the green hornblende. Elevated Ti in

the brown hornblende is analogous to the high Ti concentration in hornblende

from the hybridized Sazava intrusions from Bohemia, central Europe, where the

67

hornblende is believed to be relicts of a higher pressure-temperature stage; with

temperature exceeding 900oC (Janousek et al. 2004). Janousek et al. (2004)

interpreted the hornblende to have formed as a part of an early high temperature

assemblage which was subsequently injected into shallower levels, where they

were overgrown by green amphibole.

The elevated concentrations of Cr within the brown hornblende could

indicate an early crystallized phase, such as Ti-clinopyroxene, and the Cr was

inherited from early Cr-bearing phases, which subsequently underwent

subsolidus reactions. Similar arguments, using the analogy of the formation of

Ca-enriched cores and Ca-poor rims in pyroxene (Deer et al. 1966), can be

derived from Ca-rich brown hornblende versus Ca-poor green hornblende.

Elevated Na, Fe and Cl content in green hornblende may indicate

formation of a magmatic hornblende -prior to solidus and subsolidus replacement

reactions- as a continuous growth on Ti-poor clinopyroxene from Na- and Fe-

enriched melt. Likewise, the Cl content in green hornblende can indicate that

magmatic green hornblende formed prior to the brown hornblende, perhaps from

a vapour-saturated melt. It is thought that Cl concentration decreases during the

evolution of a melt. High Cl content is preserved in phases forming from vapour-

undersaturated melts, whereas low Cl is expected in fractionated, evolved melts

that experienced the loss of volatiles (Conrad and Kay 1984). This may be the

case for the Cl-elevated green and Cl-poor brown amphibole forming late in the

paragenesis after considerable volatiles had exsolved from the evolved melts.

68

6/ Phlogopite-Phlogopite can be interpreted as the last major phase to

crystallize from the melt or maybe a product of subsolidus reactions due to alkali

metasomatism. In the former, the last interstitial melt was likely water and K-

enriched, and therefore, could result in crystallization of phlogopite. In the latter,

it cannot be excluded that phlogopite could be a subsolidus phase completely

replacing any of the hornblende.

Cores and rims of phlogopite do not show major compositional variations.

This is could be due to the ease of re-equilibrating Fe and Mg in sheets silicates

(Vernon 1991). In general, igneous micas can undergo many post-magmatic

changes affecting their mineral chemistry. Micas from plutonic rocks may be

more strongly affected than micas from volcanic rocks, due to a slow cooling

history (Speer 1984). This makes them difficult to use for reconstruction of

mineral paragenesis as late stage permeating fluids can cause post-magmatic

oxidation of some original Fe2+ (Speer 1984). The distribution coefficient (Kd) for

Fe-Mg partitioning between hornblende and biotite (from rocks of intermediate

compositions) is defined as:

hornblende

biotied

Mg

Fe

Mg

Fe

KMgFe

and ranges between 0.66 and 1.1.

Another study by Speer (1984) documents low values of distribution

coefficients for low pressure igneous rocks (Kd =0.6-0.7), and higher Kd values

for deeper-seated igneous bodies (Kd=0.8-0.9). The Kd from olivine hornblendites

ranges between 0.8-1.1, which may indicate coexistence of hornblende with

69

phlogopite at deeper-seated plutonic levels. However, Speer (1984) also reports

the opposite scenario, where lower Kd corresponds to higher pressure

crystallized rocks and vice versa. In the end, Speer concluded that Fe-Mg

partitioning is controlled by mineral chemistry of amphibole-biotite, which in turn

is controlled by whole rock geochemistry and not by physical conditions.

7/ Products of subsolidus reactions-Due to prolonged cooling,

metasomatism may have played an important role in the subsolidus genesis of

the olivine hornblendites. One of the dominant replacement reactions is pyroxene

replaced by hornblende. Clinopyroxene is commonly replaced by “uralitic”

amphibole, either by a single amphibole crystal, or as an aggregate of small,

prismatic amphibole crystals. The replacement preferentially starts from the

crystal margins and progresses along cleavages into the center of the pyroxene

crystal. Common products of this replacement are colourless patches of

clinopyroxene (Deer et al., 1966). One source of Al for the subsolidus

hornblende can come from pyroxene as it can contain 2 to 4 wt% Al2O3 (Deer et

al. 1966). Pyroxenes in olivine hornblendites contain on average 1.5 wt% Al2O3,

but an additional source of Al could be calcic plagioclase.

Alkali metasomatism may have occurred during the cooling of the

numerous crystallizing and differentiating intrusions. These could supply water-

and K-enriched exsolved fluids. The presence of subsolidus alteration

assemblage requires an additional input of water into olivine hornblendites

producing hornblende after clinopyroxene and olivine; serpentine, iddingsite and

chlorite after olivine; anthophyllite and chlorite after orthopyroxene; and chlorite

70

after phlogopite. It is probable that hornblende crystals owe their megacrystic

size to multiple metasomatic events.

Phases of the spinel group such as green spinel (Fe hercynite), Cr-

titanomagnetites and other varieties of magnetite also appear to be the products

of subsolidus reactions occurring during a long cooling period. Euhedral

magnetites in olivine can be produced by oxidation at 1000oC (Brown, 1980).

This does not appear to be the case for the spinel group minerals in

hornblendites, as they form anhedral inclusions in olivine and chlorite.

Compositions of the spinel group minerals can easily re-equilibrate during

prolonged cooling, resulting in almost pure magnetite with trace amounts of Ti,

Mg, Al and Cr. Most of the elements contained in the spinel would be lost to

surrounding silicates (Frost and Lindsley 1991).

It can be summarized that both, late stage igneous mineral melt and

solidus reactions involving late stage melt contributed to formation of hornblende

and phlogopite. The former is partly supported by a resorbed nature of olivine

and plagioclase grains. The latter is supported by the presence of clinopyroxene

replacement by both, green or brown hornblende. Although the bulk of the

hornblende and phlogopoite resulted from interstitial melts, some may have

formed during alkali metasomatism.

71

6.1.2 Megacrystic hornblendite

In megacrystic hornblendites, the presence of hornblende megacrysts and

groundmass hornblende can indicate at least two major stages of crystallization.

Megacrysts with their inclusions would represent the first major crystallization

stage, and their mineral paragenesis would be analogous to the crystallization

steps one to four interpreted for the olivine hornblendites. After the emplacement

of the crystal mush containing poikilitic orthopyroxene and clinopyroxene (up to

20% of crystals in “hornblenditic” magma), the intrusion would lose heat to its

surroundings and interstitial melt would crystallize (the second major

crystallization stage), forming the equigranular groundmass consisting

dominantly of clinopyroxene (later this would be almost completely replaced by

hornblende with minor biotite).

Textures involving megacrysts and groundmass are likely to result also

from magma mixing and mingling processes, where a basaltic magma could

entrain chunks with early formed crystals of another basaltic magma. No

disequilibrium textures would form from magmas of similar composition.

Figure 31. Schematic expression of mineral paragenesis in olivine hornblendites. Primary and secondary phases are listed in relative crystallization order. The length of the black bars indicates relative abundance and crystallization order from left to right.

72

Differential entrainment may explain a variance of megacryst abundance in the

hornblendites.

6.1.3 Hornblendite

Equigranular medium- to fine-grained hornblendites can represent one

stage crystallization after emplacement of basaltic melts. Their medium- to fine-

grained nature is affected by their volume, and capability to retain heat within the

host intrusion after emplacement. It is possible that medium-grained varieties

were emplaced in stages when the host intrusions were hot, and high

temperatures could be maintained easily. This would allow sufficient time to grow

crystals of clinopyroxene (later replaced by hornblende). Fine-grained varieties

may represent later intrusions being emplaced into a cooler host.

6.2 Hornblende gabbros

6.2.1 Hornblende gabbro

1/ Plagioclase and clinopyroxene-Plagioclase and clinopyroxene are

interpreted to have formed simultaneously (Fig. 32) resulting in the formation of a

subophitic texture, which is dominant in the hornblende gabbros. The sizes of

plagioclase crystals can be grouped in three major categories (inclusions,

groundmass and phenocrysts), but in reality there is a continuity between the

sizes. Poikilitic hornblende grades into interstitial hornblende that fills spaces

between groundmass plagioclase, often creating an impression that the

groundmass plagioclase is actually an inclusion displaying “subophitic texture”.

73

Experimental studies (McBirney and Noyes 1979) provide an explanation

of the subophitic texture of the plagioclase enclosed by clinopyroxene, and an

increase in plagioclase grain size toward the rim of enclosing clinopyroxene. This

texture is as attributed to simultaneous growth of plagioclase and clinopyroxene.

Hornblende gabbros from the CRIC have similar textures and may be the result

of similar crystallizing conditions. Due to a lower nucleation rate for

clinopyroxene and a faster rate for plagioclase during simultaneous

crystallization, a subophitic texture would be produced. Therefore, clinopyroxene

will grow poikilitically, placing a limit on the growth of plagioclase crystals.

Conversely, plagioclase crystals continue to grow freely and form larger crystals

close to, and away from, the clinopyroxene oikocrysts, locking clinopyroxene in

their interstices. It is likely that the hornblende gabbros formed under similar

conditions and clinopyroxene was later replaced by hornblende.

Figure 32. Schematic expression of mineral paragenesis in hornblende gabbros. Primary and secondary phases are listed in relative crystallization order. Black bars indicate relative abundance and crystallization order from left to right.

74

6.2.2 Plagioclase hornblende gabbro porphyry

Plagioclase hornblende gabbro porphyry contains variable amounts of

plagioclase pheno-/xenocrysts and hornblende megacrysts, which are randomly

distributed throughout the intrusion. In such varieties, some plagioclase forms

first as porphyritic texture and/or becomes entrained as telluric crystals from

another magma. The magma then follows a crystallization trend analogous to

step one in the hornblende gabbros.

6.2.3 Quartz hornblende gabbro

Quartz hornblende gabbro contains hornblende megacrysts, and quartz

that occurs as an interstitial phase within a groundmass of plagioclase-

hornblende, and in the cores of zoned plagioclase where it forms graphic

intergrowths. Within a single quartz-bearing hornblende gabbro sheet, relicts of

olivine, fresh orthopyroxene, hornblende, plagioclase and quartz occur. Such an

association can be a product of magma mixing or mingling.

1/ Plagioclase from basaltic magma intermingled with plagioclase-

quartz clots from tonalite-When plagioclase from tonalitic magma becomes

incorporated into the basaltic magma („„hornblende gabbro” magma), it can

undergo partial resorption of pre-existing andesine rims and new growth of calcic

to highly calcic plagioclase, producing a reversal of zoning. The heat from the

“hornblende gabbro” magma can cause partial melting of cores in tonalitic

plagioclase phenocrysts during the ascent. Other evidence of magma mixing/

mingling is resorbed labradorite/ bytownite cores of telluric plagioclase in

hornblende gabbro. Such resorption and brecciation of telluric plagioclase with

75

labradorite/ bytownite compositions can occur due to a sudden decrease of Ca

activity and higher water content in tonalitic magma that interacts with intruding

“hornblende gabbro” magma. This is analogous to the processes interpreted for

the Sazava intrusions from Bohemia, central Europe (Janousek et al. 2004).

2/ Clinopyroxene as an interstitial phase-Some clinopyroxene occurs

as an interstitial phase contemporaneous with the plagioclase. This results in the

formation of equigranular plagioclase-hornblende groundmass, in which

hornblende replaces clinopyroxene late in the crystallization history.

3/ Megacrystic hornblende-Megacrystic hornblende becomes

incorporated later as a result of mingling of “hornblendite” and host “hornblende

gabbro plus tonalite” (from step one in quartz hornblende gabbro) magmas.

During this process telluric, poikilitic clinopyroxene phenocrysts from

“hornblendite” magma become incorporated into the host “hornblende gabbro”.

4/ Graphic intergrowths-The hotter “hornblenditic” intrusions could be

responsible for partial melting of hornblende gabbros (previously mingled with

tonalite-from step one in quartz hornblende gabbro) and their recrystallization.

Products of the recrystallization would include plagioclase phenocrysts with

graphic intergrowths consisting of hornblende-plagioclase and quartz-plagioclase

pairs and polygonal hornblende.

76

6.3 Hornblende diorites

6.3.1 Hornblende diorite

1/ Plagioclase phenocrysts-Where present, plagioclase phenocrysts are

interpreted to have crystallized prior the emplacement of basaltic/andesitic

magma. As plagioclase phenocrysts have similar compositions as the

groundmass plagioclase, it is likely that these phenocrysts are telluric.

2/ Simultaneous crystallization of plagioclase and hornblende-

Plagioclase and hornblende are interpreted to have crystallized simultaneously

as indicated by their similar size and idiomorphic shape. The observed presence

of quartz can also be an indication of simultaneous crystallization of plagioclase

and hornblende (Janousek et al 2004). Hornblende contains chloritized and

biotitized cores, which suggest the cores were originally pyroxene, and that

hornblende rims crystallized around the pyroxene cores as the melt became

enriched in water. Later, metasomatism replaced the pyroxene cores with chlorite

and biotite.

3/ Alkali feldspar and quartz-Alkali feldspar and quartz are interpreted to

have crystallized last, this is indicated by their interstitial nature. It is likely that

alkali feldspar crystallized prior to, and simultaneously with quartz. However,

graphic intergrowths of quartz and alkali feldspar are absent.

77

6.3.2 Spotted hornblende diorite

The spotted hornblende diorite variety has a more complex crystallization

history. The spotted texture is distinctive and unusual. It requires special

conditions to develop, and is therefore discussed in more detail.

1/ Simultaneous crystallization of plagioclase and clinopyroxene-

Plagioclase is thought to have crystallized simultaneously with clinopyroxene.

The crystallization process could have been similar to the hornblende gabbros

after emplacement of basaltic magma into a partially molten host tonalite.

Subophitic texture would develop as plagioclase crystallized simultaneously with

clinopyroxene. Subsequently, clinopyroxene would be replaced by deuteric/

metasomatic hornblende.

2/ Spotted hornblende-Spotted hornblende formed as the remobilized,

flowing, partly melted tonalite mingled with partly crystallized “hornblende

gabbro”/ ”hornblendite” magma and dismembered clinopyroxene oikocrysts into

clusters, that were later altered to hornblende yielding the spotted appearance.

The spotted texture in the CRIC is thought to be the result of mingling between

the hornblende gabbro/ hornblendite and tonalite because it typically occurs

along the contact between these intrusive phases, and the alignment of the

hornblende spots suggests magmatic flow along the contact. Additional effects of

mingling include a tonalite contribution to the prevalent andesine plagioclase

composition leading to a decreased abundance of mafic minerals in the spotted

hornblende gabbro. Likewise, hornblende gabbro/ hornblendite can also locally

78

affect tonalitic plagioclase, which can develop enriched calcic zones producing a

reverse zoning in plagioclase grains.

In the LCIC, the heterogeneously spotted hornblende gabbros/ hornblende

diorites include large volume intrusions. The most likely scenario to account for

the observed textures is that basaltic magma was injected at higher pressure into

crystal-poor tonalitic melt. This basaltic magma would thoroughly disperse and

mingle with flowing tonalitic magma (referred to as a “thorough” mingling in the

section 3.2.5) The initial temperature gradient between dispersed basaltic

magma droplets (possibly carrying the seeds of clinopyroxene and plagioclase

crystals) at the contact with tonalitic magma would affect nucleation rates (slower

for clinopyroxene, faster for plagioclase), and in combination with induced flow,

would result in an abundance of spotted texture. Such “thorough” magma

mingling (mixing) could take place in deeper levels where magmas of different

compositions were at higher temperatures. After mingling they would remobilize

and become emplaced into mid-crustal levels. Patches of acicular hornblende

texture, commonly occurring within spotted hornblende texture were likely

produced by smaller volume basaltic pulses that intruded partly crystallized

mingled magmas and chilled against them.

A spotted gabbro texture has been identified in the Jurassic gabbroic

intrusions in Antarctica (Vuori and Luttinen 2003). They are part of a 300-500m

wide layered gabbro zone that consists of alternating metre-scale dark olivine

gabbroic bands that grade into grayish gabbroic rock of a spotted appearance.

This texture was also found in 60 m wide medium- to coarse-grained dykes

79

cutting across the basaltic country rock. Spots can be large, ~ 1 cm in diameter

and a spotted appearance is interpreted as a glomerophyric texture displayed by

clusters of olivine and pyroxene. The whole zone of layered gabbros is believed

to be the uppermost part of an intrusion due to the presence of pegmatoidal

batches.

6.3.3 Acicular hornblende diorite

The acicular crystal habit is an indicator of a strong degree of

undercooling due to a steep temperature gradient between two mingling magmas

(Blundy and Sparks 1992). Presence of tonalitic plagioclase xenocrysts with

reverse zoning in acicular hornblende diorite also suggests the mingling of two

magmas. During this process a calcic rim would develop on tonalitic plagioclase

from a Ca supply from basaltic magma.

1/ Apatite-Apatite crystallized first as abundant needles that formed at

numerous nucleation sites due to a steep temperature gradient (Fig. 33).

2/ Hornblende and plagioclase-Hornblende and plagioclase precipitated

next. Hornblende also nucleated at numerous sites and grew needle-like crystals

due to a steep temperature gradient. Plagioclase formed subhedral crystals with

apatite inclusions.

3/ Quartz, biotite, and magnetite-Quartz, biotite, and magnetite were the

last to crystallize. Their shapes vary from hypidiomorphic to allotriomorphic. All

phases form an interlocking mosaic.

80

4/Xenocrysts of quartz, and clots of biotite and quartz-Xenocrysts are

present, and are interpreted to have come from the host tonalite. Also common is

a development of a disequilibrium reaction rim consisting of hornblende or

plagioclase crystals that mantle tonalitic quartz or plagioclase xenocrysts.

Analogous disequilibrium textures are described elsewhere (Blundy and Sparks

1992; Hibbard 1995; Janousek et al. 2004; Wiebe 1968, 1973, 1974, 1980, 1987,

1988, 1993, 1994; Wiebe et al. 2002, 1997). Most notably, the Sazava intrusions

(Janousek et al. 2004; Vernon 1991) contain quartz occelli-xenocrysts in basic

bodies, introduced from felsic magmas. Quartz would get resorbed in basic melts

and become a substrate for heterogeneous nucleation of hornblende and

pyroxene that would form “coronas”. They inferred that the quartz grains extract

latent heat from the adjacent mafic magma and their undercooled surface

becomes a location for preferential nucleation of mafic minerals such as

hornblende and pyroxene. Plagioclase is found to be mantled by more sodic

plagioclase “coronas”. Such textures are classic examples of magma mixing

(Janousek et al. 2004).

Figure 33. Schematic expression of mineral paragenesis in hornblende diorites. Primary and secondary phases are listed in relative crystallization order. Black bars indicate relative abundance and crystallization order from left to right.

81

6.4 Tonalites

6.4.1 Tonalite

1/ Biotite-Biotite is interpreted to have formed first (Fig. 34). It is an

idiomorphic, minor ferromagnesian phase, and the presence of rare relicts of

ferromagnesian minerals within biotite suggests mixing of tonalite magma with a

more mafic magma.

2/ Plagioclase-Plagioclase is interpreted to have crystallized next; it is

one of the dominant phases, and is zoned. Some of the crystals show resorption

of individual zones, which indicates a complex crystallization history.

3/Quartz-Quartz is interstitial phase between plagioclase and biotite

grains and crystallized last.

6.4.2 Trondhjemite

1/Plagioclase-Some plagioclase grains are interpreted to have formed

prior to and some simultaneously with quartz. Those formed first are larger,

Figure 34. Schematic expression of mineral paragenesis in tonalites. Primary and secondary phases are listed in relative crystallization order. Black bars indicate relative abundance and crystallization order from left to right.

82

idiomorphic and display normal zoning. Albite and oligoclase compositions are

believed to be a subsolidus replacement of andesine by more sodic plagioclase.

2/Vermicular quartz-plagioclase intergrowths-Vermicular intergrowths

are common and are a very distinctive texture of this rock; such texture implies

simultaneous crystallization of quartz and plagioclase.

83

7: WHOLE ROCK GEOCHEMISTRY

Twenty seven major and trace element analyses on rocks from the CRIC

and LCIC are presented in Appendix 4. The geochemical compositions of CRIC

and LCIC range from picrite-basalt of hornblendites through basalts/ basaltic

andesite/ andesite of hornblende gabbros and hornblende diorites to dacite/

rhyolite compositions of tonalites (Fig. 35). The Leagh Creek stocks of

hornblende gabbro and hornblende diorite, as well as hornblende dioritic chilled

mafic enclaves from both CRIC and LCIC display alkalic affinities, plotting as

tephrite basanite/ trachybasalts (Fig. 35). Samples of Karmutsen country rock

have picro-basalt composition with alkalic affinity (Fig. 35).

CRIC has dominantly a calc-alkaline signature, with chilled mafic enclaves

of hornblende diorite plotting in the tholeiitic field on SiO2 vs FeO*/MgO and AFM

diagrams (Fig. 36A and B). LCIC hornblende gabbro/diorite stocks and chilled

mafic enclaves show dominantly tholeiitic signature, which is also characteristic

of Karmutsen country rock (Fig. 36A and B). Calc-alkaline and tholeiitic magmas

of both intrusive complexes are typical and common in island arcs (Miyashiro

1974).

84

Picro-basalt

Andesite

RhyoliteTrachydacite

Trachyte

Phonolite

40 45 50

SiO wt%2

Na

O

+K

O

wt%

22

55 60 65 70 750

2

4

6

8

10

12

14

16

Tephri-phonolite

(Foid monzosyenite)

PT (Foid monzodiorite)

TephriteBasanite

(Foid gabbro)

Trachy-andesite

(Monzodiorite)

(Syenite)

(Foid syenite)

(Monzo- diorite)

BTA

Foidite(Foidolite)

Basalt

TB (MG)

(Gabbro)

(Ultramaficplutonic rock)

(Diorite)

(Diorite)

(Tonalite/ Granodiorite)

(Tonalite/ Granite)

Basalticandesite

Dacite

40

Fe

O*/

MgO

0

5

10

15

50 60 70 80

SiO2

Tholeiitic

Calc-alkaline

A

Thole iitic

Na O+K O2 2 MgO

FeO*

Ca lc-alka line

B

On a K2O-TiO2-P2O5 tectonic discriminant diagram (Pearce et al., 1975) all

samples plot in a continental setting, which is inconsistent with a simple island

arc affinity, but consistent with arc magmatism on a mature microcontinent, e.g,

Figure 35. TAS diagram shows distribution of samples from the CRIC and LCIC. Black solid line divides alkaline from subalkaline field for the majority of intrusions (after Irvine and Baragar 1971; LeBas et al. 1986; LeMaitre 2002; plutonic equivalents from Streckeisen 1976). Oxides were normalized to 100% on volatile free basis. Abbrevations: TB=trachybasalt; MG=monzogabbro; BTA=basaltic trachyandesite; PT=phonotephrite

Conuma River hornblendite-sheets and stocks

Conuma River hornblende gabbro sheets and stocks and hornblende diorite stocks

Conuma River tonalite, hybridized diorite and trondhjemite-host intrusion and stocks

Conuma River hornblende diorite-chilled mafic enclaves

Leagh Creek hornblende diorite-chilled mafic enclavesLeagh Creek hornblende gabbro/hornblende diorite-stocks

Karmutsen Formation-country rock septa

Leagh Creek tonalite and trondhjemite-stocks

Legend

Figure 36. Calc-alkaline vs tholeiitic trend for the CRIC and LCIC. A: FeO*/MgO vs SiO2 diagram shows majority of CRIC intrusions in calc-alkaline field. Chilled mafic enclaves of both complexes and hornblende gabbro/ diorite stocks of LCIC, together with Karmutsen country rock plot in the tholeiitic field (after Miyashiro 1974). B: AFM diagram exhibits calc-alkaline trend for majority of CRIC intrusions. Oxides were

normalized to 100% on volatile free basis. Symbols as in figure 35.

85

Wrangellia (Murphy 2007) (Fig. 37A). In the Nb vs La discrimination diagram, all

samples fall within the orogenic andesite field, mostly in the low-K subfield, which

is again in agreement with a volcanic arc setting (Fig. 37B; Appendix 4: Fig. A4-

3).

K2O

TiO2

Oceanic

ContinentalContinental

Oceanic

A

P2O5

30

20

10

2 4 6 8 10Nb (ppm)

La

(pp

m)

High-K

Med

ium

-K

Low-K

La / N

b = 5

La / Nb = 1

La / Nb =

2 = Bulk E

arth

Orogenic Andesite

N-M

ORB

E-MORB

B








Legend

Mullen‟s (1983) MnO-TiO2-P2O5 plot (Fig. 38A) shows that the majority of

samples have a calc-alkaline signature. Hornblende dioritic chilled mafic

enclaves of both complexes fall into an arc tholeiite field (Fig. 38A). Karmutsen

country rock samples plot in the MORB field indicating an oceanic tectonic

setting. A similar geochemical signature is displayed in a Th-Hf/3-Ta diagram

(Fig. 38B), in which the a majority of the samples shows arc calc-alkaline affinity,

Figure 37. A: K2O-TiO2-P2O5 discriminant diagram indicates continental tectonic affinity of the CRIC and LCIC. Karmutsen country rock plots in the oceanic tectonic setting (after Pearce et al. 1975). B: Nb vs La discriminant diagram shows orogenic andesite (island arc) tectonic affinity of samples (after Gill 1981). Oxides were normalized to 100% on volatile free basis.

86

with LCIC chilled mafic enclave and LCIC hornblende gabbro/diorite stocks

plotting close to the arc-tholeiites and Karmutsen country rock septa in the

vicinity of N-MORB field (Fig. 38B). Additional triangular discriminants with similar

results are in Appendix 4: Fig. A4-4.

MnO*10 P2O

OIB-thol

ARC-thol

M ORB

OIB-alk

ARC-calc-alk

TiO2

A

5

Th Ta

Hf/3

E-M ORB

& W PTB

N-M ORB

W PAB

ARC-thol

ARC-CalcA lk

B








Legend

Calc-alkaline signature of CRIC hornblenditic and hornblende gabbroic

sheets and stocks, and tholeiitic behavior of chilled mafic enclaves from both

complexes, and LCIC hornblende gabbroic/ dioritic stocks are likely due to

relatively contemporaneous arc calc-alkaline and tholeiitic magma sources

undergoing their own evolution and expelling magma pulses into a common

Figure 38. A: MnOx10-TiO2-P2O5x10 plot indicates calc-alkaline signature for the majority of samples in arc setting, with hornblende dioritic chilled mafic enclaves in the arc-tholeiite field and Karmutsen country rock septa in the MORB field (after Mullen 1983). B: Th-Hf/3-Ta plot shows majority of intrusions in arc-calk-alkaline field (after Wood 1980). Hf-Th-Ta elements are useful in showing how subduction component controls trace element signature. CRIC and LCIC data plots in subduction enrichment zone and crust magma interaction zone. WPABG= within plate alkaline basalts, WPTB= within plate tholeiitic basalts, OIB=ocean island basalts, E-MORB=enriched mid-ocean ridge basalts, N-MORB=normal mid-ocean ridge basalts. Oxides were normalized to 100% on volatile free basis.

87

magmatic locus. Tholeiitic behaviour of Karmutsen country rock and its oceanic

affinity confirms the typical geochemical signature of the Karmutsen Formation

on the Wrangellia terrane (Yorath et al. 1999).

Analyses of sheets and stocks of CRIC hornblendites, on a volatile free

basis, show SiO2 contents from 41.7-48.1 wt%. The hornblendites have high

content of MgO (19.1-29 wt%), FeO* (9.8-13.3 wt%), where Fe*O is calculated

as FeO+0.8998Fe2O3. They contain 7.3-13.7 wt% Al2O3 and 3.8-7.4 wt% CaO.

The hornblendites (Appendix 4: Fig. A4-5) are low in Na2O (0.9-1.5 wt%), K2O

(0.3-1.1 wt%), TiO2 (0.24-0.47 wt%), MnO (0.19-0.24 wt%) and P2O5 (0.08-0.16

wt%).

Sheets, stocks and chilled mafic enclaves of hornblende gabbros and

hornblende diorites of both complexes, calculated on a volatile free basis, have

SiO2 contents from 44.8-60.1 wt%. These samples have high contents of Al2O3

(9.7-19.9 wt%), MgO (4-14 wt%), CaO (6.6 -12.9 wt%) and moderate contents of

FeO* (4.8-17.5 wt%), where Fe*O is calculated as FeO+0.8998Fe2O3. These

samples are low in Na2O (1.4-4.2 wt%), K2O (0.5-1.5 wt%), TiO2 (0.4-1.3 wt%),

MnO (0.1-0.2 wt%) and P2O5 (0.06-0.5 wt%).

Stocks of tonalite (calculated on volatile-free basis; including trondhjemites

and hybridized diorite) have SiO2 from 67.8-76.6 wt%. Tonalites have high

content of Al2O3 (12.3-16.1 wt%), and moderate content of Na2O (3.7-4.8 wt%)

and CaO (1.1-4.3 wt%). They are low in K2O (0.4-3.4 wt%), FeO* (1.5-6.1 wt%),

MgO (0.3-1.2 wt%), TiO2 (0.15-0.5 wt%), MnO (0.02-0.07 wt%) and P2O5 (0.04-

0.2 wt%). FeO* was calculated as FeO+0.8998Fe2O3.

88

Harker diagrams (Fig. 39) indicate that composition of intrusions form a

linear array with negative slope for CaO, TiO2, FeO*, MnO, P2O5, MgO, V, Cu,

Co, Cr, Ni, Y, Yb and Sc. Positive slopes reflect an increase in abundance of

K2O, Na2O,La, U, Zr, Ce, Th, Nd , Ho and Hf with SiO2 increase. Al2O3, Ba, Rb,

Cs, Nb, Ta, Sm, Eu, Dy, Er, Tm, Tb, Gd and Lu appear to increase in the interval

from ultramafic to intermediate composition and decrease with further SiO2

evolution. Hornblendites always plot away from the linear array.

0.1

1

10

100

40 50 60 70 80

CaO

TiO2

SiO2wt%

0.01

0.1

1

10

40 50 60 70 80

MnO

Al2O3

FeO*

SiO2 wt%0.01

0.1

1

10

40 50 60 70 80

P2O5

Na2O

SiO2 wt%

Figure 39. Harker diagrams with major and minor oxides and trace elements with respect to an increase of SiO2 in CRIC and LCIC. Major and minor oxides normalized to 100% on volatile free basis.







Legend

89

0.1

1

10

100

40 50 60 70 80

K2O

MgO

SiO2 wt%0.1

1

10

100

1000

40 50 60 70 80

Sr

La

Ta

Cu

SiO2 wt%

0.1

1

10

100

1000

40 50 60 70 80

Ba

Cs

Rb

SiO2 wt%0.1

1

10

100

1000

40 50 60 70 80

V

Nd

Nb

U

SiO2 wt%

0.1

1

10

100

1000

40 50 60 70 80

Ce

Th

Zr

SiO2wt%0.1

1

10

100

40 50 60 70 80

Sm

Y

Eu

SiO2 wt%

Figure 39 (Continued).

90

0.1

1

10

100

1000

40 50 60 70 80

SiO2 wt%

Cr

Dy

Er

Tm

0.1

1

10

100

1000

40 50 60 70 80

Hf

Tb

Co

SiO2 wt%

0.1

1

10

100

40 50 60 70 80

Ho

Gd

Sc

SiO2wt%0.1

1

10

100

1000

40 50 60 70 80

Yb

Lu

Ni

SiO2 wt%

Normative mineralogy of all intrusions was calculated using Fe3+/Fe2+ of

0.3 (Fig. 40). Hornblendites are dominantly olivine normative, and mafic and

intermediate intrusions are dominantly quartz normative. Common normative

minerals include orthoclase, albite, anorthite, diopside, hypersthene, magnetite,

apatite and ilmenite. Rare normative minerals are nepheline and corundum.

Figure 39. (Concluded).

91

0

5

10

15

20

25

30

35

40

45

50

OR AB AN DI WO HY OL Q NE AP IL C MT

Hornblendites

Hornblende gabbros and

hornblende diorites

Tonalites

No

rma

tive

min

era

ls(m

ol %

)

Representative normative mineralogy for intrusions

from Conuma River and Leagh Creek localities

Trace elements of the CRIC, normalized to N-MORB, overall have slightly

negative slopes defined by enrichment in incompatible elements and flattening in

the HFSE and HREE region (Fig. 41A). This pattern is characteristic of arc

magmas (Murphy 2007). The LILE enrichments exhibit a slight positive anomaly

in Ba and K and slightly negative Th anomaly. Nb and Ta show a slight negative

anomaly, which is another example of an arc magma signature. Positive

anomalies in Pb and Sr are distinctive, but not a reliable indicator of an arc

magma signature, as these elements can easy migrate in and out of the system.

Zinc, Mn, Co, Cr and Ni show positive anomalies for most of the intrusions.

Scandium and Cu show negative anomalies for most of the intrusions. The

overall pattern lacks Zr and Eu anomaly.

Figure 40. Normative mineralogy of CRIC and LCIC. The most abundant normative mineral in hornblendite is olivine; anorthite and diopside are abundant in hornblende diorite and hornblende gabbros and quartz and albite are most abundant in tonalites.

92

CRIC hornblendites show a consistent trace element pattern suggestive of

their genetic linkage (Fig. 41B). The pattern is characterized by Ni and Cr

enrichments. As these elements are incorporated preferentially into olivine and

pyroxene, their enrichment in hornblendites may be rationalized as cumulus

minerals. A low REE (lanthanides) pattern reflects the presence of olivine,

clinopyroxene and orthopyroxene. REE‟s are incompatible and prefer to stay in

the melt during the early fractionation history. Hornblendites show slight positive

Eu anomaly in REE plot.

The trace elements of CRIC hornblende gabbros and hornblende diorites

show some variations in the overall pattern (Fig. 41C). The variations can be

indicative of different arc magma sources and/or more complex arc magma

paragenesis with respect to hornblendites. Some sheets and stocks of

hornblende gabbros/ diorites show enrichment in Cr and Sc in contrast with other

hornblende gabbro/ diorite stocks and chilled mafic enclaves. A slight positive Eu

anomaly is characterized for all hornblende gabbros/ diorites and can be

attributed to the abundant plagioclase. A slight enrichment of Rb in hornblende

gabbros/ diorites, in contrast with hornblendites can be indicative of the

abundance of plagioclase as this element tends to be incorporated into

plagioclase.

CRIC tonalites follow the overall arc magma pattern, but display variations

within this pattern with respect to all intermediate, mafic and ultramafic intrusions

(Fig. 41A). It is difficult to comment on their trace element signature in greater

detail due to incomplete trace element analysis. A complete analysis of a

93

trondhjemite stock exhibits a pattern that suggests no genetic link to the rest of

the CRIC.

The CRIC and LCIC exhibit similar profiles, which indicate that LCIC

intrusions are also products of island arc magmatism (Fig. 41D). It is worth noting

that the LCIC intrusions plot in the upper part of the overall REE pattern

characterized by intermediate compositions, whereas the CRIC mafic and

ultramafic intrusions plot in the lower part of the pattern. Based on field

observations, the intermediate compositions of LCIC intrusions are likely a result

of basaltic and silicic magma mingling processes.

94

Figure 41. Trace elements and REE plots. A: All intrusions from CRIC. B: CRIC hornblendites.

95

Figure 41. (Continued). Trace elements and REE plots. C: Hornblende gabbros and hornblende diorites from CRIC. D: All intrusions from CRIC and LCIC.

96

8: AR-AR DATING

Hornblende Ar-Ar dates were obtained from a hornblende-plagioclase

pegmatite in the vicinity of the CRIC layered structure, and from the LCIC

hornblende gabbro. Both samples yield Early to Middle Jurassic ages.

The samples were crushed and sieved at 2 to 0.5 mm. Approximately 50

hornblende grains of 0.250 mm size were handpicked using tweezers and a

microscope. Only fresh, brown-green fragments of hornblende crystals were sent

for analyses to the Pacific Centre for Isotopic and Geochronologic Research at

the University of British Columbia in Vancouver, BC.

Hornblende from the hornblende-plagioclase pegmatite phase of the CRIC

layered intrusion yields an age of 189.9±2.1 Ma calculated from 85.3% of 39Ar

gas fraction released. Hornblende from the LCIC hornblende gabbro yields a

plateau age of 179.7±3 Ma calculated from 92.2% of 39Ar gas fraction. These

dates are assumed to represent the 500oC Ar-closure temperature of hornblende

and are approximate ages of crystallization.

The CRIC appears to be a few millions years older than the LCIC. Both

ages confirm that complexes formed during Early to Middle Jurassic and the

nature of the contacts between the intrusions suggest they are contemporaneous

(Figs. 42, 43; Appendix 5: Fig. A5-1; Tables A5-1, 2).

97

Figure 42. Plateau age of 189.9±2.1 Ma of hornblende from the CRIC hornblende-plagioclase pegmatite (sample DM05-212A). White rectangles (include error calculations) represent rejected ages, resulting from initial heating and Ar release from marginal zones of the crystal. Dark rectangles form a representative plateau age comprised of three heating steps. J= Flux correction factor; MSWD=Mean Squared Weighted Deviates.

Figure 43. Plateau age of 179.7±3 Ma of hornblende from the LCIC hornblende gabbro (sample DM06-38). White rectangles (include error calculations) represent rejected ages, resulting from initial heating and Ar release from marginal zones of the crystal. Dark rectangles form a representative plateau age comprised of six heating steps. J= Flux correction factor; MSWD=Mean Squared Weighted Deviates.

98

9: THERMOBAROMETRY

The CRIC consists of contemporaneous hornblenditic, gabbroic, dioritic,

tonalitic and trondhjemitic intrusions. It represents multiple episodes of igneous

activity characterized by numerous injections of various magma volume,

compositions and emplacement times, into a solidifying intrusive environment.

Temperatures of intrusions prior to, and during, emplacement vary, as well as

crystallization temperatures. Field relations exhibit abrupt and gradiational

contacts between individual intrusions, sometimes textures suggest a slight initial

chill, indicating high ambient temperatures, and fast thermal re-equilibriation

between new intrusive pulses and the host intrusion, followed by simultaneous

slow cooling during and after the major magmatic period.

9.1 Olivine-orthopyroxene thermometer

Olivine hornblendites from the CRIC contain some fresh grains of olivine

and orthopyroxene. Although, some olivine grains appear to be deeply embayed

by orthopyroxene, the majority of grains suggest the coexistence and textural

equilibrium of these two phases. Microprobe data was obtained from olivine and

orthopyroxene cores and rims (Appendix 3: Table A3-1, 2).

A number of studies present thermodynamic models for Fe-Mg mixing for

Fe-rich olivine-orthopyroxene pairs (Koch-Muller et al. 1992; Ramberg 1951;

Sack 1980; Sack and Ghiorso 1989). Sack (1980) presented thermodynamic

99

data for Fe-Mg in grains of olivine and orthopyroxene, and modeled Fe2+-Mg2+

distribution between olivine and orthopyroxene, via the reaction:

½ Mg2Si2O6 + ½ Fe2SiO4 = ½ Fe2Si2O6 + ½ Mg2SiO4. (1)

which appears to be a potentially useful geothermometer. The olivine

compositional limits for Sack (1980) dictate the olivine should have an X Fe of

more than 0.6 or less than 0.2. The olivine crystals in olivine hornblendite sheets

from the CRIC are Mg-rich and their XFe is approximately 0.2.

The exchange reaction can be defined by the apparent equilibrium

constant KD OL-OPX at 700oC and the relationship can be express by the equation:

KD OL-OPX = (XMgOPX) x (XFe

OL) / (XFeOPX) x (XMg

OL) (2).

The KD OL-OPX for Fe-Mg exchange between olivine-orthopyroxene in

olivine hornblendite from the CRIC was calculated at 1.1 and 1.18.

At higher temperatures, the slight positive deviations from ideal mixing

exist in orthopyroxene, as well as the variations in composition dependence of

the equilibrium constant. Though overall, as pointed out be Sack (1980), the

positive deviations from ideal mixing do not strongly affect compositional and

temperature dependencies. A decrease in the compositional dependence of KD

OL-OPX is correlated with an increase in temperature above 1000oC. Figure 44

shows the relationship between KD OL-OPX and XFe in olivine over the temperature

range 500oC-1200oC at 1 atm. This plot is in accordance (with some restrictions)

with high pressure olivine-orthopyroxene data from other workers. Estimated

100

equilibrium temperatures between olivine and orthopyroxene in olivine

hornblendites from the CRIC are 850o± 20oC.

9.2 Al2O3 and TiO2 in hornblende thermobarometry

Olivine hornblendites and hornblende gabbros contain abundant

hornblende. Petrographical analyses of textures indicate partial to complete

replacement of pyroxene by hornblende. The mineral paragenesis in both rock

types suggests that some of the hornblende has a magmatic origin. The

composition of a magmatic hornblende can be used to estimate temperature and

pressure during the crystal/rock formation (if other criteria are met). In the case of

mafic intrusions from the CRIC, it is impossible to determine if the hornblende is

a primary or secondary phase, especially if complete replacement of pyroxene by

hornblende has occurred. Another problem represents a choice of

Figure 44. A schematic plot of the apparent equilibrium constant (KD

OL-OPX)

for Fe-Mg exchange in olivine –orthopyroxene pairs and mole fraction of Fe in olivine (XFe

OL), over the temperature

range from 500o-1200

oC at 1 atm (after

Sack 1980). The blue square indicates the equilibrium temperature of 850

o±

20oC for olivine-orthopyroxene pairs

from the CRIC olivine hornblendites (samples DM05-212A and KF07-JN1).

101

thermobarometer. There are convenient thermometers and barometers

established from temperature and pressure sensitive coupled substitutions

involving Al in hornblende, and from temperature sensitive ion exchange

amphibole-plagioclase equilibria (Auge 1997; Bachmann and Dungan 2002;

Holland and Blundy 1994; Schmidt 1992; Stone 2000). Such thermobarometers

are applicable to rock types with specific buffering mineral assemblages that are

different from olivine hornblendites and hornblende gabbros from the CRIC. In

spite of a number of problems associated with these rock types, compositions of

brown and green hornblendes were used for pressure and temperature

estimates, and discrepancies in the temperatures and pressures obtained.

Ernst and Liu (1998) introduced a semi-quantitative thermobarometer that

uses a petrogenetic grid consisting of isopleths of Al2O3 and TiO2. The grid is

based on experimental studies on temperature and pressure dependence of

Al2O3 and TiO2 content in calcic amphiboles. The experiments used synthesized

calcic amphiboles from mid-ocean ridge basalt and were run in a temperature

range of 650o-950oC, and pressure range of 0.8-2.2 GPa (8-22 kbar), under

water saturated conditions and with fO2 controlled by the quartz-fayalite-

magnetite (QFM) buffer. The shape and slope of Al2O3 and TiO2 isopleths

indicates that Al2O3 content increases with both pressure and temperature, and

that TiO2 content is pressure insensitive and proportional to temperature (Ernst

2002; Ernst and Liu 1998).

Applying the Ernst and Liu (1998) Al2O3 and TiO2 thermobarometer, the

green hornblendes from both the olivine hornblendites and hornblende gabbros

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yield extremely high pressure estimates of approximately 18-19 kbar at

temperatures of 570o± 20oC (Fig. 45). Brown hornblendes from both,

hornblendites and hornblende gabbros yield pressure estimates 3-4 kbar at

860o± 20oC (Fig. 45).

9.3 AlVI in hornblende barometer

Larocque (2008) studied amphiboles from olivine hornblendites occurring

in the Port Renfrew region of Vancouver Island. As previously mentioned, these

hornblendites texturally and chemically resemble the hornblenditic sheeted

intrusions from the Conuma River locality. Larocque (2008) identified and

described hornblende and phlogopite from the Port Renfrew hornblendites as

having a magmatic origin. He applied an empirical barometer, which he derived

from published mineral chemistry for amphiboles from experiments on high MgO

basalts in combination with the work of Adam et al. (2007) on AlVI in basaltic

hornblendes. Larocque (2008) found that AlVI concentration increases with an

increase in pressure due to a shift of Al from the tetrahedral to octahedral site.

Figure 45. A petrogenetic grid with Al2O3 and TiO2

isopleths, showing the temperature and pressure dependence of Al2O3 and

TiO2 in hornblende (after Ernst and Liu 1998). Green and brown hornblendes from the Conuma River locality are plotted as yellow and red squares respectively.

103

Adam et al. (2007) experiments were run to crystallize amphibole in subliquidus

conditions at the range of pressure from 0.5 to 2 GPa (5-20 kbar) and 1000o-

1050oC from hydrous nepheline basanite and olivine basalt as starting

compositions. Compositional variations in amphiboles resulted as a response to

increases in pressure, changes in fO2 and the activity of H2O. These experiments

showed that under certain circumstances, amphibole can be genetically

associated with basalts and can be a fractionating phase from basaltic magmas.

Amphiboles that crystallized during these experiments were mostly pargasites

and minor kaersutites.

In addition, the work of Costa et al. (2004) focused on the evaluation of

sensitivity of AlVI to changes in fO2 and temperature, under water saturated

conditions. After evaluation of these factors using Pinatubo dacite they found that

fO2 and temperature do not strongly affect Al partitioning between tetrahedral

and octahedral sites.

Based on these studies, the Larocque (2008) proposed an empirical

barometer:

AlVI cations = 0.056 x P + 0.008 (3)

This barometer was applied in this study to evaluate pressures at which the

CRIC hornblendites and hornblende gabbros crystallized. Green hornblende from

both hornblendites and hornblende gabbros yields extremely high pressure

estimates of approximately 8.7 kbar. Brown hornblende from both, hornblendites

and hornblende gabbros yield reasonable pressure estimates on the order of 4.3

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kbar similar to the 4.7-8.8 kbar estimates from the Port Renfrew area by

Larocque (2008).

9.4 Summary and interpretation

The olivine and orthopyroxene from olivine hornblendite sheets from the

CRIC equilibrated at the temperature 850o± 20oC (Table 2). This temperature is

reasonable for equilibrating olivine-orthopyroxene pairs at a pressure of 1 atm. In

the case of olivine hornblendites that crystallized at higher pressures than 1 atm,

the experiment‟s pressure appears as a restriction to the application of this

thermometer, although Sack (1980) mentions that some higher temperature and

pressure olivine-orthopyroxene pairs agree with his experiments.

Thermobarometer Sack (1980) thermometer Ernst and Liu (1998) thermobarometer Laroque (2008) barometer

Phases involved olivine-orthopyroxene Al2O3 and TiO2 in hornblende Al VI in hornblende

Experiment's temperature 500o- 1200o

C 650o- 950

oC 1000o- 1050oC

Experiment's pressure 1 atm = 0.001 kbar 8-22 kbar 5-20 kbar

Estimated temperature 850o± 20oC G hornblende: 570o± 20oC n/a

B hornblende: 860o± 20oC

Estimated pressure n/a G hornblende: 18-19 kbar G hornblende: 8.7 kbarB hornblende: 3-4 kbar B hornblende: 4.3 kbar

Table 2. Summarized equilibrium temperatures and pressure estimates for olivine hornblendites and hornblende gabbros from the CRIC. Abbreviations: G=green, B=brown, n/a=not applicable. * Note: For comparison, the estimated pressure range for Port Renfrew olivine hornblendites by Larocque (2008) is 4.4-8.8 kbar .

The estimated equilibrium temperature of the brown hornblende from

alternating sheets of hornblendites and gabbros is 860o± 20oC with a pressure of

3-4 kbar, using Ernst and Liu (1998) thermobarometer. Green hornblende

exhibits a lower equilibration temperature 570o± 20oC and a higher pressure of

18-19 kbar. These estimates are called into question because there are many

restrictions to the application of this thermobarometer with respect to olivine

hornblendites and hornblende gabbros from the CRIC. These restrictions include

105

disequilibrium textures (zoned hornblende), replacement textures (pyroxene

replaced by hornblende), uncertain fO2 conditions, uncertain water content in

melt crystallizing olivine hornblendites, and a high probability of numerous re-

equilibration events during a long, slow cooling process.

Based on the mineral paragenesis (Chapter 5), some of the green

hornblende may be magmatic. This hornblende contains Al concentrations

yielding extremely high pressures (~18 kbar) at very low temperatures (~580oC).

Such estimates appear unrealistic. In contrast, brown hornblende is believed to

have crystallized subsolidus replacing Ti-clinopyroxene, yielding moderate

temperatures (~870oC) at lower pressures (~3.5 kbar). The key component in

temperature estimate is Ti, and it may be a good indicator of an early formed,

higher temperature phase enriched in Ti. As this phase was likely to be

clinopyroxene instead of hornblende, it is not considered appropriate to use the

Ti content to estimate the crystallization temperature estimate for the brown

hornblende.

Lastly, the Larocque (2008) barometer yields a pressure range of 4.3-8.7

kbar for the CRIC olivine hornblendites. Comparing pressure estimates from both

Ernst and Liu (1998) and Larocque (2008) barometers, the green hornblende

consistently yields significantly higher pressures than brown hornblende.

Due to a complex mineral paragenesis, temperature and pressure

estimates for crystallization of hornblende in olivine hornblendites and

hornblende gabbros are problematic and may not be applicable to the rocks in

this study area.

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10: CRYSTALLIZATION MODELING

Crystallization modeling of geochemical data was used to test if

contemporaneous hornblenditic, hornblende gabbroic/ dioritic and tonalitic

plutonic rocks of the CRIC and LCIC can be genetically related, and if a part of

the magma evolution in the Bonanza arc can be reconstructed from these two

localities.

Jurassic Bonanza arc rocks also outcrop in other areas of Vancouver

Island. Published whole rock and trace element geochemistry data of Bonanza

igneous rocks from the Port Renfrew (Larocque 2008) and Port Alberni area -

Broken Islands region (DeBari et al. 1999) were used in crystallization modelling

in order to better understand magma paragenesis within the Bonanza arc setting

by comparing modeling results to the results from the Conuma River locality.

As the Bonanza arc could have been a part of a Jurassic island chain,

whose northern portion would then represent the Talkeetna arc, in south-central

Alaska, published geochemical data from the Talkeetna arc-Tazlina Lake

(Greene et al. 2006) was also used in the crystallization modeling to constrain

the early fractionating history of the Talkeetna magmas. These results are

discussed in connection to the evolution of Bonanza magmas. See figure 1 for

the locations of the published data used in the crystallization modeling.

Programs Stonergram version 3.2 and Fraspide, (Derek Thorkelson,

unpublished), allow for major oxide and trace element crystallization modeling

107

(Appendix 6). The programs are designed to evaluate processes such as

fractional crystallization, mineral accumulation, mixing and assimilation by

comparing a possible “parental” composition with other “evolved” samples from

the same suite. Geochemical data of the evolved samples are normalized to the

parental composition and both, along with a model composition, are graphically

displayed.

10.1 Crystallization modeling results from the Conuma River and Leagh Creek intrusive complexes (Bonanza arc)

A primary mantle-derived magma may be parental to many of the CRIC

and LCIC igneous rocks. For the purpose of modeling, a sample of near-primary

primitive gabbro was selected in order to test hypotheses of fractionation, mixing

and crystal accumulation using the program Stonergram, which evaluates major

oxide abundances. The gabbro is a non-cumulate, plagioclase-phyric, quartz-

hornblende gabbro with a Mg# of 73.4, and would be in equilibrium with olivine of

Fo 90.2 (calculated under assumed Fe3+/Fe2+ ratio of 0.3).

Modeling was successful in relating parental gabbro to all CRIC

hornblendite varieties by the addition of minerals (accumulation). The parental

gabbro can be related to hornblendites by accumulation of mainly olivine with

minor plagioclase, clinopyroxene and magnetite. Proportionally, 0.5 to1.8 parts of

the crystal assemblage added to 1 part of parental gabbro produced a good

match to several of the hornblendite varieties (Appendix 6: Figs. A6-2-3; Table

A6-1). Therefore, the hornblendites are confirmed as cumulates.

108

A genetic link between the CRIC hornblende gabbro sheet and the

parental gabbro was also evaluated with the program Stonergram. The model

requires an accumulation of plagioclase, clinopyroxene and orthopyroxene in

combination with the fractionation of magnetite (Appendix 6: Fig. A6-8A, B). This

is difficult to explain geologically, and such a model requires a necessarily

complex process to produce these rocks. However, another CRIC hornblende

gabbro sheet was modeled by the (complete) mixing of chemical constituents

from two and half parts of hornblende gabbro with 1 part of hornblendite.

Chemical composition of the model produced by this mixing resembled the

chemical composition of a sampled rock which may have formed as a product of

mingling (hybridization), based on the field and textural evidence (Appendix 6:

Fig. A6-5). Thus, many of the CRIC rocks may be hybrids produced by the

incomplete mixing (i.e. mingling) of other magmas.

The field and textural evidence suggests that the CRIC spotted

hornblende gabbro can be produced by mingling (i.e. incomplete mixing) of

basaltic and tonalitic magmas. The modeling results require mixing of 2.5 parts of

hornblende gabbro with 1 part of tonalite, and the addition of 4% magnetite

(Appendix 6: Fig. A6-6, 9A); the necessity to add magnetite is problematic and

underlines the complex petrogenetic processes which were at play during

emplacement and crystallization.

CRIC quartz hornblende diorite failed to be related to the parental gabbro

by simple fractionation. Instead, mixing of three magmas (1 part tonalite : 1 part

109

hornblende gabbro : 1 part hornblendite) can produce a quartz hornblende diorite

composition (Appendix 6: Fig. A6-7).

CRIC chilled mafic enclaves of hornblende diorite, tonalite and

trondhjemite failed to be correlated with the parental gabbro, or among

themselves, through simple crystallization modeling (Appendix 6: Figs. A6-9B,

10), which suggests a more complex or completely different paragenesis.

In the LCIC, all sampled hornblende gabbroic intrusions failed to be

related to a parental hornblende gabbro by simple crystallization modeling

(Appendix 6: Fig. A6-11). This may be expected, as chosen parental hornblende

gabbro might be a product of mixing itself, as well as other hornblende gabbroic

intrusions. The only relatively successful curve fitting was produced by relating

tonalite to trondhjemite by the following fractionation trend: plagioclase >

clinopyroxene > magnetite (Appendix 6: Fig. A6-12).

Results of trace element modeling appear to be inconsistent with the

results from major oxides modeling that show a correlation between the Conuma

River parental gabbro to hornblendite varieties. Two of the hornblendite varieties:

DM05-212A and KF07-M2 are shown in Appendix 6: Fig. A6-4. Trace element

compositional curves do not show a good match. Instead extreme spikes,

especially for P, Ti, V and Ni in hornblendite samples, contrast with the rather

smooth and straight shape of the modeled trace element curves. The absence of

(expected) smoother trace element patterns is perplexing, but has not been

examined further in this thesis.

110

10.2 Crystallization modeling results from basalts, olivine and plagioclase cumulates of Port Renfrew area (Bonanza arc)

“Olivine cumulates” from the Port Renfrew area, as described by Larocque

(2008), appear to resemble olivine hornblendites from the Conuma River locality.

The similarity lies in their field occurrence, contemporaneity with Jurassic

intrusions, types and proportions of present phases, texture and geochemistry.

According to Larocque (2008), hornblende contained in the cumulates was an

early crystallizing phase. Similarly, Larocque (2008) suggested that hornblende

fractionation from primary basaltic magmas yielded basaltic andesite, which

approximates a bulk crustal composition and played an important role in the

evolution of Bonanza arc crust.

Larocque (2008) concluded that 30-45% hornblende fractionation was

required to shift the basalt composition to the bulk crust of basaltic andesite

composition. His hypothesis was based largely on a graphical analysis of data on

binary graphs, the results of which contrast with the modeling of his data in this

thesis using Stonergrams. Specifically, hornblende as a fractionating or

accumulating phase was not determined by the Stonergram modeling (Appendix

6: Fig. A6-13A). Instead, the modeling determined that fractionation of mainly

clinopyroxene, plagioclase, orthopyroxene and subordinate olivine and magnetite

fits the data more closely (Appendix 6: Fig. A6-13B). Similarly, Stonergram

modeling showed that the Port Renfrew olivine cumulate was not related to a

parental basalt composition by accumulation of hornblende (Appendix 6: Fig. A6-

14A). Instead, the cumulates were more accurately modeled by the addition of 5

parts of mineral phases (olivine, orthopyroxene, magnetite and minor plagioclase

111

and clinopyroxene) to 1 part of parental basalt (Appendix 6: Fig. A6-14B). A good

curve fit was also achieved relating the same basaltic parent to Port Renfrew

plagioclase cumulates by accumulation of 3.4 parts of crystals (plagioclase,

clinopyroxene, magnetite) to 1 part of parental basalt (Appendix 6: Fig. A6-15).

10.3 Crystallization modeling results from gabbroic rocks of the Port Alberni region (Bonanza arc)

Published geochemical data from the Port Alberni region was modeled to

find relations between Bonanza arc plutonic and volcanic rocks (DeBari et al.

1999). A genetic link was suggested by similarities found in whole rock and trace

element geochemistry, Sr and Nd isotope signatures and in geochronology.

Crystallization modeling was successful in relating two samples of gabbro

from the Broken Islands via accumulation of 1.5 parts of crystals (clinopyroxene,

plagioclase, magnetite and minor orthopyroxene) into 1 part of “parental”gabbro

(Appendix 6: Fig. A6-16).

10.4 Crystallization modeling results from basaltic and gabbroic rocks from Tazlina Lake (Talkeetna arc)

The Talkeetna island arc section, exposed in the south-central Alaska,

consists of six major units, including the upper mantle harzburgite overlain by

pyroxenite and lower gabbroic rocks, mid-crustal upper gabbroic, dioritic and

tonalitic rocks, and capped by evolved volcanic rocks of basalt to rhyolite

compositions (Greene et al. 2006). The workers found a link between calculated

primary magma compositions and evolved Talkeetna volcanic rocks through

fractionation of 25% pyroxenite at the base of the arc crust. Through a few steps

112

in crystallization modeling they show a shift from primary basaltic composition to

an andesitic one.

An attempt in this thesis to simulate all steps in their crystallization

modeling failed due to an incomplete published data set. Only the data from the

first step of the crystallization modeling was available in published format. This

step shows a shift from a primary basaltic composition to an evolved basaltic

composition by 20.7% fractionation of 42.9% clinopyroxene, 31.6% plagioclase,

17.5% Mg-Al spinel and 8% orthopyroxene (Greene et al. 2006). When testing

this hypothesis with Stonergram modeling, (Appendix 6: Fig. A6-17A), a poor fit

was achieved. An improved fit was provided by a model consisting of 50%

fractionation (which means that 0.5 parts of crystals need to be removed from 1

part of liquid) of clinopyroxene>plagioclase>olivine>magnetite and minor

orthopyroxene (Appendix 6: Fig. A6-17B). This result suggests that both the

Bonanza and Talkeetna arcs evolved by fractionation of similar mineral

assemblages.

10.5 Summary and discussion of crystallization modeling

In the search for a parental magma composition in the Conuma River

locality a non-cumulate gabbro with high Mg# and Fo% was selected to

represent the parent magma. Its Mg# and Fo% values could mean that the

chosen parental sample has a real parental composition or even a near-primary

magma composition, whose sum of its fractionated products can be represented

by CRIC hornblendites, hornblende gabbros/diorites and tonalites. It is also

possible that the chosen parental sample represents an evolved fraction of the

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unknown parental liquid composition. In such a scenario, the chosen parental

sample may represent - together with CRIC hornblendites, hornblende

gabbros/diorites and tonalites - some of the fractionated products of the unknown

parental magma.

Crystallization modeling of geochemical data from the CRIC intrusions

revealed that hornblendite varieties are genetically linked to the most abundant

intrusion in the area: parental plagioclase phyric, quartz-hornblende gabbro.

Difficulty in finding a genetic link between hornblende gabbro cumulates

alternating with hornblenditic sheets suggests that these gabbros may have no

common origin with hornblendites or the parental gabbro. This may exclude their

origin via in-situ fractionation within a layered structure, but need not exclude

their cogenetic link to hornblendites and parental gabbro via fractionation and

accumulation prior to emplacement, assuming that their original geochemical

signature became complicated by, for example, mixing and assimilation

processes prior to, and during, their emplacement.

Crystallization modeling suggests no genetic link between other CRIC

hornblende gabbro and hornblende diorite varieties. No amount of simple

fractionation can produce tonalite or trondhjemite from parental gabbro. Tonalite

and trondhjemite cannot be related to one another by a simple fractionation

either. As such, the tonalite is interpreted to represent a separate batch of

magma that served as a partially crystalline host intrusion for incoming pulses of

basaltic magmas from deeper levels of the crust, i.e., an ideal environment for

magma mingling and mixing processes. This idea is supported by some

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successful mixing models showing that certain hornblende gabbro varieties can

be produced by mixing of tonalitic (silicic) and olivine hornblenditic (basaltic)

magmas (Appendix 6: Figs. A6-5-7).

Intrusions from the LCIC failed to show any relation through simple

fractionation processes. This is expected based on the complex textural evidence

displayed by these intrusions, pointing to magma mingling and mixing.

Results from crystallization modeling indicate that the phases that played

a key role in the early fractionating history of the CRIC are dominantly olivine,

minor plagioclase, +/- clinopyroxene, and minor magnetite. By corollary, these

phases, with the addition of orthopyroxene, appear to be a key factor in

fractionation of Port Renfrew parental magmas. This modeling result is not

consistent with 30-45% hornblende fractionation from parental basaltic magma

causing a shift to a more evolved basaltic andesite composition, as suggested by

Larocque (2008).

Two Broken Island gabbros from the Port Alberni region can be related by

fractionation of plagioclase, clinopyroxene and magnetite. A similar situation is

evident in the Talkeetna arc that is located today about 1000 km to the north of

the Bonanza arc. Here, early fractionating phases of Tazlina Lake magmas

included clinopyroxene, plagioclase, olivine, orthopyroxene and magnetite.

Results from this modeling are inconsistent with a large proportion of Mg-Al

spinel in the fractionation assemblage as suggested by Greene et al (2006).

It appears from the previous published work that both arcs are connected

by a temporal and geochemical link. Olivine, plagioclase, pyroxene and

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magnetite play an important role in the early crystallization history in both arcs.

An early fractionation of magnetite suggests a calc-alkaline trend of these arc

magmas. Appearance of orthopyroxene in the early fractionating history may

suggest that these arc magmas are water bearing, but not water saturated.

Hornblende seems to play no role in this evolution as it is a minor magmatic

phase and often a secondary phase.

Pearce element ratios present graphically fractionating phases controlling

the evolution of CRIC arc magmas. They show that CRIC samples define a very

strong olivine fractionation trend, which is confirmed by crystallization modelling

(Figs. 46 and 47B).

CRIC samples also plot between clinopyroxene, hornblende and

plagioclase fractionation vectors (Figs. 46 and 47A). As the hornblende can be

excluded from a group of early fractionating phases, only clinopyroxene and

plagioclase come into consideration. Data shows affinity to plagioclase

fractionation, but it does not follow a clearly parallel trend.

(FeO*+MgO)/SiO2 Al2O3/CaO

Data slopes 2.0445 0.8068

Olivine 2.04 0

Orthopyroxene 1.01 0

Clinopyroxene 0.39 0

Hornblende 0.72 0.56

Plagioclase 0 1.05

0

0.5

1

1.5

2

2.5

0 0.5 1 1.5 2 2.5

Al2O3/CaO

(Fe

O*+

Mg

O)/

SiO

2

clin

op

yro

xen

e

clinopyroxene

hornblende

ho

rnb

len

de

olivine

orthopyroxene

pla

gio

cla

se

DATA SLOPES

Pearce element ratio diagram for Conuma River intrusions linked through fractionation process

Figure 46. Pearce element ratio diagram-Conuma River intrusions. A table with major oxide ratios (mol%) in fractionating phases, based on the microprobe data and data slopes values from normalized, anhydrous major oxides in fractionating suite from Conuma River locality, derived from plots FeO*+MgO vs SiO2 and Al2O3 vs CaO (not

shown). Data is plotted below the table.

116

y = 0.8068x + 0.1006

R² = 0.865

0.3

0.5

0.7

0.9

1.1

1.3

0.3 0.4 0.5 0.6 0.7 0.8

Pearce element ratio plot for Conuma River intrusionsCaO vs Al2O3

clinopyroxene fractionation

Al 2

O3

CaOA

y = 2.0445x - 3.9836

R² = 0.9276

0

1

2

3

4

5

0 2 4 6 8 10

Pearce element ratio plot for Conuma River intrusionsFeO* + MgO vs SiO2

Fe

O*

+ M

gO

SiO2B

Figure 47. A: Pearce element ratio plot Al2O3 vs CaO shows trend of Conuma River samples that is not parallel with any of the phase fractionation vectors. B: Pearce element ratio plot FeO*+MgO vs SiO2 shows a perfectly parallel trend of Conuma River fractionating suite with olivine fractionation vector.

It is a difficult task to characterize in more detail Bonanza arc magmas

parental to CRIC and Port Renfrew intrusions, especially when this study focused

on plutonic rocks produced by numerous and complex processes, and whose

parental magmas composition became a subject of numerous and complex

modifications. In the attempt to put some reasonable general geochemical

constraints on the parental magma composition, by utilizing all outcomes of this

research, the results of experiments with high Mg basalts from the Lesser Antilles

arc (Pichavant and McDonald 2007) seem to be relevant and applicable to

magma paragenesis in the Conuma River and Port Renfrew areas.

Following the Pichavant and McDonald (2007) experiments, a partial

melting of mantle peridotite in the mantle wedge would generate primary

magmas, or after a certain amount of chemical interaction, near-primary high Mg

basaltic magmas. In experiments, such a magma composition with a water

content of 1.5 wt% can be in equilibrium with mantle peridotite at 1.5 log units

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below and 2.3 log units above the NNO buffer at 1235oC, at a crystallization

pressure of 11.5 kbar (Pichavant and McDonald 2007). These near-primary high

Mg basaltic magmas would then ascend through the mantle and become

emplaced in the lower arc crust, where they may undergo an early partial

fractionation of olivine, pyroxene, plagioclase and magnetite (in accordance with

extrapolated Talkeetna arc results), shifting the magma composition to basaltic

andesite.

Basaltic andesite magmas could then represent parental magmas to

Conuma River and Port Renfrew olivine hornblendites. By fractionating

dominantly olivine, orthopyroxene, and minor plagioclase and clinopyroxene (in

accordance with petrographical analysis), the residual liquids would evolve to

more evolved basaltic andesites, and the fractionated crystals would accumulate

to form ultramafic cumulates such as the Conuma River and Port Renfrew

hornblendites. This is scenario is comparable, as shown in experiments

(Pichavant and McDonald 2007), to a near liquidus crystallization of olivine +

orthopyroxene + clinopyroxene + plagioclase and magnetite under 4 kbar

crystallization pressure, at the range of 0.8 below and 2.4 log units above the

NNO buffer at 1160-1060oC and a water content between 2-4 wt%.

Orthopyroxene stability under these conditions is also affected by SiO2 content,

which needs to be more than 53 wt% (Pichavant and McDonald 2007).

Fractionating mineral assemblages of CRIC and Port Renfrew

hornblendites from the composition of evolved basaltic andesite would shift

residual liquid compositions toward more evolved basaltic andesites, which can

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be now represented by the Conuma “parental” gabbro intrusion. Al and Mg

contents of the “parental” gabbro intrusion are also suggestive of such a

paragenesis and of having a common parent with earlier fractionating products:

CRIC and Port Renfrew hornblendites.

Lastly, magma mixing, mingling and assimilation processes are likely to

have been involved in the genesis of the Conuma River and Leagh Creek

intrusive rocks of intermediate composition.

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11: TECTONO-MAGMATIC MODEL

A tectono-magmatic model is presented that incorporates the field,

petrographical, mineralogical and lithogeochemical analyses in combination with

results from crystallization modeling. It is a simplified conceptual model that

represents a possible scenario for arc magma paragenesis and tectonic

processes in the Bonanza arc setting during the Early to Middle Jurassic.

11.1 General conceptual model for the Bonanza Arc

Primary arc magmas are generated at subduction zones by partial melting

of mantle peridotite (Fig. 48). After a sufficient amount of magma has

accumulated (>15%), the melt coalesces to form a large magma body, which

generally rises as diapirs or nested diapirs because it is less dense than the

surrounding mantle (Murphy 2007). During its ascent, the magma cools,

densifies and changes its composition through the interaction with the

surrounding mantle to become a near-primary magma (Murphy 2007). Due to an

increase in density, this near primary magma may underplate at the Moho, or

continue its ascent by exploiting fractures in the arc crust (Murphy 2007; Winter

2000). Fracture exploitation by magma would allow for a fast ascent (adiabatic

rise), and help retain the heat and chemical composition of near-primary magmas

(Murphy 2007). The fractures could be associated with extensional and/or strike-

slip faults that are common in an arc setting (Murphy 2007). Some of the near-

primary magmas could be emplaced within deeper crustal levels where they

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would undergo early crystallization of olivine, clinopyroxene, plagioclase and

magnetite, similar to the crystallization modeling of the Talkeetna arc basalts

near Tazlina Lake that may be extrapolated to the deeper crustal environment

postulated for the Bonanza arc of this study (Fig. 48). Residual evolved basaltic

and basaltic-andesite liquids are emplaced into the mid-crustal levels and

experience their own fractionation and differentiation. The CRIC and LCIC may

serve as examples of crystallized magmas that were fractionating, mixing and

mingling in the mid-crustal environment during the development of the Bonanza

arc (Fig. 49A, C).

11.2 Conceptual model as it applies to the CRIC

In the CRIC, the host tonalite intrusion is deemed to have undergone slow

cooling in the hot, mid-crustal arc environment. The source of the tonalite magma

is unknown (possibly a crustal melt), and does not appear to be genetically

related to the underlying voluminous intrusion of basaltic andesite composition.

The basaltic andesite intrusion is thought to have fractionated into ultramafic,

mafic and intermediate layers; the ultramafic units were deposited on the bottom

of a magma chamber and were overlain by more evolved mafic and even more

evolved intermediate units. Dilational cracks are thought to have opened in the

overlying, partially consolidated tonalite in response to an intra-arc extensional

regime (Figs. 49B and 50A). Decompression is likely accompanied the opening

of fractures, which triggered the ascent of the underlying fractionating magmas

(Fig. 50B). Cracks in the tonalite were then filled with evolved basaltic liquid,

basaltic crystal-poor magmas and basaltic crystal-mushes. This event could have

121

caused partial melting of the tonalite, convection of the tonalite mass and

mingling of the tonalite mush with incoming basaltic magmas. Products of these

events would be stocks and enclaves of mafic to intermediate intrusive varieties

such as hornblende gabbros and hornblende diorites that originated by

fractionation or by a combination of fractionation and magma mingling (Figs. 50B,

C). This event would also be accompanied by mobilization of basaltic magma

mushes (“hornblenditic” magmas), which might have moved to higher crustal

levels, previously occupied by gabbros and diorites (Fig. 50C). The magmatic

activity slowly deceased and the more voluminous intrusions likely had enough

time to cool until they were nearly solidified. Reopening or creating new cracks in

almost consolidated gabbro, diorite and tonalite created free ascent paths for the

underlying –mobilized- basaltic magma mushes (“hornblenditic” magmas) that

filled the fractures (Fig. 50D). This event would cause limited partial melting of

host gabbros and diorites, and would be increasingly effective in melting the

tonalite, which would become remobilized again and begin flowing. As a result,

products of this event would include layered intrusions and disruption of earlier,

semi-solidified mafic intrusions, which would become incorporated into the

tonalitic flowing mass, and would be stretched, abraded and marginally

commingled with tonalite (Fig. 50D). Short-lived shear could explain the flow

structures preserved within the layered intrusions prior to their consolidation.

Continued magmatic activity likely led to new pulses of hot mafic magmas

into the same locus- the cooling intrusive environment; thus producing the

observed chilled mafic enclaves with the acicular hornblende texture within

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tonalite. These pulses differed from each other by volume, degree of

crystallization and chemical composition. Their geochemical composition reflects

an arc tholeiitic affinity and their source is unknown.

Subsequently, Jurassic to Eocene magmatic activity into the same locus

resulted in formation of numerous small stocks and dykes of tonalite and

hybridized diorite compositions that brecciated solidified intrusions (Fig. 4).

11.3 Conceptual model as it applies to the LCIC

The LCIC reflects magmatic activity with no observed distinct tectonic

structure (Fig. 49C). This activity is characterized by extensive magma

commingling and it records a number of commingling events.

In the LCIC, a tonalitic intrusion is thought to have differentiated from an

unknown source, possibly a crustal melt, and was emplaced at middle crustal

levels (~12 km) (Fig. 51A). Initially it was a crystal-poor intrusion, and

subsequently experienced over-pressurized injection of hot basaltic arc magmas

of tholeiitic affinity. Mingling of silicic and basaltic magmas took place by

dispersion of basaltic magma into the hot tonalitic host, followed by flow in the

mingled magmas that could have led to even more disintegration of the

dispersed basaltic pockets within the tonalite (Fig. 51B). These processes in

combination with a slight degree of undercooling of basaltic droplets within the

hot tonalite may explain the formation of the observed spotted hornblende

gabbro/ hornblende diorite texture (Fig. 51C).

123

Decompression could have allowed the spotted hornblende diorite

intrusion to migrate as a crystal mush into higher levels of the crust and

emplaced into the Karmutsen Formation. The intrusion was then subjected to

contemporaneous, smaller volume basaltic pulses that mingled with it. These

magma batches chilled against the spotted hornblende gabbro/hornblende diorite

intrusion forming magmatic enclaves with acicular hornblende texture (Fig. 51D).

Another contemporaneous, voluminous intrusion of unknown origin and

source (Fig. 8) is hybridized diorite. This intrusion became the host to later

basaltic pulses that are interpreted to have formed magmatic enclaves displaying

pillow-like structures (analogous to Fig. A1-19D).

Subsequently, Jurassic to Eocene magmatic activity also produced

numerous plagioclase phyric melanocratic dykes with aphanatic andesitic

groundmass and tonalitic dykes and stocks that can be found within the LCIC.

Some of these tonalitic intrusions could be genetically related as suggested by

crystallization modelling (Fig. 51D).

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Figure 48. Generalized tectono-magmatic model for the formation of the Bonanza arc, which includes the CRIC and LCIC. Magma generation resulted from partial melting of the mantle peridotite. Early fractionation of basaltic magma takes place at deep crustal arc levels (Depth ~20-30 km). The white square inset represents the approximate mid-crustal location of CRIC and LCIC within the Bonanza arc setting as shown in Fig. 50.

125

Figure 49. Enlargement of the solid white inset from Fig. 49 representing a focus on mid-crustal location of CRIC and LCIC within the Bonanza arc setting. The dashed white squares in the Conuma River locality outline the locations of the representation of CRIC tectono-magmatic model in Fig. 51. The dotted white square in the Leagh Creek locality outlines the location of the representation of LCIC tectono-magmatic model in Fig. 52. A: TIME 1 in Conuma River locality-Jurassic intrusions represents the period prior to major tectonic stresses. B: TIME 2 in Conuma River locality-Local pull-apart structures formed in response to an intra-arc extensional regime in the Conuma River locality, creating pathways for the ascent of fractionating basaltic magmas ponded below. C: TIME 1in Leagh Creek locality-Jurassic intrusions represents the time period prior to the introduction of new magmatic pulses.

126

Figure 50. A close-up of a white dashed square of Fig. 50A, B showing mid-crustal levels of the Bonanza arc in the Conuma River locality. A: TIME 3-Magma body, beneath the solidifying tonalite, fractionated and differentiated. After pull-aparts developed, underlying magma exploited the fractures in the nearly consolidated tonalite. This underlying magma was a top part of the fractionating sequence within the fractionating basaltic magma body. Consolidated ultramafic cumulates formed at the bottom part of the magma body, these were followed by an ultramafic crystal mush that later produced “hornblendite” varieties found in CRIC. An ultramafic crystal mush would be overlain by crystal poor mafic (basaltic andesite composition) magmas that later produced “hornblende gabbro” varieties, including the “parental gabbro” found in CRIC. B: TIME 4-Hot basaltic magma intruded and partially melted the tonalite, inducing convective flow in the tonalite.

127

Figure 50. (Continued). C: TIME 5-Basaltic magma differentiated, filled fractures in the partially solidified tonalite, mingled with it and produced numerous intrusive varieties of mafic to intermediate compositions. These basaltic magma pulses in tonalite slowly cooled and formed medium to coarse grained, partly crystallized (i.e. partly solid) magmatic enclaves in tonalite until the onset of a new magmatic activity. New basaltic pulses supplied heat and kept the tonalite flowing. Convecting tonalite disrupted margins of earlier, now partly crystallized basaltic magmatic enclaves and dismembered them, preserving magmatic flow. D:TIME 6-Reactivation of cracks in newly consolidated mafic and tonalitic intrusions created pathways for ultramafic crystal mushes that filled the cracks, resulting in a layered structure (white rectangle) causing partial recrystallization of hornblende gabbro layers. Continuous magmatic pulses into the relatively cooler but still convecting tonalite resulted in the formation of new magmatic enclaves, preserving chilled textures and magmatic flow (blue rectangle).

128

Figure 51. A close-up of white dotted square inset in Fig. 50C showing mid-crustal levels of the Bonanza arc in the Leagh Creek locality. A: TIME 2-Tonalite magma cooled slowly, forming solidified margins inward. B: TIME3-A new voluminous basaltic injection entered a crystal-poor tonalite and due to its high temperature, low viscosity and high pressure was dispersed in the tonalite. The new volume of magma caused fracturing of the tonalitic magma chamber, which allowed both magmas to escape into the surrounding country rocks; some of the mingled magmas started migrating into the higher crustal levels.

129

Figure 51. (Continued). C: TIME 4-The heterogeneous dispersion of basaltic magma in silicic magma resulted in the spotted hornblende gabbro mingling texture. Some locations, especially close to a conduit produced minimally mingled hornblende gabbro. Crystal mush of mingled magmas was emplaced in the Karmutsen Formation. D: TIME 5-Numerous new basaltic pulses intruded mingled and solidifying tonalitic and basaltic magmas, supplied a new source of heat and caused convection in the hybridized host intrusion; intrusion of the new basaltic pulses into relatively colder hybridized intrusion produced magmatic enclaves with chill textures that include medium- to fine-grained acicular hornblende diorite and basaltic pillow-like enclaves. Jurassic to Eocene tonalites and trondhjemite cut across the intrusive complex.

130

CONCLUSIONS

The Conuma River and Leagh Creek intrusive complexes serve as

windows into the Early to Middle Jurassic mid-crust of Bonanza arc. This

environment exhibits numerous hornblenditic, gabbroic, dioritic and tonalitic

intrusions; layered and flow structures; magmatic ultramafic and mafic enclaves

with or without chill textures; magma mixing and mingling textures; temporal,

spatial, shape- and volume- variations in intrusions; abrupt and gradational

contacts between intrusions; and pegmatites.

The ultramafic varieties contain olivine, orthopyroxene and abundant

hornblende and do not contain quartz and alkali feldspar. The most felsic

varieties contain quartz, alkali feldspar and abundant plagioclase and do not

contain olivine and orthopyroxene. However, all mafic and intermediate varieties

contain hornblende and plagioclase of varying proportions. The dominant

textures are porphyritic/ poikilitic/ xenoporphyritic (i. e. mingling textures). Also

present are less dominant equigranular textures. Additional textures are

characterized by acicular and spotted hornblende. The acicular hornblende

texture is interpreted to form as a result of chilling of newly injected hotter magma

against the cooler host magma (i. e. magma mingling). Spotted hornblende

texture is interpreted to form as a result of vigorous stirring of silicic and basaltic

crystal mushes in the contact zone or as a result of incomplete mixing (i. e. a

131

high degree of mingling) of silicic and basaltic magmas due to a slight

temperature gradient.

The post-intrusion metamorphic assemblage of chlorite, epidote and

actinolite indicates low metamorphic greenschist facies. The alteration

assemblage includes hornblende, biotite, anthophyllite, chlorite, sericite,

sausserite, serpentine, iddingsite, calcite and iron oxides.

Two new Ar-Ar dates indicate an Early to Middle Jurassic age for

intrusions from each of the complexes. The nature of the contacts indicates a

contemporaneity of intrusions within the complexes.

The thermobarometry is not well constrained due to a lack of appropriate

mineral assemblages and post emplacement alteration, although, yields some

constraints consistent with mid-crustal levels.

Whole rock geochemistry points to a calc-alkaline signature of majority

Conuma River intrusions and tholeiitic signature of Conuma River and Leagh

Creek chilled mafic enclaves, all consistent with a subduction zone setting. The

trace element patterns resemble patterns of arc magmas and suggest a

cogenetic link between the intrusions, especially between the hornblenditic

intrusions.

Crystallization modeling shows a cogenetic link between the Conuma

River cumulate hornblendites and non-cumulate hornblende gabbros.

Crystallization modeling shows that the hornblendites are best modeled by

accumulation of dominantly olivine with subsidiary plagioclase, clinopyroxene

132

and magnetite. Hornblende was not an important phase in the control of magma-

paragenesis. Hornblende is interpreted as 1) a product of high temperature late

stage interstitial melt, 2) a product of mineral-melt discontinuous reactions (ol + pl

+ melt hbl), and 3) a product of solidus reaction (cpx + fluid hbl). Pearce

element ratio (MgO*+ FeO vs SiO2) plots suggest the dominating fractionating

phase, olivine, controlled the evolution path of the liquid composition between

non-cumulate hornblende gabbro and hornblendites from the Conuma River

locality.

The remainder of the intrusions within both complexes formed from

magmas that experienced more complicated paragenesis, which involved mixing,

mingling and assimilation processes. Field observations reveal an incomplete

mixing (mingling) of basaltic and silicic magmas, complemented by results from

crystallization modeling.

Olivine, minor plagioclase, +/- clinopyroxene and magnetite played a key

role in the early crystallization history of the Conuma River and Port Renfrew

magma paragenesis in the Bonanza arc. From a regional perspective, the same

mineral assemblage appears to be an important aspect in the evolution of the

Tazlina Lake magmas of the Talkeetna arc.

The Conuma River layered hornblendite and hornblende gabbro intrusions

are indicative of layered structures formed in a pull apart, extensional intra-arc

tectonic regime, and consequently, similar free ascent paths for arc magmas may

be observed elsewhere in arc environments similar to the Bonanza arc. The flow

structures observed within the layered intrusions could originate by successive

133

emplacements of the basaltic crystal mushes into fractured gabbros, followed by

short-lived readjustments in the form of shearing.

Although all intrusions of both complexes appear compositionally to be

products of fractionating magmas, based on crystallization modeling,

hornblendites appear to be products of fractionation and seem to be the least

affected by magma mingling. It is very likely though that all mafic and

intermediate intrusions are to some degree products of fractionating magmas,

but during the later mobilization, became subjected to mixing and assimilation

processes prior to and during emplacement and to mingling processes during

and after emplacement. Numerous mafic and intermediate stocks and magmatic

enclaves within vein-networked intrusive hosts -in both complexes- are products

of multiple injections of mafic and intermediate magmas into partially melted

hosted intrusions.

Suggested further work to give more insight into Jurassic arc magmatism

may include zircon dating to determine precise timing of intrusive events; isotope

studies of Rb-Sr, Sm-Nd to elucidate the source of evolved magmas; 143Nd/144Nd

and 87Sr/86Sr isotope ratios to determine the extent of subducted sediments, and

melt inclusion studies in olivine to calculate the water content of the magma.

134

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145

APPENDIX 1: FIELD RELATIONS

Table A1- 1. List of samples from Gold River area (NTS 092E/16).

Conuma River intrusive complexOutcrop ID Sample ID Eastings Northings Lithology Intrusion type Geochemistry Assay Thin section Ar-Ar age Microprobe SEM H Sketch Field Photo

07-A DM 05-212A 687603 5529523 olivine hornblendite sheet X X X X X X X X X

07-A DM 05-212C 687603 5529523 hornblende gabbro sheet X X X X X X X X

07-A KF 07-A3 687603 5529523 olivine hornblendite sheet X X X X X X X X

07-A KF 07-A4 687603 5529523 hornblende gabbro sheet X X X X X X X X

07-A KF 07-A6/A7 687603 5529523 hornblende gabbro sheet X X X X

07-A KF 07-A8a 687603 5529523 olivine hornblendite sheet X X X X

07-B KF 07-B4 687613 5529636 olivine hornblendite sheet X X X X X

07-C K07-C 687631 5529639 hornblende gabbro stock X X

07-D KF 07-D4 687672 5529659 trondhjemite stock X X X X X

07-D KF07- D5 687672 5529659 hornblende diorite mafic enclave X X X

07-D KF 07- D7 687672 5529659 hornblende diorite mafic enclave X X X X

07-E KF 07-E1 687631 5529590 olivine hornblendite sheet X X X X X X X

07-F KF 07-F1 687623 5529571 hornblende diorite stock X X X X X X X

07-F KF 07-F2 687623 5529571 hornblende diorite sheets? X

07-G K07-G 687655 5529552 hornblende gabbro stock X

07-H K07-H 687636 5529437 hornblende gabbro stock X

07-I KF 07-I3 687595 5529487 basalt dyke X X

07-I KF07-I 687702 5529293 olivine hornblendite sheet X X X

07-J KF 07-JN1 687583 5529367 olivine hornblendite sheet X X X X X X X X

07-J KF 07-JN2 687583 5529367 olivine hornblendite sheet X X X X X X

07-J KF 07-JN3 687583 5529367 hornblende gabbro sheet X X X X X X

07-J KF 07-JS 687583 5529367 olivine hornblendite sheet X X X

07-K K07-K 687551 5529225 hornblendite sheet X X X

07-L KF07-L1 687512 5529053 hornblende diorite stock X X

07-M KF 07-M2 686944 5529329 hornblendite stock X X X X X X

07-P KF07-P 687356 5528858 hornblende gabbro stock X X X X

07-Q KF 07-Q2 687565 5529582 olivine hornblendite sheet X X X X X

07-R KF 07-R2 687663 5529189 hornblende diorite stock X X X X X

07-S K07-S 687575 5529125 hornblende diorite mafic enclave X

08-01 KF 08-01 686984 5529176 hornblende gabbro mafic enclave X

08-02 KF 08-02 687097 5529162 hornblendite hornblendite X

08-03 KF 08-03 687097 5529162 hornblendite hornblendite X

08-08 KF 08-08 687034 5529024 hornblende gabbro mafic enclave X

08-10 KF 08-10 686959 5528764 tonalite stock X X X X X

08-11 KF 08-11 686869 5528690 basalt country rock septa X

08-11 KF 08-11B 686869 5528690 hornblende diorite mafic enclave X X

08-12 KF 08-12 686771 5528589 basalt country rock septa X X

146

Table A1- 1. (Continued).

Conuma River intrusive complexOutcrop ID Sample ID Eastings Northings Lithology Intrusion type Geochemistry Assay Thin section Ar-Ar age Microprobe SEM H Sketch Field Photo

08-15 KF 08-15 688437 5529066 hornblende gabbro mafic enclave X X

08-16 KF 08- 16 688483 5529064 hornblendite sheet X X X X

08-17 KF 08-17 688672 5528986 hornblende gabbro sheet? X

08-19 KF 08-19 689496 5528879 hornblende gabbro stock X

08-20 KF 08-20 689311 5528840 hornblende gabbro stock X X


08-28 KF 08-28 687914 5528523 hornblende gabbro stock X X X

08-30 KF 08-30 687602 5528681 hornblende gabbro stock X X X




08-35 KF08-35 686758 5528577 basalt country rock septa X X X

Leagh Creek intrusive complexOutcrop ID Sample ID Eastings Northings Lithology Intrusion type Geochemistry Assay Thin section Ar-Ar age Microprobe SEM H Sketch Field Photo

07-07 KF07-07 690237 5522615 hornblende gabbro stock X X

07-08 KF07-08 690379 5522708 hornblende gabbro stock X

07-37 KF08-37 685370 5522143 basalt country rock septa X X X

07-38 KF08-38 685575 5522262 basalt country rock septa X

06-38 DM 06-38 687662 5522811 hornblende diorite stock X X X X

08-40 KF08-40-7 686150 5522830 hornblende gabbro stock X

08-40 KF08-40-13 686184 5522841 hornblende gabbro stock X X


08-40 KF08-40-19 686280 5522863 hornblende gabbro stock X X

08-40 KF08-40-21A 686295 5522863 hornblende diorite mafic enclave X X X

08-40 KF08-40-21B 686295 5522863 hornblende diorite stock X X X

08-40 KF-08-40-21C 686295 5522863 hornblende diorite stock X X X




08-41 KF08-41 687182 5522955 hornblende gabbro stock X X X

06-41 DM06-41 688971 5524016 hornblende gabbro stock X




08-50 KF08-50 687748 5523188 tonalite dyke X


08-52 KF08-52A 688336 5523613 trondhjemite stock X X X X

08-52 KF08-52B 688336 5523613 tonalite stock X X X X


147

Table A1- 2. Selected intrusive lithological types from Gold River area (NTS 092E/16) - hornblendite varieties.

HORNBLENDITE VARIETIES

PLAGIOCLASE-BEARING, PHLOGOPITE-PYROXENE-OLIVINE HORNBLENDITE

(abbreviation: Olivine hornblendite)

Very coarse-grained variety: Green-brown, rusty-brown, tan, flaky and pitted

weathering, black- green fresh, isotropic, hypidiomorphic, magnetic, phaneritic

rock with 90% interlocking, blocky, 1-2 cm black-dark green, randomly oriented

hornblende megacrysts and 10% platy, 5-10 mm light brown phlogopite. A

hornblende megacryst can contain up to 50% inclusions of 0.5-1 mm light green

olivine > pyroxene > rare plagioclase. The rock shows no reaction with HCl.

Colour index: 100

Photo: weathering surface; arrow points to one of the hornblende megacrysts

HORNBLENDE MEGACRYSTIC, PLAGIOCLASE-PHLOGOPITE HORNBLENDITE

(abbreviation: Megacrystic hornblendite)

Medium-grained variety with 20% hornblende megacrysts: Spheroidal-flaky-

pitted rusty-grey-green weathering, medium grey-green fresh, hypidiomorphic,

magnetic to non-magnetic, phaneritic rock with 75--80% randomly oriented

prismatic 3-5 mm black hornblende and 10% lightly epidotized (light green) white

plagioclase either as 0.5-1 mm inclusions in the hornblende megacrysts or as 2-

3 mm prismatic crystals and 5-10% platy, interstitial, 1-3 mm light brown-silvery

biotite intergrown with hornblende. Hornblende megacrysts (max. 10 mm)

contain relicts of olivines. The hornblende megacryst abundance varies from 5-

90%.

Colour index: 100 Photo: fresh surface; arrows point to hornblende megacrysts

148


HORNBLENDITE VARIETIES

HORNBLENDE MEGACRYSTIC, PLAGIOCLASE-PHLOGOPITE HORNBLENDITE

(abbreviation: Megacrystic hornblendite)

Medium-grained variety with 5% hornblende megacrysts: Spheroidal-flaky-pitted

rusty-gray-green weathering, grey-green fresh, hypidiomorphic, magnetic to non-

magnetic, phaneritic rock with 75--80% randomly oriented prismatic 3-5 mm

black hornblende and 10% lightly epidotized (light green) white plagioclase either

as 0.5-1 mm inclusions in the hornblende megacrysts or as 2-3 mm prismatic

crystals and 5-10% platy, interstitial, 1-3 mm light brown-silvery biotite intergrown

with hornblende. Hornblende megacrysts (max. 10 mm) contain relicts of

olivines. The hornblende megacryst abundance varies from 5-90%.

Colour index: 100

Photo: polished surface; arrows point to rare hornblende megacrysts

PLAGIOCLASE-PHLOGOPITE HORNBLENDITE

(abbreviation: Hornblendite)

Medium-grained variety: Light brown-green, spheroidally weathering, medium

grey-green fresh, isotropic, hypidiomorphic, magnetic, phaneritic rock with 60%

3-5mm randomly oriented green and black prismatic hornblende crystals, 20%

slightly epidotized plagioclase either as 0.5-1 mm inclusions in hornblende or as

2-3 mm prismatic crystals and 20% 1-3 mm light brown, platy biotite. Hornblende

may contain relicts of ferromagnesian minerals.

Colour index: 100-90

Photo: polished surface

149

Table A1- 3. Selected intrusive lithological types from Gold River area (NTS 092E/16) - hornblende gabbro varieties.

HORNBLENDE GABBRO VARIETIES

HORNBLENDE GABBRO

Medium- to coarse-grained variety: Medium-green weathering, green-grey

fresh, isotropic, hypidiomorphic, non-magnetic, phaneritic rock with 60-70% 3-7

mm, sometimes up to 10 mm green hornblende and 30-40% 3-5 mm white

anhedral plagioclase. Plagioclase occurs as well as idiomorphic inclusions in

hornblende. It can be zoned with white cores and light grey rims and can

contain 0.2 mm inclusions of green hornblende. It can occur in clusters that can

reach 7 mm diameter and can also appear patchy or worm-like.

Colour index: 80-70

Photo: polished surface; sample shows ~ 30% plagioclase

HORNBLENDE GABBRO

Medium- to coarse-grained variety: Medium-green weathering, green-gray

fresh, isotropic, hypidiomorphic, non-magnetic, phaneritic rock with 60-70% 3-7

mm, sometimes up to 10 mm green hornblende and 30-40% 3-5 mm white

anhedral plagioclase. Plagioclase occurs as well as idiomorphic inclusions in

hornblende. It can be zoned with white cores and light grey rims and can

contain 0.2 mm inclusions of green hornblende. It can occur in clusters that can

reach 7 mm diameter and can also appear patchy or worm-like.

Colour index: 80-70

Photo: polished surface; sample shows ~ 40% plagioclase; arrow points to plagioclase

with hornblende inclusion

150

Table A1- 4. Selected intrusive lithological types from Gold River area (NTS 092E/16) - hornblende gabbro/hornblende diorite varieties.

HORNBLENDE GABBRO/ HORNBLENDE DIORITE VARIETIES

HORNBLENDE GABBRO/ HORNBLENDE DIORITE

Medium-grained variety with plagioclase clusters: Light green weathering, salt

and pepper fresh, hypidiomorphic, magnetic, phaneritic rock with 60% one mm

grey and white plagioclase and 3 mm in diameter plagioclase clusters of worm-

like appearance and 40% 0.5-2 mm black acicular-bladed hornblende.

Plagioclase shows oscillatory zoning and grey translucent cores with white rims;

some plagioclase cores are epidotized; plagioclase sometimes contains 0.2-0.5

mm hornblende inclusions; epitaxial growth of hornblende and plagioclase

present as well. Texture is likely an example of thorough magma mingling.

Colour index: 60-50

Photo: polished surface; white arrow points to plagioclase with hornblende inclusion;

grey arrow points to grey plagioclase core (with hornblende) and with white rims


Medium-grained variety with hornblende-plagioclase phenocrysts: Grey-green

weathering, white-grey fresh, hypidiomorphic, phaneritic rock consisting of

groundmass and phenocrysts. Groundmass consists of 75% 2-3 mm or 0.5-1

mm black hornblende and 25% white plagioclase with or without 15% 7-8 mm,

euhedral, green hornblende phenocrysts and 15% 5-6 mm tabular, white

plagioclase phenocrysts or clusters made of 2-3 smaller plagioclase crystals;

plagioclase phenocrysts are zoned and twinned, including blebs of 0.5 mm

anhedral hornblende or 4 mm euhedral, striated hornblende; plagioclase

phenocryst/clusters have a spotted or worm-like appearance. Colour index: 60

Photo: polished surface; arrow points to plagioclase cluster with hornblende inclusions;

circle encloses groundmass hornblende and plagioclase

151




Medium-grained variety with coarse spotted hornblende: Creamy white-green

weathering, light-green grey fresh, magnetic, phaneritic rock with up to 70%

5-10 mm rounded, blackish-green hornblende spots consisting of a few smaller

euhedral hornblende crystals that contain rounded plagioclase inclusions.

Medium-grained groundmass has a salt and pepper appearance and consists

of 12% randomly oriented euhedral white plagioclase, 8% grey quartz and 10%

blackish-green hornblende. Hornblende spots tend to be aligned to form

parallel layers.

Colour index: 50

Photo: weathered surface


Medium- to fine-grained variety with medium spotted hornblende: Creamy

white-green weathering, green-light grey fresh, magnetic phaneritic rock with

50% 5 mm rounded, black-green hornblende spots consisting of a few smaller

euhedral hornblende crystals that contain rounded plagioclase inclusions.

Medium- to fine-grained groundmass has a salt and pepper appearance and

consists of 12% randomly oriented euhedral white plagioclase, 8% grey quartz

and 10% black-green hornblende.

Colour index: 60

Photo: polished surface

152

Table A1- 5. Selected intrusive lithological types from Gold River area (NTS 092E/16) - hornblende gabbro/hornblende diorite varieties.



Medium-grained variety with plagioclase phenocrysts: Light green weathering,

salt and pepper fresh, magnetic, phaneritic rock with 60% 1 mm grey and

white plagioclase and 3 mm plagioclase clusters and 40% 0.5-2 mm black

tabular hornblende. Plagioclase shows grey translucent cores with white rims;

plagioclase cores are sometimes epidotized (apple green); plagioclase

contains sometimes 0.2-0.5 mm anhedral hornblende inclusions; plagioclase

crystals show occasionally oscillatory zoning with 4-7 zones; small

plagioclases are euhedral, clusters have wormy appearance; epitaxial growth

of hornblende and plagioclase in the plagioclase core has oscillatory zoning;

Colour index: 60

Photo: polished surface; arrow points to a plagioclase phenocryst

HORNBLENDE DIORITE

Fine- to medium-grained variety: Leucocratic weathering, grey fresh,

nonmagnetic, idiomorphic, phaneritic rock with 70-80% 1- 4 mm white

plagioclase and 30% 1-4 mm green hornblende;

Colour index: 40


153

Table A1- 6. Selected intrusive lithological types from Gold River area (NTS 092E/16) - hornblende diorite varieties.

HORNBLENDE DIORITE VARIETIES

HORNBLENDE DIORITE

Fine- to medium-grained variety with acicular hornblende: Light pink-medium

grey weathering, salt and pepper fresh, magnetic, idiomorphic, equigranular

phaneritic rock with 60-80% 0.5-4 mm acicular, preferentially or randomly

oriented, green hornblende, 20–30 % 0.5-2 mm white plagioclase and 0-20%

1-2 mm quartz. 5-15% 2-5 mm xenocrysts of tabular feldspar > quartz >

hornblende; quartz and feldspar are sometimes rimmed by hornblende needles

or have a feldspar rim present and distributed randomly, or concentrated in

marginal zones of enclaves.

Colour index: 40


HORNBLENDE DIORITE

Medium-grained variety with acicular hornblende: Light pink-medium grey

weathering, salt and pepper fresh, magnetic, idiomorphic phaneritic rock with

60-80% 1-4 mm acicular, preferentially or randomly oriented, green

hornblende, 20–30 % 1-2 mm white plagioclase and 0-20% 1-2 mm quartz.

Commonly found in association with the spotted hornblende variety and

medium-grained hornblende gabbros.

Colour index: 35

Photo: fresh surface

154

Table A1- 7. Selected intrusive lithological types from Gold River area (NTS 092E/16) - tonalite varieties.

TONALITE VARIETIES

HORNBLENDE DIORITE

Fine- to coarse-grained variety: Creamy-grey weathering, white fresh,

idiomorphic, equigranular, nonmagnetic, phaneritic rock with interlocking

50-80 % 2-5 mm white feldspar and 15-50% colourless-light grey quartz,

0-10% 1 mm, platy biotite (partially or completely altered to chlorite) and/or

0-30% 1-3 mm prismatic green hornblende. Feldspars are intergrown with

quartz and show rare graphic texture. Feldspars are commonly included in

quartz. Also present are minor 0.5 mm euhedral magnetites.

Colour index: 10


TRONDHJEMITE

Medium- to coarse-grained variety: Rusty-light gray-white weathering, white-

gray fresh, hypidiomorphic, equigranular, nonmagnetic, phaneritic rock with

30-40% 3-4 mm light grey quartz, 40-50% 1-4 mm white feldspar, 0-10%

1-3 mm prismatic hornblende and 1mm, almost completely chloritized biotite,

always associated with hornblende.

Colour index: 0-10


155

Table A1- 8. Selected intrusive lithological types from Gold River area (NTS 092E/16) - mingling textures.

MINGLING HORNBLENDITE AND HORNBLENDE GABBRO VARIETIES

VERY COARSE-GRAINED HORNBLENDITE AND COARSE-GRAINED

HORNBLENDE GABBRO

Two alternating sheeted intrusions of hornblendite and hornblende gabbro

mingle at the contact zone due to induced flow. Commonly hornblende

megacrysts from the hornblendite are trapped in the gabbro; plagioclase

crystals from the gabbro are trapped in the hornblendite.

Photo: fresh surface; white arrow points to hornblendite; grey arrow points to the

gabbro

MEDIUM-GRAINED HORNBLENDITE WITH HORNBLENDE MEGACRYSTS

AND MEDIUM-GRAINED HORNBLENDE GABBRO

Two alternating sheeted intrusions of hornblendite and hornblende gabbro

mingle at the contact zone due to induced flow. A chunk of hornblendite

containing hornblende megacrysts is trapped in the gabbro and it is difficult to

distinguish the two units or define the contact between them.

Photo: polished surface; white arrows point to hornblende megacrysts; grey arrows

point to the gabbro

156


MINGLING HORNBLENDITE, HORNBLENDE GABBRO AND TONALITE VARIETIES

MEDIUM-GRAINED TONALITE AND MEDIUM-GRAINED HORNBLENDE

GABBRO

Two alternating sheeted intrusions of tonalite and hornblende gabbro mingle at

the contact zone due to induced flow. Plagioclase from the tonalite is randomly

distributed in the hornblende gabbro.

Photo: polished surface; white arrows point to plagioclase from the tonalite; white

dashed arrows point to gabbro; grey arrows points to contact between the hornblende

gabbro and the tonalite

MEDIUM-GRAINED TONALITE AND MEDIUM-GRAINED HORNBLENDE

GABBRO

Two intrusions: tonalite and hornblende gabbro mingle at the contact zone due

to induced flow. Spotted hornblende textures are generated by thorough

mingling of two magmas with an initial temperature gradient. Often, the spotted

hornblende texture grades into acicular hornblende texture or both grade into

tonalite.

Photo: polished surface; white arrow points to spotted hornblende; white dashed arrow

(left centre) points to the gabbro; grey arrows point to the tonalite.

157

Table A1- 9. Selected intrusive lithological types from Gold River area (NTS 092E/16) - mingling and mixing textures.

MINGLING AND MIXING HORNBLENDITE, HORNBLENDE GABBRO/ HORNBLENDE DIORITE AND TONALITE

VARIETIES

MEDIUM-GRAINED TRONDHJEMITE AND TONALITE AND MEDIUM-

GRAINED HORNBLENDE GABBRO

Trondhjemite and tonalite intrusions mingle after trondhjemite has been

emplaced into tonalite at the contact with the hornblende gabbro sheet. Induced

flow incorporates chunks of partly solid hornblende gabbro into the tonalite and

trondhjemite flowing mass and smears them, forming dark streaks and wisps.

Photo: polished surface; white arrow points to ghosty relict of the hornblende gabbro ;

grey arrow points to trondhjemite; white dashed arrow points to the tonalite.

HYBRIDIZED DIORITE

Fine- to medium-grained variety: Light grey weathering, medium grey fresh,

non-magnetic, phaneritic rock consisting of 30% two mm anhedral grey quartz,

55% two mm euhedral, white and grey feldspars and 10-15% 1-3 mm,

euhedral, black hornblendes. It can contain 2-5% 5 mm plagioclase

phenocrysts and/or glomerocrysts. A working name: hybridized diorite was

assigned to this variety that does not look like a hornblende gabbro/diorite, or a

tonalite. It is likely that magma mixing occurred prior to any further

crystallization and emplacement of this hybridized magma.

Photo: fresh surface; white arrow points to hornblende; grey arrow points to plagioclase

xenocryst; circle encloses grey plagioclase and quartz.

158


MINGLING HORNBLENDITE, HORNBLENDE GABBRO/ HORNBLENDE DIORITE AND TONALITE

VARIETIES

FINE-GRAINED HORNBLENDE GABBRO AND MEDIUM-GRAINED

ACICULAR HORNBLENDE DIORITE

Fine-grained hornblende gabbro contains irregular pockets of medium-grained

acicular hornblende diorite. It is likely that a certain degree of mingling occurred

between these two magmas, during which chunks of acicular hornblende diorite

became incorporated into a fine-grained diorite. Due to the fine-grained texture

in the hornblende gabbro, it is likely that mingling was due to immediate

injection of a hornblende gabbro magma causing disruption of partly solid

acicular hornblende diorite.

Photo: fresh surface; white arrow points to an acicular hornblende diorite pocket; grey

arrow points to a fine-grained hornblende gabbro.

FINE-GRAINED ACICULAR HORNBLENDE DIORITE AND MEDIUM-

GRAINED ACICULAR HORNBLENDE DIORITE

Fine-grained acicular hornblende diorite enclaves formed while injected into a

cooler medium-grained acicular hornblende diorite that most likely developed its

texture due to the temperature gradient.

Photo: weathered surface; white arrow points to fine-grained acicular hornblende diorite;

grey arrow points to a medium-grained acicular hornblende diorite

159


MINGLING AND MIXING HORNBLENDITE, HORNBLENDE GABBRO/ DIORITE AND TONALITE

VARIETIES

HYBRIDIZED HORNBLENDE GABBRO

Medium- to fine-grained hornblende gabbro with a flow structure and plagioclase crystals

that are aligned with the direction of flow. It is likely that plagioclase crystals are

xenocrysts and have become entrained by the hornblende gabbro during its ascent from

the tonalitic magmas.

Photo: fresh surface; grey arrow points to hornblende gabbro; white arrows point to

plagioclase xenocrysts?

HYBRIDIZED HORNBLENDE DIORITE AND MEDIUM-GRAINED

HORNBLENDE DIORITE

Coarse-grained hybridized hornblende diorite displaying during- and after-

emplacement mingling with a medium-grained hornblende diorite.

Photo: fresh surface; grey arrow points to a medium-grained hornblende diorite; white

arrow points to a coarse-grained hybridized hornblende diorite.

160

Table A1- 10. Outcrops with layered intrusions: Features and structures.

161


162


163


164


165

Figure A1- 1. Outcrop traverses of the CRIC. Detail mapping of intrusive types, contacts, structures and textures. Outcrop traverses can be located on the enclosed map of the complex in

Chapter 2.

166

Figure A1- 2. Outcrop traverses of the CRIC. Detail mapping of intrusive types, contacts, structures and textures. Outcrop traverses can be located on the enclosed map of the complex in Chapter 2.

167

Figure A1- 3. Sketch of the CRIC layered intrusion including sample locations. Outcrop can be located on the enclosed map of the complex in Chapter 2.

168

Figure A1- 4. Detailed sketch of areas S1, S2, and S3 of the CRIC layered intrusion in Figure A1-3.

169

Figure A1- 5. A detailed sketch of areas S4, S5, and S6 of the CRIC layered intrusion in Figure A1-3.

170

Figure A1- 6. Sketch of the CRIC layered intrusion including locations of one sample. Outcrop can be located on the enclosed map of the complex in Chapter 2.

171

Figure A1- 7. Sketch of the CRIC layered intrusion including locations of samples. Outcrop can be located on the enclosed map of the complex in Chapter 2.

172

Figure A1- 8. A detailed sketch of a part of the CRIC intrusion in the close vicinity of the layered intrusions. Outcrop can be located on the enclosed map of the complex in Chapter 2.

173

Figure A1- 9. A detailed sketch of the CRIC intrusion in the close vicinity of a contact between hornblende gabbros/ hornblende diorite and tonalite. The outcrop face appears to exhibit faint layering. The outcrop can be located on the enclosed map of the complex in Chapter 2.

174

Figure A1- 10. Sketch of the CRIC layered intrusion including locations of samples. The outcrop can be located on the enclosed map of the complex in Chapter 2.

175


176

Figure A1- 12. A detail sketch from Figure A1-11 shows flow deformation structures in form of convolutions, swirls, schlierens, wisps, lenses of during and after emplacement mingled varieties of hornblende gabbros and hornblendites. Outcrop can be located on the enclosed map of the complex in Chapter 2.

177


178

Figure A1- 14. A detailed sketch from the middle portion of the CRIC outcrop from Figure A1-13.

179

Figure A1- 15. Outcrop traverses of the LCIC. Detail mapping of intrusive types, contacts, structures and textures. Outcrop traverses can be located on the enclosed map of the complex in Chapter 2.

180

Figure A1- 16. Outcrop traverses of the LCIC. Detail mapping of intrusive types, contacts, structures and textures. Outcrop traverses can be located on the enclosed map of the complex in Chapter 2.

181

Figure A1- 17. CRIC layered intrusions and flow structures. Dotted arrows indicate trace of flow foliation. A: Outcrop with alternating hornblende gabbroic (HG) and olivine hornblenditic (OH) sheets. Subparallel sheets, pinching sheets, and cognate xenoliths are evidence of magmatic flow (solid arrows). B: Olivine hornblendite exhibiting narrow recessive subparallel grooves (arrows) due to preferential erosion of hornblende megacrysts, likely aligned by magmatic flow within the unit. C: Convoluted tops of quartz-bearing hornblende gabbro (HG) sheets (arrows) overlain and underlain by olivine hornblendite (OH) indicate magmatic flow prior to consolidation of sheeted intrusions. D: Layering defined by spotted hornblende gabbro unit underlain by zone with increased abundance of hornblende spots, which, in turn, overlain by a zone with fewer hornblende spots (zones indicated by arrows). Textures likely indicate magmatic flow within the unit. E: Olivine hornblendite (OH) sheet with internal recessive subparallel zones (arrows) and underlain by medium-grained hornblende gabbro (HG) with preferentially aligned plagioclase crystals indicating magmatic flow within the sheets. F: Nodular structures (arrows) in hornblende gabbro/hornblende diorite are likely produced by magmatic flow and are associated with banding in the layered gabbro complex (Miller 1934). Hammer for scale in the central bottom part of the photo.

182

Figure A1- 18. Flow structures of the CRIC with dotted arrows indicating trace of flow foliation. A: Three hornblende gabbro (HG) sheets display convoluted tops (arrows) and smeared bottoms. They alternate with olivine hornblendite (OH) sheets. B: Another example of flowing hybridized diorite (HYB) exhibiting preferential alignment of biotite, hornblende and plagioclase crystals. It is in abrupt contact with tonalite (T) and trondhjemite (TR). C, D and E: Details of convoluted (swirled) tops, as well as convoluted and smeared bottoms of hornblende gabbro sheets (HG) mingled with olivine hornblendite (OH) from the layered outcrop shown in A. F: Detail of spotted hornblende gabbro displaying alignment of spotted hornblendes due to magmatic flow within the unit. Hornblende string (arrows) may indicate contact interface between two magmas, along which shearing occurred. Spotted hornblende gabbro is in an abrupt contact (double arrow crosses the contact) with hornblende gabbro showing rapid increase in hornblende spots that blend to form more homogeneous texture.

183

Figure A1- 19. Flow structures of the CRIC with dotted arrows indicating trace of flow foliation. A: A face of a boulder from the immediate vicinity of layered intrusions shows olivine hornblendite with recessive, narrow grooves in braided stream pattern producing positive relief features of lensoid shape. Pencil for scale (oval). B and C: Subparallely aligned, stretched mafic enclaves (MF) of hornblende diorites, hornblende gabbros and hornblendites in tonalite (T). D: Rounded mafic enclaves (MF) in tonalite (T) showing “pillow-like” structures with disrupted and smeared margins (arrows) within flowing tonalite. E: Tonalitic-trondhjemitic (T) sheet overlain and underlain by sheets of hornblendites (H) and hornblende gabbros (HG). Wisps of smeared tonalite within hornblende gabbro and smeared portions of hornblende gabbro in tonalite indicate flow prior to their consolidation. Scale card in the central bottom of the photo. F: Mafic enclaves (MF) of hornblendite in tonalite (T). Hornblendite as a mafic enclave (MF) in the left upper part of the photo shows abrupt contact with tonalite (T). Hornblendite (MF) on the right of the photo shows gradational contact with tonalite characterized by spotted (SH) and acicular hornblende gabbro textures. Dotted line approximately divides acicular hornblende from spotted hornblende textures. Margins of enclaves are irregular, crenulated and smeared.

184

Figure A1- 20. Magmatic enclaves of the CRIC. A: Mafic enclave (MF) of hornblende diorite displaying mingling textures with tonalite (T) showing entrainment of plagioclase xenocrysts and tonalitic xenoliths (arrows). B: Dispersed mafic enclaves (MF) of hornblendite in tonalite (T). C: Mafic enclave (MF) of hornblendite containing distinctive white plagioclase crystals, which can represent either phenocrysts formed prior to emplacement of the hornblenditic magma or xenocrysts from tonalitic magma entrained prior or during emplacement of mobile hornblenditic magma. The fine-grained texture of mafic enclave indicates rapid cooling after emplacement into cooler tonalite. Arrows point to disrupted margin of a mafic enclave, which was produced by the tonalite while still mobile and flowing after initial cooling of mafic magma. D: Detail of the flowing tonalite along the margin of a mafic enclave. Biotite and plagioclase crystals in tonalite show preferential alignment (indicated by the dotted arrow). E and F: Other examples of mafic enclaves (MF) in tonalite (T). Arrows point to characteristic cuspate and lobate margins of mafic enclave. Hammer for scale in the red triangle.

185

Figure A1- 21. Contacts in the CRIC. Single arrows indicate direction of grain size decrease. Double arrows indicate the extent of mingling zones. A: Hornblenditic (H) enclave chilling against hybridized diorite (HYB). B: Acicular hornblende dioritic enclave (AH) chilling against tonalite (T). C: Olivine hornblenditic enclave (OH) chilling against tonalite (T). D and E: Hornblenditic enclave (H) chilling and simultaneously thoroughly mingling with tonalite (T). Products of this interaction between hornblenditic and tonalitic magmas are acicular (AH) and spotted hornblende (SH) textures. Ongoing convection in the tonalite causes fragmentation of partly consolidated hornblendite with acicular and spotted hornblende margins and entrainment of fragmented hornblendite that also develops mingling textures along the contact with flowing tonalite. F: Mingling between hornblende gabbro (HG) and olivine hornblendite (OH).

186

APPENDIX 2: PETROGRAPHY

Table A2- 1. Detailed petrographic descriptions of intrusive varieties from Chapter 3-hornblendites.

187

Figure A2- 1. Photomicrographs of hornblendites. A: Olivine hornblendite-sharp contact between resorbed orthopyroxene (opx) and hornblende (hbl) on one side (dashed arrows), anthophyllite (ath) jigsaw rim separating these two minerals on the other side (cross-polarized light). B: Olivine hornblenditehornblende (hbl), confirmed by microprobe, contains olivine (ol) inclusions and is shown replacing pyroxene, displaying both amphibole (solid arrows) and pyroxene (dashed arrows) cleavages. The presence of pyroxene cleavage indicates replacement (cross-polarized light). C: Olivine hornblendite- detail of poikilitic brown hornblende (hbl) exhibiting internal structures (dashed arrows) that could be relicts of clinopyroxene (cpx and solid arrow) (cross-polarized light). D: Megacrystic hornblendite and tonalite-dislodged chlorite after hornblende (chl) with light brown reaction rim (arrows) separating it from quartz (qtz) of tonalite (plane polarized light). E: Megacrystic hornblendite and tonalite-dislodged idiomorphic brown green hornblendes (hbl and solid arrows) and heavily fractured colourless quartz (dashed arrow) (plane polarized light). F: Megacrystic hornblendite and tonalite-a close up of diamond shaped hornblendes (hbl) separated from quartz (qtz) by fibrous rim of hornblende composition based on energy dispersive spectra (cross-polarized light).

188

Table A2- 2. Detailed petrographic descriptions of intrusive varieties from Chapter 3-hornblendites and hornblende gabbros.

189

Table A2- 3. Detailed petrographic descriptions of intrusive varieties from Chapter 3-hornblende gabbros and hornblende diorites.

190

Figure A2- 2. Photomicrographs of hornblende gabbros and hornblende diorites. A: Hornblende gabbro-interstitial (dashed arrow), medium-grained hornblende (hbl) from plagioclase-hornblende groundmass showing chloritized core that is likely to be a relict pyroxene (solid arrow) (cross-polarized light). B: Hornblende gabbro-plagioclase phenocryst (pl) showing partly resorbed core (arrows) and albite twinning (cross-polarized light). C: Quartz hornblende gabbro-coarse-grained groundmass plagioclase (pl) with partly resorbed andesine-labradorite core (solid arrow) and bytownite rim intergrown graphically (dashed arrow) with light brown hornblende (hbl) (cross-polarized light). D: Quartz hornblende gabbro- plagioclase inclusions (pl and arrows) in poikilitic hornblende megacryst (hbl) range in size from 0.5-3 mm. Common to medium-grained plagioclase (pl) growing from groundmass into poikilitic hornblende: “subophitic” texture (cross-polarized light). E: Spotted hornblende diorite- Fine-grained variety with 2 mm euhedral hornblende (hbl) spots in a heavily altered plagioclase (pl) –hornblende (hbl and arrows)-magnetite (mag) groundmass (plane polarized light). F: Spotted hornblende diorite- a poikilitic hornblende spot with chloritized-iron oxidized patches in the core (chl and arrows). Included are also wormy, heavily altered plagioclase grains (pl). Spot attains interstitial nature in upper part of photograph (dashed arrow). Individual hornblende spots are in a sharp contact (dotted arrow) (plane polarized light).

191

Table A2- 4. Detailed petrographic descriptions of intrusive varieties from Chapter 3-hornblende diorites and tonalites.

192

Figure A2- 3. Photomicrographs of hornblende diorites and tonalites. A: Spotted hornblende diorite- a partly resorbed plagioclase phenocryst (pl) showing microfaults (solid arrows) with recrystallized quartz (dotted arrows) in microfractures of plagioclase. Graphic intergrowth of plagioclase and green hornblende (dashed arrow) (cross-polarized light). B: Acicular hornblende diorite- plagioclase (Pl) xenocryst/phenocryst consisting of three zones that contains tiny hornblende inclusions (Hbl incl) (plane polarized light). C: Acicular hornblende diorite- quartz clot with biotite inclusions from a tonalite (dotted outline) incorporated in the groundmass of mafic enclave (plane polarized light). D: Acicular hornblende diorite-a close up on abundant, long apatite needles (arrows) enclosed in groundmass plagioclase (pl). Hornblende (hbl) and magnetite (mag) are also groundmass constituents (plane polarized light). E: and F: Tonalite- a dislodged relict of ferromagnesian phase from hornblendite (solid arrow), completely replaced by chlorite, surrounded by heavily fractured quartz (qtz) and separated from quartz by brown material that forms a reaction rim (dotted arrows). Plagioclase (pl) is also heavily fractured (cross-polarized and plane light retrospectively).

193

APPENDIX 3: ELECTRON MICROPROBE DATA

The mineral chemistry of olivine, pyroxene, hornblende, plagioclase, mica

and oxides from a hornblenditic and hornblende gabbroic sheets collected by

CAMECA SX50 electron-probe microanalyzer at the University of British

Columbia, under the supervision of Dr. Mati Raudsepp of the Department of

Earth and Ocean Sciences. The microprobe data was obtained with the beam

current set on to 20.03A, acceleration voltage to 15.03 kV, take off angle to 40o,

tilt angle to 0o and azimuth angle to 0o and using olivine, clinopyroxene,

amphibole, mica and feldspar standards. Two to five grains of each mineral

phase in a single thin section were subjected to two to six point analyses per

grain with targeting homogeneous areas of cores and margins of grains. No REE

analyses were obtained in this procedure.

194

Table A3- 1. Representative microprobe analyses of olivine and pyroxene from hornblenditic and gabbroic sheets from the Conuma River locality (chrys=chrysolite; bronz=bronzite).

Sample 212A E1 JN1 Sample 212A JN1 JN3 JN3 212 C

Olivine chrys chrys chrys Pyroxene bronz bronz bronz diop diop

SiO2 38.8231 38.14387 38.65786 SiO2 54.58391 54.48216 54.62668 52.25746667 53.2717

TiO2 0.015314 0.025467 0.012758 TiO2 0.02567 0.01412 0.13374 0.323033333 0.0637

Al2O3 0.049086 0.01905 0.009733 Al2O3 1.90148 1.77992 0.81822 1.582 0.428775

Cr2O3 0.016041 0.0057 0.008025 Cr2O3 0.15066 0.12354 0.0099 0.291333333 0.0644

FeO 18.80474 20.27807 20.07595 FeO 12.20761 12.44132 13.22854 4.642066667 5.431125

MnO 0.303477 0.320417 0.352033 MnO 0.32153 0.30348 0.40676 0.156266667 0.214375

MgO 42.53182 41.6558 41.38872 MgO 30.493 30.26846 29.84092 16.0577 15.5505

CaO 0.014273 0.009783 0.017517 CaO 0.37459 0.43946 1.01746 24.1676 24.59525

Na2O 0.006968 0.017483 0.004925 Na2O 0.01951 0.00882 0.00694 0.086633333 0.1079

NiO 0.184936 0.111767 0.140633 NiO 0.05102 0.0017 0.03994 0.0355 0.005925

Total 100.7498 100.5874 100.6682 Total 100.129 99.86298 100.1291 99.5996 99.73365

Numbers of ions on the basis of 4 oxygens Numbers of ions on the basis of 6 oxygens

Si 0.987433 0.979648 0.989867 Si 1.936913 1.940189 1.952586 1.934582219 1.975430312

Al 0.001472 0.000577 0.000294 Al 0.063087 0.059811 0.03448 0.065417781 0.018744859

Sum Z site 2 2 1.987065 2 1.994175171

Al 0.01646 0.014916 0 0.003627323 0

Ti 0.000293 0.000492 0.000246 Ti 0.000685 0.000378 0.003595 0.008993766 0.001776479

Cr 0.000323 0.000116 0.000162 Cr 0.004226 0.003478 0.00028 0.008526298 0.001887915

Fe2+

0.4 0.43556 0.429923 Fe2+

0.362286 0.370537 0.395451 0.143722792 0.168434242

Mn 0.005335 0.005688 0.00623 Mn 0.007886 0.00747 0.010049 0.003998414 0.00549442

Mg 1.612178 1.59442 1.579438 Mg 1.612602 1.60643 1.589641 0.885939081 0.85939178

Ca 0.000389 0.000269 0.000481 Ca 0.014243 0.016769 0.038969 0.958664318 0.977261068

Na 0.000344 0.000871 0.000245 Na 0.001342 0.000609 0.000481 0.006218569 0.007758061

Ni 0.003783 0.002309 0.002896 Ni 0.001456 4.87E-05 0.001148 0.001057038 0.000176716

Sum X+Y site 2.021187 2.020635 2.039615 2.020747599 2.022180682

M' 4.021187 4.020635 4.02668 4.020747599 4.016355853

Fe3+

0.063225 0.061587 0.079509 0.061921615 0.048867741

Fe2+

0.299061 0.30895 0.315942 0.081801177 0.119566501

Atomic ratios Mg/(Mg+Fe2+

) 84.35598 83.87004 83.42021 91.54719708 87.78635376

Mg/(Mg+total Fe+Mn) 79.90918 78.32419 78.36103 Mg/(Mg+total Fe+Mn) 81.33061 80.95143 79.67563 85.70892125 83.16798398

Mg/(Mg+Fe2+

) 80.12104 78.54365 78.604 Mg 81.07069 80.57386 78.53722 44.55702919 42.86057121

Fe2+

19.87896 21.45635 21.396 Fe 18.21328 18.58506 19.5375 7.228330661 8.400345457

Ca 0.716032 0.841077 1.925277 48.21464015 48.73908333

Fo Fo80.1 Fo78.5 Fo78.6 En En81.3 En81 En79.7 Ca48.2Mg44.6Fe7.2 Ca48.7Mg42.9Fe8.4

195

Table A3- 2. Microprobe analyses of olivine and pyroxene from hornblenditic and gabbroic sheets from the Conuma River locality (Ol=olivine; Px=pyroxene; G hbl=green hornblende; B hbl=brown hornblende).

Sample 212A-1 212A-2 212A-3 212A-4 212A-5 212A-6 212A-7 212A-8 212A-11 212A-12 212A-15 212A-16 212A-19

Location Core Core Margin Margin Margin Margin Core Core Core Core Margin Margin Margin

Ol & Px chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite

SiO2 39.4942 38.6278 39.2636 38.661 39.3765 38.5279 39.0041 38.3312 39.5603 38.2923 39.142 38.3721 38.8977

TiO2 0.0172 0.0274 0.007 0.0052 0 0.0692 0.0288 0.0087 0 0.0284 0.0084 0.0293 0

Al2O3 0.0199 0.0206 0.0117 0.0252 0.0223 0.0066 0.0226 0 0.0155 0.0172 0.015 0.0177 0.0133

Cr2O3 0.0323 0 0.0222 0.0262 0.0222 0.0101 0.0121 0 0 0 0.0061 0 0.0302

FeO 18.446 18.58 18.4253 18.4311 18.4996 18.1848 18.6873 18.3607 18.2447 18.3659 18.7511 18.2755 19.5658

MnO 0.232 0.3286 0.3139 0.2752 0.2955 0.3372 0.3318 0.3419 0.3224 0.3971 0.3305 0.2821 0.3199

MgO 42.7138 42.6188 42.7408 42.7241 42.968 42.7842 42.6506 42.6686 43.2204 43.091 42.8543 42.886 41.8169

CaO 0.0284 0.0075 0.0133 0.015 0.0116 0.0498 0.0017 0.0069 0.0168 0.0156 0 0 0.0116

Na2O 0 0.0146 0.0117 0 0.0068 0 0.0049 0 0 0 0 0.0291 0

NiO 0.2256 0.1716 0.2324 0.222 0.2442 0.1666 0.1917 0.1817 0.2274 0.1683 0.1734 0.1397 0.1245

Total 101.2094 100.3969 101.0419 100.385 101.4467 100.1364 100.9356 99.8997 101.6075 100.3758 101.2808 100.0315 100.7799

Sample 212A-21 212A-32 212A-33 212A-36 212A-37 212A-39 212A-43 212A-45 212A-49 212A-13 212A-14 212A-17 212A-18

Location Margin Core Margin Margin Core Core Core Core Core Margin Margin Core Margin

Ol & Px chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite bronzite bronzite bronzite bronzite

SiO2 39.2908 38.301 38.925 38.1499 38.6609 38.6246 38.7637 39.1451 38.6966 55.1989 54.036 54.8448 54.8926

TiO2 0 0.0088 0.0242 0 0 0.0067 0.0319 0.0333 0.0024 0.0249 0.0119 0.0204 0.0015

Al2O3 0.0279 0.0068 0 0.0166 0.0024 0 0.1468 0.0248 0.647 2.0471 1.7469 2.0688 0.655

Cr2O3 0 0.0141 0 0.0504 0.01 0.0161 0 0.0504 0.0505 0.2158 0.2199 0.1681 0.0832

FeO 19.5053 19.4916 19.1895 18.6919 19.7367 19.6101 19.2717 19.0177 18.3719 12.4498 12.2216 12.1528 11.5934

MnO 0.3846 0.2933 0.2968 0.2518 0.2863 0.2749 0.2633 0.2419 0.2755 0.2943 0.2943 0.2757 0.386

MgO 42.0238 42.092 42.4852 42.5635 42.0192 42.2823 42.1719 42.0593 42.2653 30.6617 30.5764 30.4552 31.3026

CaO 0.0121 0.0312 0.0041 0.0087 0 0.0104 0.0468 0.0069 0.0156 0.3885 0.4178 0.5011 0.4511

Na2O 0.0108 0 0 0.0156 0.0138 0.002 0.0235 0.0186 0.0019 0 0.0169 0.045 0.0421

NiO 0.1966 0.1177 0.1582 0.2389 0.2067 0.2102 0.1261 0.1464 0.1987 0.0526 0.0559 0.0458 0.1017

Total 101.4519 100.3565 101.083 99.9873 100.936 101.0373 100.8457 100.7444 100.5254 101.3336 99.5976 100.5777 99.5092

Sample 212A-25 212A-26 212A-27 212A-34 212A-35 212A-40 212C-13 212C-14 212C-15 212C-16 212C-22 E2 E1-1

Location Core Core Core Margin Margin Core relict in Ghbl relict in Ghbl relict in Ghbl relict in Ghbl relict in Bhbl Core Core

Ol & Px bronzite bronzite bronzite bronzite bronzite bronzite diopside diopside diopside diopside diopside chrysolite chrysolite

SiO2 55.4516 53.5037 54.9408 53.936 54.779 54.2557 52.9952 53.9118 52.591 53.5888 50.3586 38.1926 37.9909

TiO2 0 0.0699 0.0741 0.0158 0.0271 0.0111 0.0308 0.0686 0.0618 0.0936 0.7424 0.0502 0.04

Al2O3 1.4169 2.4029 2.3492 2.1243 2.4378 1.7659 0.1458 0.5099 0.5415 0.5179 4.3457 0.0404 0.0397

Cr2O3 0.0476 0.137 0.1995 0.2385 0.0643 0.1327 0.0279 0.0537 0.0515 0.1245 0.3618 0.004 0

FeO 13.0408 11.97 11.8085 12.2298 12.3788 12.2306 5.4082 5.3402 5.5972 5.3789 5.574 20.0388 19.926

MnO 0.365 0.291 0.3097 0.3314 0.3737 0.2942 0.2242 0.1986 0.2156 0.2191 0.1076 0.2908 0.3061

MgO 30.4913 30.1762 30.3027 30.2682 30.2906 30.4051 15.461 15.7126 15.3508 15.6776 15.5961 41.7037 41.3867

CaO 0.0915 0.5879 0.6011 0.3484 0.1778 0.1807 25.0844 24.1444 24.8783 24.2739 21.933 0.0145 0.0122

Na2O 0.0198 0.0291 0.0112 0.0066 0.0019 0.0225 0.0723 0.1384 0.0946 0.1263 0.4495 0.0684 0.0095

NiO 0.0525 0.0068 0.0797 0.0271 0.022 0.0661 0 0 0 0.0237 0 0.0958 0.0942

Total 100.977 99.1745 100.6765 99.5261 100.553 99.3646 99.4498 100.0782 99.3823 100.0243 99.4687 100.4992 99.8053

196

Table A3-2 (Continued).

Sample E1-2 E1-12 E1-13 E1-14 JN1-2 JN1-3 JN1-4 JN1-9 JN1-10 JN1-28 JN1-29 JN1-31 JN1-32 JN1-33

Location Core Core Core Core Core Core Core Core Core Core Core Core Core Core

Ol & Px chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite

SiO2 38.1057 37.8954 38.6317 38.0469 38.9033 38.3142 38.7546 38.2855 39.3801 38.9275 38.1388 38.0919 38.9749 38.3076

TiO2 0.0063 0.0299 0.0264 0 0.0059 0.0327 0.0121 0.0353 0.0192 0 0.0133 0.0011 0 0.0143

Al2O3 0.0096 0.0162 0.0031 0.0053 0.0102 0.0066 0.0049 0.0089 0.0178 0 0.0099 0.0027 0.0115 0.027

Cr2O3 0.0141 0.0161 0 0 0 0.0261 0 0.004 0.0402 0 0 0.014 0 0.012

FeO 20.4472 20.5512 20.0972 20.608 19.4349 19.4023 19.9794 19.7782 19.721 20.0306 20.0968 20.3731 20.5316 20.6207

MnO 0.3712 0.3344 0.2775 0.3425 0.3365 0.3532 0.3579 0.343 0.3264 0.3413 0.3777 0.331 0.3477 0.3957

MgO 41.6889 41.8594 41.7241 41.572 41.8145 41.7344 41.5942 41.6146 41.5047 41.2822 41.1228 41.2156 41.5015 41.2499

CaO 0 0.0093 0.0064 0.0163 0.0139 0.0052 0.004 0.0462 0.0306 0.0202 0.0243 0.0115 0.0289 0.0029

Na2O 0.0122 0 0 0.0148 0 0.0216 0.003 0.0039 0.0177 0 0 0.002 0.001 0

NiO 0.1327 0.0958 0.1177 0.1344 0.158 0.1716 0.2001 0.153 0.158 0.1345 0.1479 0.1596 0.1176 0.1142

Total 100.7879 100.8077 100.8841 100.7402 100.6772 100.0679 100.9102 100.2726 101.2157 100.7363 99.9315 100.2025 101.5147 100.7443

Sample JN1-40 JN1-42 JN1-14 JN1-15 JN1-16 JN1-20 JN1-1 JN1-25 JN1-26 JN1-30 JN1-36 JN1-37 JN1-41 JN1-43

Location Core Core Core Core Core Core Core Core Core Margin Core Core Core Core

Ol & Px chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite chrysolite bronzite bronzite bronzite bronzite bronzite

SiO2 39.0608 38.7551 38.8793 38.0482 38.8642 38.7023 38.2605 38.6008 38.9344 55.6658 54.7008 53.5846 54.6776 53.782

TiO2 0 0.0192 0.0072 0 0.0138 0 0.0417 0.0004 0 0.0068 0 0.0202 0.0149 0.0287

Al2O3 0.0013 0.016 0 0.0135 0.0029 0.0011 0 0.0305 0.0246 1.2311 2.043 2.0318 1.5805 2.0132

Cr2O3 0 0 0.028 0 0.02 0.024 0.0121 0 0 0.0603 0.174 0.1863 0.0332 0.1639

FeO 20.211 20.7318 20.9067 21.1598 20.7954 21.2597 19.2083 19.5074 19.6319 12.2315 12.8562 12.8023 11.9992 12.3174

MnO 0.383 0.331 0.2976 0.3737 0.3658 0.3405 0.2867 0.3131 0.3182 0.2591 0.3008 0.3177 0.32 0.3198

MgO 41.2007 40.8295 41.2444 41.065 40.9136 40.5269 42.4206 42.1814 42.2105 30.7107 29.7928 29.8698 30.9133 30.0557

CaO 0 0.0225 0.0231 0 0.0144 0.0173 0.0006 0.0197 0.0243 0.5424 0.4709 0.4848 0.1551 0.5441

Na2O 0.0079 0.002 0 0 0 0.0399 0 0 0.002 0.0178 0 0.0009 0.0019 0.0235

NiO 0.0622 0.1109 0.1663 0.1511 0.1159 0.1259 0.1834 0.1311 0.1968 0 0.0085 0 0 0

Total 100.9269 100.818 101.5526 100.8113 101.106 101.0376 100.4139 100.7844 101.3427 100.7255 100.347 99.2984 99.6957 99.2483

Sample JN3-1 JN3-3 JN3-4 JN3-5 JN3-24 JN3-6 JN3-7 JN3-8 JN3-2 JN3-26 JN3-10 JN3-14 JN3-22

Location Core Core Core Core Margin Core Core Core Core Margin relict in Bhbl relict in Bhbl relict in Bhbl

Ol & Px bronzite bronzite bronzite bronzite bronzite bronzite bronzite bronzite bronzite bronzite diopside diopside diopside

SiO2 53.3084 52.8615 54.3498 52.9758 53.7115 54.8028 53.4706 55.0624 55.3405 54.4571 51.9714 53.4447 51.3563

TiO2 0.2198 0.2791 0.2687 0.2415 0.1298 0.1516 0.1569 0.1651 0.1425 0.0526 0.294 0.1983 0.4768

Al2O3 2.0823 2.0921 1.8512 2.1068 1.8429 0.9577 0.7876 0.8203 0.8408 0.6847 1.2876 0.9781 2.4803

Cr2O3 0.0476 0.0926 0.0351 0.0454 0.0372 0.0041 0.033 0 0.0021 0.0103 0.2042 0.1417 0.5281

FeO 12.7298 13.9483 13.5806 13.7595 13.2681 12.7986 14.066 13.0117 12.6182 13.6482 4.3973 4.693 4.8359

MnO 0.4372 0.4056 0.4132 0.3961 0.3544 0.3937 0.4431 0.4155 0.3466 0.4349 0.1215 0.1882 0.1591

MgO 29.3938 28.169 28.9799 28.5096 29.3108 30.1259 29.0952 29.9345 30.1852 29.8638 16.1992 16.5184 15.4555

CaO 1.1081 1.1442 1.1601 1.2988 1.0479 1.1117 1.119 1.0846 1.0658 0.7062 24.5838 23.4712 24.4478

Na2O 0.0065 0.0508 0.0245 0.0237 0.0211 0 0 0.0081 0.0266 0 0.0488 0.095 0.1161

NiO 0.0169 0.027 0.0744 0.0575 0 0.0169 0.0744 0.0356 0.0119 0.0609 0.0524 0.0473 0.0068

Total 99.3504 99.0702 100.7375 99.4147 99.7237 100.363 99.2458 100.5378 100.5802 99.9187 99.1602 99.7759 99.8627

197

Table A3- 3. Representative microprobe analyses of amphiboles from hornblenditic and gabbroic sheets from the Conuma River locality (mgnhast=magnesiohastingsite; mgnhbl=magnesiohornblende; tschermak=tschermakite; anth=anthophyllite).

Sample 212A G 212A B 212C G 212C B A3 G A3 B A4 G A4 B JN1 G JN1 B JN3 B E1 G 212A 212C

Amphibole mgnhast pargasite mgnhbl mgnhast pargasite mgnhbl pargasite pargasite pargasite pargasite tschermak mgnhast anth actinolite

SiO2 43.5848 43.193 46.57 44.6387 43.6147 46.519 43.8145 42.5845 43.4236 43.72883 43.24706 43.5404 56.86 52.84468

TiO2 0.1175 2.70105 0.9965 1.45764 0.1219 1.4396 1.1052 2.78222 0.23448 2.033459 2.48968 0.1271 0.028 0.3109

Al2O3 13.6681 11.5493 9.0312 10.6798 12.87 9.1765 11.3533 11.7236 13.6468 11.34731 11.26833 13.9829 1.19 3.432375

Cr2O3 0.15017 0.6386 0.1385 0.18279 0.2226 0.7273 0.14195 0.1214 0.19967 0.595327 0.27291 0.08735 0.008 0.1391

FeO 8.81575 7.7657 9.873 9.90053 9.8283 7.7047 10.2709 9.75592 8.75189 8.44883 10.34114 8.29591 11.93 8.564975

MnO 0.16584 0.14077 0.1774 0.16578 0.17723 0.1635 0.1213 0.1603 0.18201 0.131443 0.16029 0.15864 0.409 0.19085

MgO 16.8486 16.5611 16.141 15.5135 16.6221 18.187 15.8062 15.4406 16.7192 16.5542 14.8351 17.1496 26.11 18.61085

CaO 10.4306 11.2949 12.061 12.068 10.6165 10.443 11.4293 11.6627 10.5221 11.20932 11.61226 11.0471 1.225 12.31335

Na2O 3.12962 2.4428 1.2768 1.53387 2.05513 1.4894 1.8081 1.82602 3.03184 2.339357 1.51303 2.4694 0.309 0.50485

K2O 0.12361 0.43718 0.4411 0.52445 0.3145 0.2013 0.4964 0.51672 0.12741 0.467282 0.50708 0.11291 0 0.1221

F 0.03374 0.07227 0.0322 0.02999 0.01438 0 0.01845 0.02336 0.04235 0.027418 0.04067 0.05041 0.029 0.040825

Cl 0.1026 0.03587 0.0563 0.05329 0.09815 0.0777 0.03595 0.02692 0.09487 0.04498 0.06901 0.08525 0.006 0.034113

O = F 0.01421 0.03043 0.0136 0.01263 0.00605 0 0.00777 0.00984 0.01783 0.011544 0.0171242 0.02123 0.012 0.017189

O = Cl 0.02315 0.00809 0.0127 0.01202 0.02215 0.0175 0.00811 0.00607 0.02141 0.010149 0.0155704 0.01923 0.001 0.007697

Total 97.1336 96.7941 96.77 96.7237 96.5272 96.111 96.3856 96.6084 96.9369 96.90606 96.323865 97.0664 98.08 97.08408

Number normalized on the base of 23 oxygens

Si 6.23905 6.19178 6.6924 6.4954 6.38027 6.7383 6.45393 6.27175 6.30622 6.374665 6.1861311 6.19974 7.824 7.516305

Al IV

1.76095 1.80822 1.3076 1.5046 1.61973 1.2617 1.54607 1.72825 1.69378 1.625335 1.8138689 1.80026 0.176 0.483695

Ti 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Sum T site 8 8 8 8 8 8 8 8 8 8 8 8 8 8

Al VI

0.54568 0.14364 0.2224 0.32749 0.59986 0.3054 0.42551 0.30732 0.6427 0.324824 0.0863763 0.54702 0.017 0.091858

Ti 0.01265 0.2912 0.1077 0.15951 0.01341 0.1568 0.12243 0.30817 0.02561 0.222936 0.2678314 0.01361 0.003 0.033257

Cr 0.01699 0.07237 0.0157 0.02103 0.02574 0.0833 0.01653 0.01413 0.02292 0.068608 0.0308612 0.00983 9E-04 0.015641

Fe3+

0.59886 0 0.6892 0.35624 0 0 0 0 0 0 1.2371045 0.71642 0.134 0.148296

Mg 3.59443 3.53813 3.4569 3.36423 3.62388 3.9262 3.46989 3.38909 3.61859 3.596494 3.1625302 3.63928 4.845 3.945037

Fe2+

0.23139 0.93102 0.4974 0.7715 0.73711 0.5283 0.96563 0.98129 0.69018 0.787138 0 0.07384 0 0.765911

Mn 0 0.01395 0.0107 0 0 0 0 0 0 0 0.0158472 0 0 0

Sum C site 5 4.99031 5 5 5 5 5 5 5 5 4.8005509 5 5 5

Mg 0 0 0 0 0 0 0 0 0 0 0 0 0.51 0

Fe2+

0.22516 0 0 0.07709 0.46532 0.4051 0.29966 0.22037 0.37279 0.24292 0 0.19766 1.239 0.10463

Mn 0.01641 0 0.0069 0.01667 0.01792 0.0164 0.01235 0.01632 0.01827 0.013244 0 0.01561 0.039 0.018762

Ca 1.59989 1.73492 1.8572 1.88158 1.66411 1.6209 1.80393 1.84048 1.63734 1.750907 1.7798093 1.68547 0.181 1.876608

Na 0.15855 0.26508 0.1359 0.02465 0 0 0 0 0 0 0.2201907 0.10126 0.032 1.17E-15

Sum B site 2 2 2 2 2.14735 2.0423 2.11594 2.07717 2.0284 2.00707 2 2 2 2

Na 0.7101 0.4139 0.2199 0.40811 0.58292 0.4183 0.51641 0.52145 0.85372 0.66123 0.1994491 0.58051 0.05 0.13923

K 0.02257 0.07996 0.0809 0.09736 0.0587 0.0372 0.09329 0.09709 0.02361 0.086906 0.092538 0.02051 0 0.022156

Sum A site 0.73267 0.49386 0.3008 0.50547 0.64162 0.4555 0.6097 0.61854 0.87733 0.748136 0.2919872 0.60103 0.05 0.161386

Total 15.7327 15.4842 15.301 15.5055 15.789 15.498 15.7256 15.6957 15.9057 15.75521 15.092538 15.601 15.05 15.16139

F 0.01546 0.03276 0.0148 0.0139 0.00665 0 0.0086 0.01088 0.01945 0.012641 0.0189987 0.02304 0.013 0.018413

Cl 0.0252 0.00871 0.0139 0.01324 0.02433 0.0191 0.00897 0.00672 0.02335 0.011112 0.0172748 0.02088 0.001 0.008245

(Na+K)A 0.73267 0.49386 0.3008 0.50547 0.64162 0.4555 0.6097 0.61854 0.87733 0.748136 0.2919872 0.60103 0.05 0.183543

AlVI

0.54568 0.14364 0.2224 0.32749 0.59986 0.3054 0.42551 0.30732 0.6427 0.324824 0.0863763 0.54702 0.017 0.091858

AlT

2.30663 1.95185 1.53 1.83209 2.21958 1.5671 1.97158 2.03557 2.33647 1.950159 1.9002453 2.34728 0.193 0.575553

Mg /(Mg + Fe2+

) 0.8873 0.79168 0.7986 0.75086 0.73279 0.7382 0.77295 0.77736 1 0.930577 0.8625644 0.93058 0.812 0.819224

Mg/(Mg+total Fe+Mn) 0.88372 0.78922 0.8703 0.79542 0.74808 0.8052 0.73088 0.73563 0.76994 0.775141 0.9950141 0.92688 0.791 0.791757

Mg# - Mg /(Mg + Fe2+

) 88.7299 79.1679 79.857 75.0859 73.2789 73.824 77.2946 77.736 100 93.0577 86.256437 93.0577 81.21 81.92239

Mg# - Mg/(Mg+total Fe+Mn) 88.372 78.9216 87.034 79.542 74.8081 80.522 73.0883 73.5629 76.9941 77.51406 99.501407 92.6877 79.14 79.1757

198

Table A3- 4. Microprobe analyses of amphiboles from hornblenditic and gabbroic sheets from the Conuma River locality (mgnhast= magnesiohastingsite; mgnhbl=magnesiohornblende; tschermak=tschermakite; anth=anthophyllite; mgnadan=magnesioadanagaite; V=very coarse; M=medium-grained; F=fine-grained; G=green; B=brown; LG=light green).

Sample 212A-1 212A-4 212A-11 212A-12 212A-14 212A-15 212A-16 212A-19 212A-20 212A-21 212A-22 212A-8 212A-9 212A-10

Location VG margin VG core VG core VG margin VG margin VG margin VG margin VG margin VG core VG margin MG core VB margin VB margin VB margin

Amphibole mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast pargasite pargasite pargasite

SiO2 43.2311 44.1375 43.3549 43.113 43.3518 44.1586 43.8696 43.6135 43.6577 43.2077 43.5097 43.5069 43.2827 42.9396

TiO2 0.1157 0.098 0.0841 0.0701 0.0789 0.0805 0.1549 0.1685 0.104 0.1217 0.1541 2.3606 2.8469 2.401

Al2O3 14.0093 13.5926 13.3211 13.8488 13.8631 13.3677 13.1941 13.4163 13.5859 14.0128 13.8135 11.615 11.3898 11.7842

Cr2O3 0.0904 0.0883 0.3816 0.143 0.0568 0.0484 0.1116 0.1305 0.1116 0.0905 0.4321 0.5325 0.6842 0.8675

FeO 8.9596 8.802 9.6788 8.9901 8.9028 8.8066 8.4503 8.4997 8.7903 8.8504 8.3425 7.6989 7.8796 7.8654

MnO 0.1881 0.1356 0.1912 0.1508 0.1914 0.1696 0.1136 0.2136 0.234 0.1491 0.1357 0.1408 0.1306 0.1712

MgO 16.8044 17.0133 16.893 16.8355 16.7543 16.9828 16.872 17.0398 16.8402 16.717 16.5801 16.7669 16.5725 16.5405

CaO 10.4402 10.0541 9.8601 10.3683 10.3058 10.6184 10.401 10.6139 10.5216 10.2782 10.8217 11.1976 11.3527 11.2225

Na2O 3.2744 3.2326 2.9702 2.9125 3.1419 3.0704 3.3548 3.0606 3.2502 3.2383 3.459 2.6805 2.3358 2.8741

K2O 0.1146 0.0934 0.1292 0.136 0.1305 0.0878 0.1275 0.114 0.1385 0.1373 0.1176 0.3503 0.4417 0.3353

F 0.0978 0.0669 0 0.067 0 0.0465 0.0672 0.0156 0.0724 0.0052 0 0.0213 0.0858 0.1493

Cl 0.1406 0.0838 0.0948 0.0719 0.1185 0.1004 0.0956 0.1114 0.0933 0.1241 0.0829 0.0574 0.033 0.0534

Total 97.4662 97.3981 96.959 96.707 96.8958 97.5377 96.8122 96.9974 97.3997 96.9323 97.4489 96.9287 97.0353 97.204

Sample 212A-23 212A-27 212A-3 212A-2 212A-13 212A-17 212A-18 212A-26 212A-5 212A-6 212A-7 212A-24 212A-25 212C-1

Location MG margin VG core VG core VG margin VG core VG margin VG core VG core VB margin VB core VB margin Clear rim Clear rim LG rim

Amphibole mgnhast mgnhast tschermak mgnadan mgnadan mgnadan mgnadan mgnadan pargasite pargasite pargasite anth anth actinolite

SiO2 44.1971 43.1997 45.2711 42.731 42.7332 42.7103 42.64 42.8725 43.0631 42.9484 43.4172 56.6845 57.029 52.9668

TiO2 0.2052 0.0918 0.0671 0.124 0.0772 0.2171 0.3881 0.412 2.8421 2.9315 2.8242 0.0422 0.0139 0.2978

Al2O3 13.7365 13.923 12.2555 13.9712 13.9064 13.9804 14.1957 14.0379 11.4293 11.5292 11.5485 1.4729 0.9076 3.2584

Cr2O3 0.1518 0.1156 0.0295 0.1429 0.0589 0.5421 0.6397 0.7361 0.6482 0.6257 0.4735 0.0166 0 0.1688

FeO 8.4581 9.0735 8.5104 8.9419 8.9277 8.877 8.5149 8.8563 7.9388 7.5585 7.653 11.7609 12.0909 8.6254

MnO 0.1493 0.1339 0.1595 0.1592 0.1524 0.149 0.1677 0.1795 0.1153 0.1323 0.1544 0.4009 0.4174 0.1884

MgO 16.9237 16.7763 17.7772 16.7944 16.8581 16.3953 16.455 16.4561 16.3555 16.5423 16.5891 25.8123 26.4078 18.4341

CaO 10.9543 10.3607 10.3093 10.5225 10.4934 10.212 10.7404 10.8467 11.4017 11.3172 11.2779 1.785 0.6655 12.3323

Na2O 2.8427 2.8774 2.6698 3.3165 3.1063 3.3656 3.1897 3.0136 2.2056 2.3082 2.2526 0.3761 0.2409 0.5441

K2O 0.147 0.1335 0.1173 0.109 0.1182 0.145 0.112 0.1314 0.4925 0.4618 0.5415 0 0 0.0914

F 0 0 0.0415 0.0052 0 0.0568 0 0.0365 0.0161 0.0538 0.1073 0.0246 0.0342 0.0375

Cl 0.1027 0.1138 0.0982 0.1018 0.0932 0.1168 0.1127 0.1237 0.0188 0.022 0.0306 0.0016 0.0097 0.019

Total 97.8684 96.7992 97.3064 96.9196 96.525 96.7674 97.1559 97.7023 96.527 96.4309 96.8698 98.3776 97.8169 96.964

199

Table A3-4. (Continued).

Sample 212C-4 212C-7 212C-8 212C-14 212C-15 JN3-13 JN3-14 212C-11 212C-13 212C-9 212C-10 212C-17 212C-16 212C-18

Location LG rim LG rim LG rim LG rim LG rim LG rim LG rim FG core FG core VB core VB core VB core VB core VB core

Amphibole actinolite actinolite actinolite actinolite actinolite actinolite actinolite mgnhbl mgnhbl mgnhast mgnhast mgnhast mgnhast mgnhast

SiO2 52.7736 53.1939 52.7949 52.8971 52.8283 53.0301 52.2727 50.7783 50.7277 45.8907 44.839 44.7424 43.7064 42.749

TiO2 0.276 0.32 0.3618 0.2975 0.2813 0.3151 0.3377 0.3184 0.3242 1.4845 1.2323 1.6068 2.2491 2.6238

Al2O3 4.1004 3.16 3.2681 3.2529 3.2026 3.5967 3.6199 5.6502 5.3059 9.7418 10.928 10.5406 11.181 11.9606

Cr2O3 0.2767 0.0845 0.1395 0.1224 0.0423 0.1436 0.135 0.0653 0.0926 0.1575 0.0839 0.2168 0.1389 0.2223

FeO 8.5351 8.4812 8.1772 8.6548 8.4327 8.6391 8.9743 9.2288 9.2257 9.7369 10.0661 8.9275 8.8659 9.8312

MnO 0.2055 0.1988 0.1971 0.2276 0.1614 0.1766 0.1714 0.1323 0.2339 0.1691 0.12 0.1642 0.1167 0.2179

MgO 18.4895 18.5033 18.8612 18.4745 18.8494 18.4964 18.7784 17.6149 17.8273 15.6702 15.3999 16.0878 16.2992 15.2015

CaO 12.2847 12.2971 12.5578 12.351 12.3331 12.1267 12.2241 12.1986 12.2213 11.9965 12.1101 12.2446 11.9541 11.9011

Na2O 0.5223 0.4304 0.4089 0.5338 0.4581 0.5822 0.559 0.8328 0.7181 1.3642 1.5704 1.4587 1.859 1.7727

K2O 0.1767 0.1463 0.1596 0.0664 0.111 0.1164 0.109 0.2173 0.2262 0.441 0.6085 0.4283 0.5561 0.582

F 0.0054 0.0589 0.0806 0.0054 0 0.1388 0 0.0053 0.0319 0 0 0.032 0.0213 0.0903

Cl 0.0435 0.0285 0.0182 0.0474 0.0475 0.0372 0.0316 0.0576 0.0426 0.0291 0.0753 0.0306 0.0659 0.0313

Total 97.6894 96.9029 97.0249 96.9308 96.7477 97.3989 97.2131 97.0998 96.9774 96.6815 97.0335 96.4803 97.0136 97.1837

Sample 212C-19 212C-2 212C-3 212C-5 212C-6 JN3-15 JN3-16 212C-12 A3-1 A3-2 A3-3 A3-5 A4-2 A4-5

Location VB core FG core FG core VB core VB core FG core FG core FG core MG core MG core MG core MB core VB core VB core

Amphibole mgnhast mgnhbl mgnhbl mgnhbl mgnhbl mgnhbl mgnhbl mgnhbl pargasite pargasite pargasite mgnhbl pargasite pargasite

SiO2 42.5354 46.0046 45.4686 44.9922 45.1422 46.1236 46.8393 48.1828 43.6642 43.9153 43.4396 46.5187 42.5814 42.684

TiO2 2.6083 0.4218 0.4479 0.4729 0.5616 0.3738 0.3499 0.2881 0.1403 0.1727 0.0873 1.4396 2.7362 2.7009

Al2O3 11.5856 10.0149 10.9033 10.5787 10.8355 9.1481 8.8813 7.6384 11.9427 12.22 13.6586 9.1765 11.6515 11.5973

Cr2O3 0.1301 0.2972 0.2822 0.1215 0.1446 0.2529 0.2928 0.065 0.36 0.3918 0.0693 0.7273 0.1832 0.2341

FeO 9.7104 10.6379 10.8878 10.1453 10.2737 11.0471 10.9418 10.436 9.6393 9.5751 10.0494 7.7047 9.9615 9.6225

MnO 0.1672 0.1469 0.1552 0.2653 0.1453 0.1721 0.1891 0.2063 0.185 0.1817 0.1711 0.1635 0.1264 0.1743

MgO 15.4673 14.8078 14.2574 15.754 15.673 15.2501 15.2485 16.4449 16.7153 16.7256 16.5237 18.187 15.0825 15.7329

CaO 11.7611 12.2034 12.5864 11.962 11.9712 12.1629 12.4025 11.8932 11.0066 11.0405 10.2095 10.4432 11.6524 11.7143

Na2O 1.7965 1.2117 1.1915 1.569 1.5695 1.2247 1.2003 1.0069 1.8818 1.8249 2.2569 1.4894 1.7589 1.7405

K2O 0.5461 0.5208 0.5223 0.5589 0.5637 0.4734 0.477 0.4104 0.5236 0.5206 0.1069 0.2013 0.5151 0.5244

F 0.0424 0.1312 0 0 0.021 0 0.0157 0.0524 0.0418 0.0157 0 0 0.0107 0

Cl 0.0344 0.0557 0.0721 0.0738 0.0574 0.1067 0.0604 0.0716 0.0775 0.0459 0.1346 0.0777 0.0181 0.0244

Total 96.3848 96.4539 96.7747 96.4936 96.9587 96.3354 96.8986 96.696 96.1781 96.6298 96.7069 96.1289 96.2779 96.7496

200


Sample A4-6 A4-7 A4-9 A4-4 A4-3 E1-1 E1-2 E1-8 E1-6 E1-7 E1-9 E1-10 E1-13 E1-3

Location VB core VB core VB core VG core VG core MG core MG core MG core MG margin MG margin VG core VG margin VG core Clear rim

Amphibole pargasite pargasite pargasite pargasite pargasite mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast mgnhast anth

SiO2 42.8115 42.284 42.5615 43.7821 43.8469 43.4024 43.3325 43.5304 43.2375 43.5893 43.6993 43.9747 43.5573 56.191

TiO2 2.7929 2.7431 2.938 1.5382 0.6722 0.1411 0.1204 0.1281 0.1103 0.1337 0.1222 0.1293 0.1317 0.0339

Al2O3 11.9606 11.852 11.5567 11.2099 11.4966 13.8562 13.881 14.0846 13.8758 14.0838 14.0872 13.892 14.1025 1.1958

Cr2O3 0.116 0.0632 0.0105 0.1179 0.166 0.0339 0.0466 0.1524 0.055 0.1335 0.0381 0.1228 0.1165 0.0229

FeO 9.6102 10.1054 9.48 10.1258 10.416 8.4234 8.3886 8.3973 8.3937 7.9923 8.4829 8.3056 7.9835 12.3568

MnO 0.1539 0.1896 0.1573 0.1145 0.1281 0.18 0.1183 0.1869 0.1955 0.1665 0.1783 0.1441 0.0995 0.4081

MgO 15.417 15.4587 15.5119 15.8017 15.8107 16.8133 17.0069 17.4962 17.1963 17.2792 17.4213 16.9897 16.9936 26.1563

CaO 11.5067 11.8017 11.6385 11.3742 11.4844 11.1085 10.878 11.2141 10.9199 11.2105 10.8146 11.0014 11.2294 0.9335

Na2O 1.8098 2.0274 1.7935 1.8156 1.8006 2.7509 2.415 2.2791 2.5727 2.2544 2.463 2.6356 2.3845 0.2238

K2O 0.5017 0.5064 0.536 0.4912 0.5016 0.1299 0.116 0.0805 0.1123 0.1331 0.1075 0.1148 0.1092 0

F 0 0.1008 0.0053 0.0369 0 0.0262 0.1724 0.0315 0 0.0474 0 0.0995 0.0263 0.0294

Cl 0.0339 0.0362 0.022 0.0182 0.0537 0.0882 0.0874 0.0834 0.0676 0.0843 0.0803 0.1034 0.0874 0.0032

Total 96.7142 97.1685 96.2112 96.4262 96.3768 96.954 96.5631 97.6645 96.7366 97.108 97.4947 97.5129 96.8214 97.5547

Sample E1-4 E1-5 E1-12 JN1-1 C JN1-2 C JN1-3 M JN1-4 M JN1-5 M JN1-6 M JN1-7 M JN1-8 M JN1-9 M JN1-10 M JN1-11 M

Location Clear rim Clear rim VG margin VB core VB core VB margin VB margin VB margin VB margin VB margin VB margin VB margin VB margin VB margin

Amphibole anth anth mgnhbl pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite

SiO2 56.1885 56.7111 52.1466 43.7205 43.5703 43.3106 43.1462 43.1185 43.6424 43.6502 43.5864 43.7788 43.3791 43.7676

TiO2 0.054 0 0.1028 1.7892 1.7539 1.8138 1.7765 1.8662 1.8321 1.7716 1.2366 1.2225 1.0539 1.7479

Al2O3 0.7949 0.6298 4.9214 11.3832 11.5195 11.5475 11.5664 11.7039 11.9893 11.5621 12.5522 11.9494 12.486 11.5814

Cr2O3 0 0.0166 0.3301 0.6497 0.5945 0.7574 0.6832 0.7522 0.528 0.6023 0.7844 0.761 0.555 0.7458

FeO 12.3354 12.2496 5.3583 8.3472 8.2908 8.1249 8.2769 8.523 7.9731 8.7243 8.3337 8.2736 8.9956 8.4677

MnO 0.4184 0.4356 0.1313 0.1034 0.1068 0.1102 0.1102 0.1152 0.1001 0.1406 0.2103 0.1593 0.1964 0.1406

MgO 26.5 26.5921 20.8767 16.6963 16.871 16.6788 16.3793 16.452 16.6383 16.9664 16.5575 16.7275 16.9095 16.6715

CaO 0.8179 0.68 12.1815 11.0042 11.3119 11.253 11.199 11.3812 11.098 11.1959 11.1107 10.9138 10.3814 11.4213

Na2O 0.1528 0.1535 1.0593 2.0749 2.119 2.329 2.1558 2.2146 2.5471 2.1881 2.7709 2.8328 3.0769 2.1851

K2O 0 0 0.0466 0.577 0.5611 0.4958 0.543 0.5619 0.4181 0.492 0.2997 0.3173 0.1527 0.542

F 0.0147 0.0882 0.0545 0 0 0.0106 0.0213 0 0.1326 0 0.0581 0 0 0

Cl 0.0057 0 0.0336 0.0417 0.0495 0.0699 0.0346 0.0581 0.0394 0.0346 0.0473 0.074 0.0646 0.0353

Total 97.2823 97.5565 97.2427 96.3873 96.7483 96.5015 95.8924 96.7468 96.9385 97.3281 97.5478 97.01 97.2511 97.3062

201



Location VB core VB core VG margin VG core VG core VG margin MG core MG core MG core MG core MG core VG core VG margin

Amphibole pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite pargasite

SiO2 44.0208 43.8635 43.5479 42.8355 43.7963 43.5162 43.1836 42.8376 43.5906 43.7295 43.2567 43.6471 43.7188

TiO2 2.4915 2.3943 0.5691 0.0457 0.1365 0.201 0.0897 0.153 0.1706 0.1506 0.2187 0.3748 0.4696

Al2O3 10.8598 10.922 13.3261 13.668 13.4822 14.1987 13.9891 13.5868 13.8834 13.7061 13.8464 13.3759 13.0518

Cr2O3 0.5421 0.4913 0.2801 0.3943 0.2125 0.185 0.0358 0.4567 0.1031 0.0716 0.2043 0.1455 0.1075

FeO 8.5056 8.5023 8.8145 9.52 8.8956 9.1007 8.561 8.6338 8.7782 8.5324 8.4938 8.4234 8.5174

MnO 0.0865 0.1678 0.1933 0.2386 0.2001 0.1321 0.173 0.1627 0.1848 0.1899 0.2764 0.1239 0.1273

MgO 16.4429 16.4015 16.6382 16.8294 16.6999 16.5484 16.9665 16.5963 16.5773 16.7911 16.6483 16.6978 16.9176

CaO 11.4771 11.1292 10.9216 9.9975 10.3218 10.3525 10.5125 10.7512 10.7735 10.1303 10.7813 10.5805 10.6201

Na2O 2.3053 2.235 2.9063 3.1187 3.0224 3.2166 2.9471 3.0437 3.3094 3.2144 3.1508 2.6581 2.7627

K2O 0.4759 0.4913 0.148 0.1426 0.1153 0.1512 0.1299 0.1157 0.1054 0.1227 0.1121 0.1226 0.136

F 0 0.0692 0.0937 0.0462 0.0414 0.0464 0.0103 0.1297 0.0104 0.0878 0 0 0

Cl 0.0377 0.0424 0.1049 0.0995 0.1107 0.1066 0.0972 0.0987 0.0845 0.0957 0.0727 0.0925 0.0806

Total 97.2452 96.7098 97.5437 96.936 97.0347 97.7554 96.6957 96.5659 97.5712 96.8221 97.0615 96.2421 96.5094


Location Clear rim Clear rim Clear rim VB core VB core VB core VB core VB core VB core VB core VB core VB core VB core

Amphibole anth anth anth tschermak tschermak tschermak tschermak tschermak tschermak tschermak tschermak tschermak tschermak

SiO2 56.5279 57.1641 54.9812 42.3518 42.7319 43.169 42.9407 42.9999 43.8263 43.5976 43.5454 43.4063 43.9017

TiO2 0.0296 0.0215 0.0822 2.9845 2.9228 3.0596 2.7028 2.9124 2.2273 2.1198 2.0989 2.0016 1.8671

Al2O3 0.6764 0.5479 2.32 11.6442 11.5908 11.4242 11.3424 11.3868 11.1543 11.0095 11.2906 11.1034 10.7371

Cr2O3 0.0559 0.0872 0.0644 0.0648 0.0839 0.1298 0.0731 0.0668 0.4314 0.3998 0.465 0.6055 0.409

FeO 12.4546 11.8626 12.0064 10.7447 9.8292 10.3913 10.7159 11.2818 10.2328 10.1514 10.1235 10.0484 9.8924

MnO 0.3885 0.4298 0.3855 0.1787 0.1081 0.1856 0.1719 0.1702 0.1857 0.1535 0.1739 0.1604 0.1149

MgO 26.0668 26.4275 24.8092 14.2685 14.998 14.7449 14.5305 14.3363 15.0804 15.1412 14.9631 15.044 15.2441

CaO 0.7555 0.6164 2.3822 11.5925 11.6898 11.6305 11.5159 11.4256 11.5926 11.4891 11.4354 11.7092 12.042

Na2O 0.1824 0.1115 0.611 1.4844 1.5433 1.5515 1.5012 1.4423 1.4996 1.5455 1.5421 1.5474 1.473

K2O 0.0012 0.005 0 0.5498 0.5067 0.5346 0.52 0.4854 0.4261 0.4943 0.5344 0.4955 0.524

F 0.0292 0 0.1525 0.1004 0 0 0 0.0894 0 0.0898 0.0529 0 0.0742

Cl 0 0.0105 0.0153 0.0594 0.0595 0.0133 0.0875 0.0773 0.0783 0.0806 0.0752 0.0822 0.0768

Total 97.168 97.284 97.8099 96.0237 96.064 96.8343 96.1019 96.6742 96.7348 96.2721 96.3004 96.2039 96.3563

202

Table A3- 5. Representative microprobe analyses of feldspars from hornblenditic and gabbroic sheets from the Conuma River locality (incl in hbl=inclusion of plagioclase in hornblende; gm=groundmass plagioclase; ppx=plagioclase phenocryst; andes=andesine; lab= labradorite; byt=bytownite; anor=anorthite).

Sample 212C 212C 212C 2 212C 3 A3 A4 A4 JN3 JN3 2 JN3 JN3 JN3

Location Gm & ppx Gm Gm core Gm core Incl in hbl Incl in hbl Gm Incl in hbl Ppx Ppx Ppx Ppx

Plagioclase andes/lab bytownite andesine andesine bytownite oligoclase oligoclase byt/anor bytownite andesine andes/lab andesine

SiO2 55.52695 46.1067 58.9452 56.47005 46.287667 61.64316 59.6167 45.408157 46.0161 56.781558 55.441967 58.1601

Al2O3 28.0167 34.4241 25.6746 27.29035 34.162433 24.07498 25.3723 34.684129 34.1387 27.2361 27.718667 26.4716

FeO 0.17665 0.2116 0.0443 0.1745 0.2294 0.0525 0.3181 0.2186 0.17765 0.1717667 0.1883333 0.1720667

MgO 0.007 0.0068 0.0073 0.00555 0.0018 0.00334 0.5233 0.0036143 0 0.0117083 0.0080667 0.0062333

CaO 10.3206 18.1372 6.8382 9.3422 17.846533 5.23344 4.3147 18.403329 17.5296 9.4058333 10.244167 8.5085

Na2O 5.687375 1.1759 7.5859 6.2505 1.3445333 8.43654 6.6727 1.1873571 1.45105 6.17825 5.7257333 6.6287667

K2O 0.073 0.0487 0.0506 0.0466 0.0304333 0.06434 2.4531 0.0111429 0.23915 0.0844667 0.0728 0.1102333

MnO 0.0096 0.0055 0.0244 0.01105 0.0060667 0.00236 0.015 0.0090714 0 0.002325 0.0010667 0.0095667

BaO 0.048775 0 0.0397 0.04285 0.0201 0.01216 0.0546 0.0069571 0.01935 0.0495667 0.065 0.0269333

Total 99.86665 100.1165 99.2102 99.63365 99.928967 99.52282 99.3405 99.932357 99.5716 99.921575 99.4658 100.094

Numbers of ions on the basis of 32 oxygens

Si 10.0160638 8.48501 10.59169 10.18175 8.5303181 10.993291 10.801653 8.3882303 8.5165043 10.206125 10.042059 10.402195

Al 5.95796318 7.468588 5.438864 5.800975 7.4222624 5.0616992 5.4196309 7.5536146 7.4487965 5.7714649 5.9189412 5.5817142

Sum Z site 15.974027 15.9536 16.03056 15.98273 15.95258 16.05499 16.221284 15.941845 15.965301 15.97759 15.961 15.983909

Fe 0.02664909 0.032567 0.006657 0.026313 0.0353565 0.0078303 0.0482016 0.0337724 0.0274974 0.0258207 0.028529 0.0257378

Mg 0.0018818 0.001865 0.001955 0.001491 0.0004944 0.0008877 0.1413041 0.000995 0 0.0031364 0.0021775 0.0016615

Ca 1.99476808 3.576455 1.316597 1.804877 3.5240982 1.0000559 0.8376587 3.6427305 3.4763041 1.811528 1.9881766 1.6305985

Na 1.98916928 0.41959 2.642961 2.185172 0.4804389 2.9172511 2.3441776 0.4252893 0.5207156 2.1532064 2.0108601 2.2987894

K 0.01679954 0.011434 0.0116 0.010719 0.0071553 0.0146388 0.5670467 0.0026261 0.0564681 0.0193696 0.0168227 0.0251532

Mn 0.00119687 0.0007 0.00303 0.001377 0.0007727 0.0002909 0.0018784 0.0011582 0 0.0002888 0.0001335 0.0011826

Ba 0.00344731 0 0.002795 0.003027 0.0014514 0.0008497 0.0038762 0.0005036 0.0014032 0.0034909 0.004613 0.0018875

Sum X site 4.03391197 4.042611 3.985595 4.032978 4.0497674 3.9418044 3.9441434 4.1070752 4.0823885 4.0168408 4.0513125 3.9850105

Mol %

Ab 49.7200723 10.47018 66.55391 54.74508 11.975964 74.193574 62.530028 10.44771 12.846111 54.044935 50.07297 58.13037

An 49.8600165 89.24451 33.15399 44.98637 87.845673 25.434122 22.344221 89.487776 85.760814 45.468893 49.508122 41.23357

Or 0.41991117 0.285317 0.2921 0.268554 0.1783623 0.372304 15.125751 0.0645136 1.3930746 0.4861716 0.4189077 0.6360598

203

Table A3- 6. Microprobe analyses of feldspars from hornblenditic and gabbroic sheets from the Conuma River locality (incl in hbl= inclusion of plagioclase in hornblende; gm=groundmass plagioclase; ppx=plagioclase phenocryst; c=core; andes=andesine; lab=labradorite; byt=bytownite; anor=anorthite; ppx 1-Z2=zone 2 in plagioclase phenocryst 1).

Sample 212C-41 212C-43 212C-45 212C-46 212C-49 212C-42 212C-47 212C-48 A3-1 A3-3

Location Gm & ppx c Gm & ppx c Gm & ppx c Gm & ppx c Gm Gm core Gm Gm Incl in hbl Incl in hbl

Plagioclase andes/lab andes/lab andes/lab andes/lab bytownite andesine andesine andesine bytownite bytownite

SiO2 55.1859 56.0829 56.208 54.631 46.1067 58.9452 56.8803 56.0598 46.254 46.3343

Al2O3 28.4437 27.7834 27.8386 28.0011 34.4241 25.6746 27.4673 27.1134 34.1522 34.079

FeO 0.1505 0.1624 0.1789 0.2148 0.2116 0.0443 0.1394 0.2096 0.2325 0.232

MgO 0 0 0.0211 0.0069 0.0068 0.0073 0 0.0111 0 0.002

CaO 10.8569 9.8288 10.2347 10.362 18.1372 6.8382 9.2958 9.3886 17.9942 17.6329

Na2O 5.3862 5.976 5.7189 5.6684 1.1759 7.5859 6.2208 6.2802 1.3603 1.473

K2O 0.0768 0.0559 0.0707 0.0886 0.0487 0.0506 0.0485 0.0447 0 0

MnO 0 0 0.0384 0 0.0055 0.0244 0 0.0221 0 0.0182

BaO 0.0348 0.0497 0.0559 0.0547 0 0.0397 0 0.0857 0 0.0427

Total 100.1348 99.9391 100.3652 99.0275 100.1165 99.2102 100.0521 99.2152 99.9932 99.8141

Sample A3-5 A4-1 A4-2 A4-3 A4-5 A4-6 A4-7 JN3-16 JN3-17 JN3-18

Location Incl in hbl Incl in hbl Incl in hbl Gm Gm Incl in hbl Incl in hbl Ppx 1-Z4 & Ppx 2-Z1 Incl in hbl Incl in hbl

Plagioclase bytownite oligoclase oligoclase oligoclase oligoclase oligoclase oligoclase bytownite byt/anor bytownite

SiO2 46.2747 61.5604 60.9068 62.256 62.0003 61.4923 59.6167 45.108 45.8 44.714

Al2O3 34.2561 24.0629 24.3149 23.6872 24.1754 24.1345 25.3723 34.5864 34.6774 34.825

FeO 0.2237 0.0241 0.0765 0.0565 0.0671 0.0383 0.3181 0.2032 0.2109 0.245

MgO 0.0034 0.0163 0 0.0004 0 0 0.5233 0 0 0.0047

CaO 17.9125 5.3093 5.5636 4.8644 5.2193 5.2106 4.3147 18.0759 18.4353 18.3337

Na2O 1.2003 8.394 8.1386 8.6937 8.4682 8.4882 6.6727 1.3091 1.1437 1.1723

K2O 0.0913 0.071 0.0603 0.0604 0.0584 0.0716 2.4531 0.0341 0 0

MnO 0 0 0 0.0118 0 0 0.015 0.0435 0 0.0082

BaO 0.0176 0 0.0211 0.0174 0.0012 0.0211 0.0546 0 0.005 0.0287

Total 99.9796 99.438 99.0818 99.6478 99.9899 99.4566 99.3405 99.3602 100.2723 99.3316

Sample JN3-19 JN3-20 JN3-33 JN3-35 JN3-3 JN3-34 JN3-21 JN3-23 JN3-28 JN3-40

Location Incl in hbl Incl in hbl Ppx 1-Z4 & Ppx 2-Z1 Ppx 1-Z4 & Ppx 2-Z1 Ppx 2-Z3 Ppx 2-Z3 Ppx 1-Z1 Ppx 1-Z1 Ppx 1-Z1 Ppx 1-Z6

Plagioclase byt/anor byt/anor bytownite byt/anor bytownite bytownite QUARTZ QUARTZ QUARTZ QUARTZ

SiO2 45.5239 44.6834 46.4007 45.6271 46.4301 45.6021 100.2785 101.8581 99.0466 99.4073

Al2O3 34.8515 34.8838 34.28 34.6848 34.1783 34.0991 0.6501 0.0928 0 0.0264

FeO 0.1885 0.2114 0.2409 0.2303 0.1184 0.2369 0 0.0203 0.037 0.006

MgO 0 0.0057 0.0132 0.0017 0 0 0.0119 0.002 0.0159 0.0183

CaO 18.6875 18.7343 18.0432 18.5134 17.186 17.8732 0.0006 0.014 0.003 0.003

Na2O 1.0232 1.1314 1.3931 1.1387 1.4893 1.4128 0.0091 0.0144 0 0.0045

K2O 0 0 0.025 0.0189 0.449 0.0293 0.0173 0.0193 0 0

MnO 0.0008 0 0.011 0 0 0 0 0.033 0 0

BaO 0.015 0 0 0 0.0175 0.0212 0.0524 0.0175 0.025 0

Total 100.2904 99.65 100.4071 100.2149 99.8686 99.2746 101.0199 102.0714 99.1275 99.4655

204


Sample JN3-39 JN3-8 JN3-12 JN3-15-PPX-Z2 JN3-24 JN3-25 JN3-26 JN3-27 JN3-24 JN3-25

Location Ppx 1-Z6 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2

Plagioclase QUARTZ andesine andesine andes/lab andesine andes/lab andesine andesine andesine andes/lab

SiO2 101.3425 56.0811 56.6264 56.2152 56.8931 56.7238 56.9022 57.3688 56.8931 56.7238

Al2O3 0.0148 27.2924 26.9982 27.9487 26.935 27.4071 27.1052 27.2294 26.935 27.4071

FeO 0.009 0.1092 0.1104 0.1647 0.1742 0.1724 0.2173 0.1836 0.1742 0.1724

MgO 0.0027 0.0042 0.0049 0.0142 0.0347 0.0045 0.0094 0.01 0.0347 0.0045

CaO 0 9.2506 9.141 9.8549 9.0424 9.9487 9.3359 9.2984 9.0424 9.9487

Na2O 0 6.4224 6.363 5.7784 6.3757 5.919 6.1886 6.1871 6.3757 5.919

K2O 0.0071 0.0342 0.051 0.0435 0.0976 0.0801 0.0932 0.1386 0.0976 0.0801

MnO 0.0099 0.0003 0.0009 0.0013 0 0.0127 0 0 0 0.0127

BaO 0.0187 0.0646 0.0186 0.0112 0.0956 0.0646 0.0484 0.041 0.0956 0.0646

Total 101.4047 99.259 99.3144 100.0321 99.6483 100.3329 99.9002 100.4569 99.6483 100.3329

Sample JN3-26 JN3-27 JN3-29 JN3-6 JN3-37 JN3-38 JN3-7 JN3-31 JN3-36

Location Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 1-Z2 & Ppx 2-Z2 Ppx 2-Z4 Ppx 2-Z4 Ppx 2-Z4 Ppx 1-Z3 & Z5 Ppx 1-Z3 & Z5 Ppx 1-Z3 & Z5

Plagioclase andesine andesine andesine andes/lab andes/lab andes/lab andesine andesine andesine

SiO2 56.9022 57.3688 56.6802 55.1578 56.3007 54.8674 58.5986 58.0665 57.8152

Al2O3 27.1052 27.2294 27.2405 27.7384 27.4572 27.9604 26.7431 26.514 26.1577

FeO 0.2173 0.1836 0.1819 0.1299 0.2302 0.2049 0.0992 0.2262 0.1908

MgO 0.0094 0.01 0 0.0028 0.0107 0.0107 0 0.0052 0.0135

CaO 9.3359 9.2984 9.3727 10.1621 10.0492 10.5212 8.623 8.633 8.2695

Na2O 6.1886 6.1871 6.2344 5.8001 5.6478 5.7293 6.5257 6.7853 6.5753

K2O 0.0932 0.1386 0.0659 0.0645 0.0993 0.0546 0.0754 0.1251 0.1302

MnO 0 0 0 0.0032 0 0 0 0.0248 0.0039

BaO 0.0484 0.041 0.0012 0.0621 0.1118 0.0211 0.0137 0.0348 0.0323

Total 99.9002 100.4569 99.7768 99.1209 99.9069 99.3696 100.6787 100.4149 99.1884

205

Table A3- 7. Representative microprobe analyses of mica and oxides from hornblenditic and gabbroic sheets from the Conuma River locality (phlo=phlogopite; herc=hercynite; ilm=ilmenite).

Sample 212A E1 JN1 JN3

Label phlo phlo phlo phlo

SiO2 39.391925 39.69666 38.900363 38.820533

TiO2 0.600225 0.63406 0.8721625 2.2680667

Al2O3 16.710625 16.38768 16.481475 16.007667

Cr2O3 0.494025 0.54178 0.5322125 0.0591333

FeO 5.741725 5.92728 6.069725 9.6103

MnO 0.04205 0.05064 0.0484125 0.0375

MgO 23.38355 22.81576 22.910563 19.8797

CaO 0.041675 0.05484 0.00975 0.0193

Na2O 1.82375 2.0241 1.1538375 0.7608333

K2O 6.9817 6.67744 8.01565 7.9411333

F 0.029 0.07144 0.0344625 0.0905333

Cl 0.051125 0.05442 0.056375 0.0839333

F=O 0.0122105 0.03008 0.0145105 0.0381193

Cl=O 0.0115351 0.0122785 0.0127196 0.0189375

Total 95.267629 94.893741 95.057757 95.521577

Numbers of ions on the basis of 22 oxygens

Si 5.5602921 5.6197127 5.5396449 5.5762341

Al 2.4397079 2.3802873 2.4603551 2.4237659

Sum Z site 8 8 8 8

Al 0.341098 0.3547622 0.3066625 0.2870193

Ti 0.0637177 0.0675066 0.0934074 0.2450139

Cr 0.0551278 0.0606338 0.0599163 0.006715

Fe 0.6778104 0.7017639 0.7228908 1.1544945

Mn 0.0041024 0.0049549 0.0047651 0.003723

Mg 4.9190647 4.813675 4.8623443 4.2557

Sum Y site 6.0609209 6.0032963 6.0499863 5.9526657

Ca 0.0063032 0.0083186 0.0014877 0.0029705

Na 0.4991399 0.5555955 0.3185954 0.2119023

K 1.2572825 1.2060115 1.4562915 1.455269

Sum X site 1.7627257 1.7699256 1.7763747 1.6701418

F 0.012946 0.0319853 0.0155211 0.0411279

Cl 0.0122299 0.0130563 0.0136055 0.0204322

Mg/(Mg+Fe2+

) 87.889485 87.276373 86.9829 78.660758

Mg/(Mg+total Fe+Mn) 87.889485 87.276373 87.05711 78.660758

Sample 212A A3 JN3

Label herc herc ilm

SiO2 0.0271 0 0.04085

TiO2 0.01095 0.0334 51.0352

Al2O3 63.65565 60.0621 0

Cr2O3 0.09055 0.0458 0.02825

FeO 18.86455 25.4594 42.89965

MnO 0.12285 0.2152 4.33755

MgO 16.3614 12.97845 0.56

CaO 0.0692 0 0.1655

V2O3 0.02275 0.00975 0

NiO 0.3071 0.1817 0.0094

Total 99.5321 98.9858 99.0764

Numbers of ions on the basis 32 (herc) and 6 (ilm) oxygens

Si 0.0056556 0 0.002098921

Ti 0.0017186 0.0054585 1.972101172

Al 15.661431 15.38729 0

Cr 0.0149392 0.0078681 0.001147503

Fe 3.2925229 4.6269803 1.843457484

Mn 0.01772 0.032322 0.154039112

Mg 5.0887259 4.2031856 0.042881864

Ca 0.0154742 0 0.009111631

V 0.0031368 0.0013998 0

Ni 0.0515478 0.0317579 0.000388468

Total 24.152872 24.296262 4.025226156

206

Table A3- 8. Microprobe analyses of mica and oxides from hornblenditic and gabbroic sheets from the Conuma River locality (phlo=phlogopite; herc=hercynite; ilm=ilmenite).

Sample 212A-2 212A-6 212A-7 212A-8 E1-1 E1-2 E1-3 E1-4 E1-5 JN1-1 JN1-2 JN1-3 JN1-4 JN1-5

Location core core core core core core core core core core core core core core

Mica phlo phlo phlo phlo phlo phlo phlo phlo phlo phlo phlo phlo phlo phloSiO2 39.0477 39.6454 39.3725 39.5021 39.7157 39.8051 39.4135 39.5911 39.9579 38.5604 38.8741 39.1962 38.881 38.7

TiO2 0.5608 0.4476 0.6341 0.7584 0.3447 0.3828 0.9579 0.7173 0.7676 0.9847 0.9671 0.8645 0.9887 1.0822

Al2O3 16.8067 16.531 16.8157 16.6891 16.1465 16.1094 16.9098 16.3433 16.4294 16.595 16.4387 16.4906 16.4317 15.9647

Cr2O3 0.4794 0.1799 0.6113 0.7055 0.571 0.5588 0.489 0.5195 0.5706 0.5989 0.6203 0.5221 0.389 0.447

FeO 5.712 5.341 6.0151 5.8988 5.9044 5.6491 6.114 5.8521 6.1168 5.8166 5.8367 5.7162 6.1278 6.8939

MnO 0 0.0172 0.0309 0.1201 0.0902 0 0.0173 0.0694 0.0763 0.0617 0 0.0721 0.0137 0.154

MgO 23.0823 24.0501 23.0793 23.3225 22.977 23.4881 22.279 22.7011 22.6336 22.6268 22.5197 22.5349 23.1233 23.0587

CaO 0.0576 0.042 0 0.0671 0.1124 0.0061 0.0543 0.0845 0.0169 0.03 0 0 0 0.0024Na2O 1.8778 1.699 1.8269 1.8913 1.7733 1.8679 2.0403 2.355 2.084 1.311 1.1899 1.3366 1.1636 0.8779

K2O 7.3253 6.9567 6.9947 6.6501 6.6589 7.2665 6.6591 6.061 6.7417 8.2698 8.1575 8.0133 7.8519 7.9096

F 0 0.0818 0.0342 0 0.0481 0.1237 0.1648 0.0137 0.0069 0.0759 0.0897 0.069 0 0.0205

Cl 0.0529 0.061 0.0465 0.0441 0.0428 0.067 0.0476 0.0655 0.0492 0.0455 0.0735 0.0488 0.064 0.0487

Total 95.0025 95.0527 95.4612 95.6491 94.385 95.3245 95.1466 94.3735 95.4509 94.9763 94.7672 94.8643 95.0347 95.1596

Sample JN1-6 JN1-7 JN1-8 JN3-3 JN3-4 JN3-5

Location core core core core core core

Mica phlo phlo phlo phlo phlo phlo Sample 212A-1 212A-2 A3-1 A3-2 JN3-1 JN3-3

SiO2 39.4657 39.2924 38.2331 38.4076 39.5267 38.5273 Location core core core core core core

TiO2 0.6591 0.5726 0.8584 2.2439 2.1353 2.425 Oxide herc herc herc herc ilm ilm

Al2O3 16.7477 16.6939 16.4895 15.9453 16.1626 15.9151 SiO2 0.0234 0.0308 0 0 0.0521 0.0296

Cr2O3 0.6709 0.6762 0.3333 0.0042 0.1395 0.0337 TiO2 0.0189 0.003 0.0244 0.0424 50.9306 51.1398

FeO 6.21 5.7098 6.2468 9.7589 9.2015 9.8705 Al2O3 63.2229 64.0884 59.6195 60.5047 0 0

MnO 0.0137 0.0721 0 0.0273 0.0682 0.017 Cr2O3 0.0279 0.1532 0.0213 0.0703 0.0263 0.0302

MgO 22.6449 22.599 24.1772 20.1085 19.9194 19.6112 FeO 18.6507 19.0784 26.4166 24.5022 46.0774 39.7219

CaO 0.0216 0.0096 0.0144 0.0272 0.026 0.0047 MnO 0.1378 0.1079 0.2498 0.1806 1.0216 7.6535

Na2O 1.2257 1.1126 1.0134 0.7498 0.8325 0.7002 MgO 16.2029 16.5199 12.4183 13.5386 0.9788 0.1412

K2O 8.2378 8.2607 7.4246 7.8137 7.9407 8.069 CaO 0.0601 0.0783 0 0 0.1671 0.1639

F 0.0069 0 0.0137 0.0474 0.1293 0.0949 V2O3 0.0401 0.0054 0.0195 0 0 0

Cl 0.0416 0.0528 0.0761 0.0676 0.0795 0.1047 NiO 0.3147 0.2995 0.1906 0.1728 0.0188 0

Total 95.9456 95.0517 94.8805 95.2014 96.1612 95.3733 Total 98.6994 100.365 98.96 99.0116 99.2727 98.8801

207

0

1

2

0 0.5 1

212A G

212A B

212C G

212C B

A3 G

A3 B

A4 G

A4 B

JN1 G

JN1 B

JN3 B

E1 G(Na+K) atoms

AlVI

Representative analyses of calcic hornblendes (diagram after Deer et a. 1966)

Pargasite

Hornblende

Tschermakite

Edenite

Tremolite

0

1

2

0 1 2

212A G

212A B

212C G

212C B

A3 G

A3 B

A4 G

A4 B

JN1 G

JN1 B

JN3 B

E1 G

Representative analyses of calcic hornblendes (diagram after Deer et al. 1966)

(AlVI + Fe 3+ + Ti) atoms

Pargasite Tschermakite

HornblendeEdenite

Tremolite

AlVI

Figure A3- 1. Hornblendes from olivine hornblendite and hornblende gabbro sheets. Fe

2+

and Fe3+

were calculated after Leake et al. (1997). Hornblende data plotted on the Deer et al. (1966) diagrams falls in the field between hornblende and pargasite. This is consistent with the plot for calcic hornblende after Leake et al. (1997).

208

APPENDIX 4: WHOLE ROCK GEOCHEMISTRY

Nineteen samples of Jurassic intrusions and one sample of Karmutsen

country rock from the Conuma River locality and six samples of Jurassic

intrusions and one sample of Karmutsen country rock from the Leagh Creek

locality were submitted for whole rock geochemistry analyses (Table 25-26).

Samples selected for whole rock geochemistry analyses were cleaned and had

the oxidation staining removed either by hammer or by a rock saw. About 50 g of

fresh sample was sent to the labs.

Samples obtained during 2007 fieldwork were sent to the lab: ALS

Chemex, North Vancouver, BC and analyzed for major oxides by XRF (X-ray

fluorescence) method and trace elements by ICP-MS (Inductively coupled

plasma-Mass spectrometry). Samples obtained during 2008 fieldwork were sent

to the Activation Laboratories Ltd, Ancaster, Ontario, where they were analyzed

for major oxides by FUS-ICP (Fusion-Inductively coupled plasma) and trace

elements by either FUS-ICP or by INAA (Instrumental neutron activation

analyses).

In ALS Chemex, samples were dried first either in the oven (max. 60oC) or

by air, depending on how wet they were. Samples are then crushed to reduce the

grain size in coarse-grained varieties. If more size fractions of samples are

required, splitters are used for that purpose. Then the samples are pulverized

(grinded) in grinding mills to a max. 75 micron mesh. A lithium metaborate fusion

209

of samples was applied prior to the XRF method was used to determine major

oxide concentrations in samples. ICP-MS was used to determine trace element

concentrations. Prior to that, samples were subjected to lithium borate fusion,

then they were dissolved in acids (http://www.alsglobal.com/Global/Home.aspx).

In Activation Laboratories Ltd, major oxide concentrations were obtained

by using Fusion-ICP method, in which the sample fused in a furnace with lithium

metaborate and lithium tetraborate. Melt obtained from furnace was dissolved in

5% nitric acid. Samples were analyzed in Thermo Jarrell-Ash ENVIRO II ICP or a

Spectro Cirros ICP machines. Ten samples (one batch) were analyzed together

with a method reagent blank, certified reference and 17% replicates and

calibrated using one of seven prepared USGS and CANMET certified reference

materials. Trace elements were analyzed by INAA, which involved ~30 g of a

sample being first encapsulated, weighed and irradiated with flux wires at a

therma neutron flux 7 x 1012 n cm-2 s-1. Seven days are allowed for a decay of

Na-24 and high purite Ge detector is used to count particles in sample. The

detector has a resolution better than 1.7 KeV for the 1332 KeV Co-60. One

standard per eleven samples is also run in analyses, but it is not used for

calibration, only for the accuracy of the analyses. Multiple certified international

reference materials are used for calibration of samples. 10-30% of samples are

checked again and remeasured (http://www.actlabs.com/methsub_code4b.htm).

CIPW norm and error analyses included together with whole rock

geochemistry data in this Appendix, were calculated using excel spread sheet

programs created and provided by Derek Thorkelson.

http://www.alsglobal.com/Global/Home.aspx

http://www.actlabs.com/methsub_code4b.htm

210

Table A4-1. Whole rock geochemistry analyses for intrusions from the Conuma River and Leagh Creek localities - major and minor oxides and CIPW norm. Abbreviations: hbl=hornblende, non-cum=non-cumulate. Note: FeO* calculated as FeO*=FeO+0.8998Fe2O3.

SAMPLE DM05-212A DM05-212C KF 07-A3 KF 07-A4 KF 07-B4 KF07-D4 KF07-D5 KF 07-E1 KF 07-F1 KF 07-JN1 KF 07-JN2 KF 07-JN2-2

Locality Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma

Rock type hornblendite hbl gabbro hornblendite hbl gabbro hornblendite trondhjemite hbl diorite hornblendite hbl gabbro hornblendite hornblendite hornblendite

Intrusion type sheet 1 sheet 2 sheet 3 sheet 4 sheet or stock stock chill mafic enclave sheet sheet or stock sheet sheet sheet

Texture cumulate cumulate cumulate cumulate cumulate non-cumulate non-cum:acicular cumulate non-cum:spotted cumulate cumulate cumulate

UTM NAD 83 Northing 5529523 5529523 5529523 5529523 5529636 5529659 5529659 5529590 5529571 5529367 5529367 5529367

NAD 83 Easting 687603 687603 687603 687603 687613 687672 687672 687631 687623 687583 687583 687583

SiO2 39.52 47.52 43.45 44.41 42.7 75.45 55 41.06 50.85 42 42.47 42.27

TiO2 0.36 0.42 0.41 0.43 0.39 0.21 0.723 0.28 0.71 0.39 0.42 0.36

o Al2O3 6.97 19.32 12.06 16.4 13.24 13.36 16.65 8.05 17.91 8.62 8.63 8.43

x Fe2O3 14.83 5.36 11.66 8.66 11.41 1.7 7.5 13.67 7.91 13.41 13.06 13.33

i MnO 0.23 0.1 0.19 0.18 0.2 0.02 0.14 0.22 0.15 0.21 0.21 0.21

d MgO 27.45 8.61 19.72 13.69 19.46 0.69 5.22 27.18 6.35 25.95 25.46 25.44

e CaO 3.59 12.55 7.11 9.83 6.93 1.24 7.18 3.94 10.44 4.45 4.93 5

s Na2O 1.24 1.83 1.28 1.35 1.45 4.11 3.13 0.86 3.05 0.91 1.02 0.95

K2O 0.42 1.06 0.32 1.33 0.59 1.62 1.4 0.44 0.77 0.48 0.55 0.49

w P2O5 0.11 0.13 0.126 0.147 0.143 0.037 0.25 0.116 0.17 0.125 0.121 0.122

t Cr2O3 0.31 0.07 0.19 0.12 0.19 <0.01 - 0.3 0.01 0.31 0.28 0.28

% SrO 0.02 0.06 0.02 0.05 0.03 0.04 - 0.02 0.06 0.02 0.02 0.02

BaO 0.01 0.02 0.01 0.04 0.02 0.06 0.06 0.01 0.04 0.01 0.02 0.02

LOI 4.78 2.8 3.31 3.23 3.15 1.1 1.95 3.67 1.41 3.07 2.62 2.98

Total 99.84 99.86 99.86 99.86 99.91 99.63 99.15 99.82 99.84 99.97 99.8 99.9

FeO (by titration) n/a n/a n/a n/a n/a n/a 5.14 n/a n/a n/a n/a n/a

FeO* 13.3 4.8 10.5 7.8 10.3 1.5 11.9 12.3 7.2 12.07 11.75 11.99

Natural wt% Fe2O3/FeO n/a n/a n/a n/a n/a n/a 1.46 n/a n/a n/a n/a n/a

Used wt% Fe2O3/FeO 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3

wt% Ap 0.27213804 0.31225217 0.305948834 0.35564471 0.346393432 0.087250552 0.569153211 0.283524611 0.403232576 0.303172316 0.292361392 0.295688917

wt% Il 0.731287791 0.82832478 0.8174315 0.85419442 0.775688716 0.40660715 1.351502128 0.561927207 1.382783832 0.776664386 0.833245921 0.716418796

wt% Or 2.647050292 6.48611002 1.97945016 8.1972276 3.640843058 9.731903886 8.119579761 2.739692275 4.652793194 2.965767497 3.38542873 3.025433635

wt% Ab 10.31180921 16.0341242 11.33757757 11.6536246 12.8124935 35.35414405 25.99354801 7.667667442 26.38995031 8.051058179 8.990148519 8.3990635

wt% An 13.02411769 42.8394377 27.44319139 36.2550228 29.10966612 6.012802654 26.74004981 17.70764798 33.64627972 18.83945299 18.06685404 18.0660554

C wt% C 0 0 0 0 0 2.724298165 0 0 0 0 0 0

I wt% Mt 4.888391316 1.71483649 3.772830664 2.79157977 3.681243454 0.534287408 4.006076049 4.452987256 2.519065222 4.334673762 4.20519447 4.304353845

wt% Hm 0 0 0 0 0 0 0 0 0 0 0 0

P wt% Di 4.16432442 16.6163572 6.908901402 10.9145318 4.669237828 0 5.518266142 1.678032639 14.79054952 2.716190359 5.264492197 5.612693398

W wt% Wo 0 0 0 0 0 0 0 0 0 0 0 0

wt% Hy 0 2.82239551 11.65840408 0 2.916154856 3.37522952 23.6817715 10.00491484 13.42765159 12.09875685 9.581264439 10.55612459

wt% Ol 63.48463301 12.3461619 35.77626441 28.8369473 42.04827903 0 0 54.90360575 2.787694031 49.91426367 49.38101029 49.02416792

wt% Q 0 0 0 0 0 41.77347661 4.020053383 0 0 0 0 0

wt% Ne 0.476248228 0 0 0.14122706 0 0 0 0 0 0 0 0

SiO2 Def. 0 0 0 0 0 0 0 0 0 0 0 0

Mineral SUM 100 100 100 100 100 100 100 100 100 100 100 100

N Mol% Al2O3 0.068333333 0.18941176 0.118235294 0.16078431 0.129803922 0.130980392 0.163235294 0.078921569 0.175588235 0.084509804 0.084607843 0.082647059

o Mol% Na2O 0.02 0.02951613 0.020645161 0.02177419 0.023387097 0.066290323 0.050483871 0.013870968 0.049193548 0.014677419 0.016451613 0.015322581

r Mol% K2O 0.004458599 0.01125265 0.003397028 0.0141189 0.00626327 0.017197452 0.014861996 0.004670913 0.008174098 0.005095541 0.005838641 0.005201699

m Mol% CaO 0.06403853 0.22386729 0.126828398 0.17534784 0.123617553 0.022119158 0.12807706 0.070281841 0.18622904 0.079379237 0.087941491 0.089190153

Mol% A/CNK 0.772153111 0.71574433 0.783686843 0.76114185 0.846908618 1.240263197 0.843929397 0.888519049 0.720815369 0.852324066 0.767545165 0.753292497

Mol% A/NK 2.793836806 4.64599998 4.917825688 4.47953397 4.377818465 1.568857147 2.498020186 4.256395019 3.060753707 4.27400858 3.795732556 4.026794714

Alumina class Metaluminous MetaluminousMetaluminous MetaluminousMetaluminous Peraluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous

Rock Mg# 82.32538126 80.1723471 80.97153439 79.9115515 81.10824332 50.52101916 49.86479479 83.33881767 66.62614986 82.9590907 83.06450899 82.76695977

Mineral Mg# 84.46943882 83.6174158 83.45367102 82.7075346 83.52735752 58.47564352 55.09386499 85.29948327 71.92596873 85.12773864 85.27111773 84.91408887

Wt% Na2O-K2O<>0 sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic

Plag Ab% 47.6942644 28.4280587 30.47940915 25.8564296 31.83794734 86.19513383 50.77805111 31.48444611 45.42590012 31.20112377 34.55785845 33.03734174

Plag An% 52.3057356 71.5719413 69.52059085 74.1435704 68.16205266 13.80486617 49.22194889 68.51555389 54.57409988 68.79887623 65.44214155 66.96265826

211

Table A4-1. (Continued). Trace element analyses for intrusions from the Conuma River and Leagh Creek localities.

SAMPLE DM05-212A DM05-212C KF 07-A3 KF 07-A4 KF 07-B4 KF07-D4 KF07-D5 KF 07-E1 KF 07-F1 KF 07-JN1 KF 07-JN2 KF 07-JN2-2

Locality Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma

Rock type hornblendite hbl gabbro hornblendite hbl gabbro hornblendite trondhjemite hbl diorite hornblendite hbl gabbro hornblendite hornblendite hornblendite

Intrusion type sheet 1 sheet 2 sheet 3 sheet 4 sheet or stock stock chill mafic enclave sheet sheet or stock sheet sheet sheet

Texture cumulate cumulate cumulate cumulate cumulate non-cumulate non-cum:acicular cumulate non-cum:spotted cumulate cumulate cumulate

UTM NAD 83 Northing 5529523 5529523 5529523 5529523 5529636 5529659 5529659 5529590 5529571 5529367 5529367 5529367

NAD 83 Easting 687603 687603 687603 687603 687613 687672 687672 687631 687623 687583 687583 687583

Cs 0.41 0.84 0.15 0.83 0.55 0.7 0.2 0.41 0.4 0.49 0.54 0.44

Rb 9.7 30.5 7 55.7 13.6 35.6 40 12.6 15.7 11.1 13.4 12.7

Ba 112 273 82.2 312 202 453 127.5 316 128.5 142 123

Th 0.42 0.69 0.71 0.74 0.72 12.15 1.4 0.6 1.03 0.55 0.61 0.64

U 0.23 0.34 0.33 0.39 0.38 1.85 - 0.21 0.37 0.27 0.25 0.51

K 3486 8798 2656 11039 4897 13446 11620 3652 6391 3984 4565 4067

Nb 1.5 2.4 2 2.4 2.2 3.1 - 1.6 3.4 1.8 1.9 1.7

t Ta 0.1 0.2 0.1 0.1 0.1 0.3 0.3 0.1 0.2 0.1 0.1 0.1

r La 3.9 7.9 5.4 7.1 6.9 123.5 14.7 4.6 9.6 5 5 4.6

a Ce 9.6 15.7 11.4 14.6 13.7 179 24 9.4 20.2 10.6 10.9 10.4

c Pb 5 6 5 5 5 5 - 5 5 5 5 5

e Pr 1.06 1.74 1.55 1.84 1.8 15.7 - 1.19 2.57 1.37 1.42 1.32

Sr 173 605 162.5 413 262 280 - 222 571 169 169.5 164.5

e P 479.6 566.8 549.36 640.92 623.48 161.32 1090 505.76 741.2 545 527.56 531.92

l Nd 4.5 7.4 6.7 7.7 7.5 45.2 9 5.2 11.5 6.1 6.4 6

e Sm 1.01 1.81 1.59 1.79 1.7 4.89 2.78 1.26 2.61 1.47 1.56 1.41

m Zr 24 41 32 43 35 72 132 27 54 28 30 31

e Hf 0.6 1.1 0.8 1.1 0.9 1.8 2.2 0.7 1.5 0.8 0.8 0.8

n Eu 0.33 0.67 0.52 0.63 0.57 0.57 0.86 0.34 0.89 0.44 0.48 0.46

t Gd 1.04 1.7 1.55 1.76 1.58 4.91 1.07 2.47 1.32 1.4 1.39

s Ti 2160 2520 2460 2580 2340 1260 4338 1680 4260 2340 2520 2160

Tb 0.18 0.31 0.24 0.27 0.23 0.36 0.5 0.16 0.41 0.22 0.24 0.21

p Dy 0.91 1.75 1.47 1.81 1.34 1.25 - 1.04 2.42 1.36 1.5 1.28

p Y 5.7 9.9 7.8 10.3 7.9 7 17 5.6 12.2 6.9 7.7 6.8

m Ho 0.22 0.37 0.29 0.4 0.3 0.25 - 0.21 0.49 0.27 0.3 0.26

Er 0.6 1.03 0.89 1.17 0.83 0.88 - 0.63 1.33 0.76 0.87 0.74

Tm 0.1 0.14 0.12 0.16 0.12 0.12 - 0.09 0.2 0.11 0.12 0.12

Yb 0.58 0.86 0.89 1.09 0.79 1 1.81 0.63 1.29 0.78 0.84 0.75

Lu 0.08 0.14 0.12 0.15 0.14 0.18 0.28 0.09 0.22 0.12 0.13 0.11

Zn 124 42 81 52 146 18 - 102 61 104 103 123

Mn 1782.5 775 1472.5 1395 1550 155 1085 1705 1162.5 1627.5 1627.5 1627.5

V 31 107 94 107 100 12 166 78 202 111 104 87

Sc 3 7 2 4 2 1 20.2 2 5 2 2 2

Co 108.5 30 80.2 48.3 82.7 2.8 25.2 106.5 28.8 99.1 94.4 100.5

Cu 47 16 68 6 50 2 24 45 78 34 21 31

Cr 2340 580 1250 700 1340 2 200 2060 80 2230 1940 2200

Ni 994 144 494 287 526 0.9 59 827 43 839 767 823

Ga 7 13.3 9.4 10.8 9.8 9.5 7 15.1 7.8 7.8 7.8

212

Table A4-2. Whole rock geochemistry analyses for intrusions from the Conuma River and Leagh Creek localities - major and minor oxides and CIPW norm. Abbreviations: hbl=hornblende, non-cum=non-cumulate, aphyr=aphyric, plag=plagioclase. Note: FeO* calculated as FeO*=FeO+0.8998Fe2O3.

SAMPLE KF07-L1 KF 07-M2 KF07-P KF 07-Q2 KF 07-R2 KF08-10 KF08-11B KF08-35 DM06-38 KF08-37 KF08-40-21A KF08-40-21B KF-08-40-21C KF08-52A KF08-52B

Locality Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Leagh Leagh Leagh Leagh Leagh Leagh Leagh

Rock type hyb diorite hornblendite hbl gabbro hornblendite hbl diorite tonalite hbl diorite basalt hbl gabbro basalt hbl diorite hbl diorite hbl diorite trondhjemite tonalite

Intrusion type stock stock stock sheet stock host chill mafic enclave country rock stock country rock chill mafic enclave stock stock stock stock

Texture non-cumulate cumulate non-cumulate cumulate non-cumulate non-cumulate non-cum: acicular aphyr to plag phyr non-cumulate aphyr to plag phyr non-cum: acicular non-cum: spotted non-cum: spotted non-cumulate non-cumulate

UTM NAD 83 Northing 5529053 5529329 5528858 5529582 5529189 5528764 5528690 5528577 5522811 5522143 5522863 5522863 5522863 5523613 5523613

NAD 83 Easting 687512 686944 687356 687565 687663 686959 686869 686758 687662 685370 686295 686295 686295 688336 688336

SiO2 73.88 46.66 53.39 42.38 58.57 67.5 50.09 48.52 50.02 47.42 48.47 49.01 47.24 76.1 69.58

TiO2 0.163 0.46 0.601 0.24 0.44 0.476 1.367 1.815 1.09 1.801 0.915 0.968 1.23 0.149 0.393

o Al2O3 13.33 11.75 14.59 8.46 9.41 16 17.29 13.83 18.02 14.23 16.75 18.18 19.54 12.35 15.15

x Fe2O3 1.8 10.88 1.31 12.78 7.49 1.16 9.94 14 10.09 13.36 10.16 2.77 12.14 1.58 3.42

i MnO 0.03 0.2 0.151 0.2 0.17 0.07 0.212 0.241 0.17 0.178 0.19 0.155 0.21 0.03 0.07

d MgO 0.34 18.47 7.57 26.06 11.72 1.16 5.28 7.07 5.37 6.05 5.9 5.29 4.25 0.3 0.88

e CaO 1.86 6.02 8.76 4.91 6.78 4.27 6.78 9.56 7.06 10.37 9.89 10.11 9.63 1.1 3.94

s Na2O 3.76 1.29 2.41 0.97 2.07 4.13 4.06 2.6 4.13 3.08 3.63 3.26 3.59 3.8 4.84

K2O 3.33 1.03 1.4 0.52 0.72 1.66 1.36 0.65 1.4 0.22 0.71 0.93 0.53 3.39 0.43

w P2O5 0.05 0.157 0.16 0.083 0.056 0.17 0.31 0.15 0.35 0.17 0.17 0.22 0.5 0.05 0.13

t Cr2O3 - 0.13 - 0.29 0.15 - - - 0.01 - - - - - -

% SrO - 0.02 - 0.02 0.02 - - - 0.06 - - - - - -

BaO - 0.03 - 0.02 0.03 - - - 0.05 - - - - - -

LOI 0.32 2.63 2.02 2.89 2.08 0.6 2.24 1.23 2.29 1.62 2.5 1.17 0.68 0.46 0.49

Total 98.87 99.73 98.81 99.83 99.71 100.4 98.93 98.82 100.05 98.5 99.29 98.75 99.54 99.31 99.32

FeO (by titration) 2.83 n/a 5.81 n/a n/a 2.84 6.47 11.1 n/a 10.4 6.66 6 6.59 1.65 2.99

FeO* 4.44 9.78 7 11.5 6.73 3.88 15.41 23.7 9.07 22.4 15.8 8.5 17.5 3.07 6.06

Natural wt% Fe2O3/FeO 0.64 n/a 0.23 n/a n/a 0.4 1.54 1.26 n/a 1.28 1.53 0.46 1.84 0.96 1.14

Used wt% Fe2O3/FeO 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3

wt% Ap 0.114427203 0.378894034 0.385910195 0.201049279 0.134180953 0.396485298 0.701351174 0.319709323 0.837664198 0.369870061 0.383150945 0.526614527 1.10728234 0.115434981 0.296568911

wt% Il 0.306292342 0.911517899 1.190227543 0.477336808 0.865654869 0.911537152 2.539402858 3.176361517 2.141991102 3.217386432 1.693289941 1.902544251 2.236571238 0.282450894 0.736146202

wt% Or 19.41421556 6.332448614 8.60222187 3.208810768 4.394927108 9.862853663 7.838429887 3.529341908 8.535840286 1.21938058 4.076577125 5.671127851 2.990064618 19.93808593 2.499004632

wt% Ab 31.38912196 11.35637876 21.20388086 8.570935081 18.09277716 35.13664265 33.20028274 20.21479927 36.05653633 23.27973375 24.58280311 28.46556435 25.42487397 32.00243841 40.2772375

wt% An 8.788531773 24.16629262 25.84552601 17.95479152 14.72711766 20.19860303 24.32000502 22.18622834 27.33622519 22.84179903 26.5375398 33.25435928 34.02265007 5.110456124 18.03872545

C wt% C 0.270583423 0 0 0 0 0.046161421 0 0 0 0 0 0 0 0.544033045 0

I wt% Mt 1.508117751 3.499495998 2.499213108 4.125704024 2.476310134 1.340366173 5.159222109 7.481258177 3.213686685 7.225620655 5.274625542 3.013718246 5.740371309 1.049830952 2.04771005

P wt% Hm 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

W wt% Di 0 4.683084342 14.76734548 5.524700362 15.69158279 0 5.462539677 17.25601741 5.306798653 20.58105964 16.78312184 13.98206714 7.200522824 0 0.313095127

wt% Wo 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

wt% Hy 6.121607152 25.15852651 20.81943475 9.029714495 31.12324201 7.123927121 1.649701094 6.512060411 3.548394007 0 0 4.431957163 0 4.380124374 8.944674086

wt% Ol 0 23.51336122 0 50.90695767 0 0 18.88698582 19.32422365 13.06066746 20.63380758 17.81730583 8.752047186 19.33938958 0 0

wt% Q 32.08710283 0 4.72241146 0 12.61802444 24.98342349 0 0 0 0 0 0 0 36.57714529 26.84683805

wt% Ne 0 0 0 0 0 0 0 0 0 0.63 2.85 0 1.94 0 0

SiO2 Def. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Mineral SUM 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

N Mol% Al2O3 0.130686275 0.115196078 0.143039216 0.082941176 0.092254902 0.156862745 0.169509804 0.135588235 0.176666667 0.139509804 0.164215686 0.178235294 0.191568627 0.121078431 0.148529412

o Mol% Na2O 0.060645161 0.020806452 0.038870968 0.015645161 0.033387097 0.066612903 0.065483871 0.041935484 0.066612903 0.049677419 0.058548387 0.052580645 0.057903226 0.061290323 0.078064516

r Mol% K2O 0.035350318 0.010934183 0.014861996 0.00552017 0.007643312 0.017622081 0.014437367 0.006900212 0.014861996 0.002335456 0.007537155 0.009872611 0.005626327 0.035987261 0.004564756

m Mol% CaO 0.033178737 0.107384945 0.156261149 0.087584731 0.120941848 0.076168391 0.120941848 0.170531573 0.125936497 0.184980378 0.176418123 0.18034249 0.171780235 0.019621834 0.070281841

Mol% A/CNK 1.011705569 0.828000712 0.68115822 0.762677051 0.569572245 0.977926712 0.843907196 0.61808781 0.851769336 0.588665718 0.677167852 0.734095619 0.814112447 1.0357488 0.971344783

Mol% A/NK 1.361379461 3.629293533 2.662038465 3.918728033 2.248451928 1.862204251 2.120960681 2.776416554 2.168356989 2.682216695 2.484895805 2.85389912 3.015425406 1.244669396 1.797539882

Alumina class Peraluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Metaluminous Peraluminous Metaluminous

Rock Mg# 14.77304718 81.02687611 70.99690238 83.68660238 79.76502095 40.36054969 43.68048019 40.31046192 57.2683031 37.91862317 45.80719692 58.48469091 35.472558 18.11315812 24.7387886

Mineral Mg# 17.24524713 83.60207128 75.49125463 85.5915947 82.73041707 47.49473251 49.81252999 46.06717672 64.05977776 43.80617299 50.9309368 65.0037246 40.72279458 21.20027116 28.97276182

Wt% Na2O-K2O<>0 sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic sodic

Plag Ab% 79.13480216 33.2750695 46.54233525 33.62473518 56.59334531 64.87931382 59.38515853 49.15987762 58.33003396 53.17788888 54.41083183 47.60067214 47.49609465 86.92852338 70.3246386

Plag An% 20.86519784 66.7249305 53.45766475 66.37526482 43.40665469 35.12068618 40.61484147 50.84012238 41.66996604 46.82211112 45.58916817 52.39932786 52.50390535 13.07147662 29.6753614

213

Table A4-2. (Continued). Trace element analyses for intrusions from the Conuma River and Leagh Creek localities.

SAMPLE KF07-L1 KF 07-M2 KF07-P KF 07-Q2 KF 07-R2 KF08-10 KF08-11B KF08-35 DM06-38 KF08-37 KF08-40-21A KF08-40-21B KF-08-40-21C KF08-52A KF08-52B

Locality Conuma Conuma Conuma Conuma Conuma Conuma Conuma Conuma Leagh Leagh Leagh Leagh Leagh Leagh Leagh

Rock type hyb diorite hornblendite hbl gabbro hornblendite hbl diorite tonalite hbl diorite basalt hbl gabbro basalt hbl diorite hbl diorite hbl diorite trondhjemite tonalite

Intrusion type stock stock stock sheet stock host chill mafic enclave country rock stock country rock chill mafic enclave stock stock stock stock

Texture non-cumulate cumulate non-cumulate cumulate non-cumulate non-cumulate non-cum: acicular aphyr to plag phyr non-cumulate aphyr to plag phyr non-cum: acicular non-cum: spotted non-cum: spotted non-cumulate non-cumulate

UTM NAD 83 Northing 5529053 5529329 5528858 5529582 5529189 5528764 5528690 5528577 5522811 5522143 5522863 5522863 5522863 5523613 5523613

NAD 83 Easting 687512 686944 687356 687565 687663 686959 686869 686758 687662 685370 686295 686295 686295 688336 688336

Cs 1.4 0.53 0.2 0.63 0.22 0.2 1.4 0.2 0.52 2.2 0.2 0.2 0.2 0.2 0.2

Rb 120 26.1 60 13.4 17.7 40 60 9 34 9 9 50 9 100 9

Ba - 258 - 152.5 273 - - - 507 - - - - - -

Th 9.4 1.85 3.2 1.39 5.51 2.5 1 0.9 1.29 0.6 1.1 0.4 0.9 6.8 1.5

U 0.72 0.52 1.24 0.48

K 27639 8549 11620 4316 5976 13778 11288 5395 11620 1826 5893 7719 4399 28137 3569

Nb 2.8 1.4 4.5 - - - 5.8 - - - - - -

t Ta 1.3 0.2 0.3 0.1 0.5 0.3 1 0.3 0.3 0.3 0.3 0.8 0.3 0.3 0.3

r La 19.5 8.3 12 4.9 11.6 12 12.3 7.7 15.9 7.84 8.33 8.82 11.9 15.3 13.2

a Ce 29 16.5 25 9.3 26.8 21 29 20 37.6 20 23 21 27 28 20

c Pb - 5 - 5 5 - - - 6 - - - - - -

e Pr - 2.01 - 1.1 3.35 - - - 4.57 - - - - - -

Sr - 224 - 170 173.5 - - - 451 - - - - - -

e P 218 684.52 697.6 361.88 244.16 741.2 1351.6 654 1526 741.2 741.2 959.2 2180 218 566.8

l Nd 9 8.4 9 4.4 13.4 8 19 13 19.1 13 14 11 16 9 10

e Sm 1.51 1.91 2.45 0.98 2.9 1.77 5.41 3.83 4.22 3.94 3.9 3.2 4.54 1.89 1.75

m Zr 106 55 74 40 64 206 38 116 142 98 60 57 48 97 174

e Hf 4.2 1.4 3.1 1 2.3 5.7 2.5 3.9 3.3 3.9 2.5 2.4 2.4 4.3 5.6

n Eu 0.57 0.56 0.95 0.34 0.67 1.02 1.79 1.47 1.37 1.6 1.24 1.17 1.71 0.57 1.15

t Gd - 1.76 - 0.95 2.63 - - - 4.06 - - - - - -

s Ti 978 2760 3606 1440 2640 2856 8202 10890 6540 10806 5490 5808 7380 894 2358

Tb 0.2 0.27 0.5 0.14 0.45 0.2 1.2 0.8 0.73 0.9 1 0.7 1.2 0.3 0.3

p Dy - 1.69 - 0.88 2.94 - - - 4.11 - - - - - -

p Y 7 9.9 11 5.1 15.9 5 33 23 24.8 23 23 16 28 9 3

m Ho - 0.36 - 0.18 0.61 - - - 0.88 - - - - - -

Er - 1.07 - 0.56 1.84 - - - 2.58 - - - - - -

Tm - 0.17 - 0.1 0.29 - - - 0.37 - - - - - -

Yb 1.14 1.11 1.65 0.56 2.08 0.95 3.66 2.38 2.41 2.5 2.57 2 3.02 1.26 1.15

Lu 0.18 0.17 0.25 0.09 0.33 0.15 0.5 0.35 0.39 0.29 0.34 0.31 0.46 0.23 0.16

Zn - 88 - 73 65 - - - 90 - - - - - -

Mn 232.5 1550 1170.25 1550 1317.5 542.5 1643 1867.75 1317.5 1379.5 1472.5 1201.25 1627.5 232.5 542.5

V 13 112 179 78 125 55 228 384 270 379 291 265 229 8 38

Sc 2.5 2 32.8 2 2 6.9 37.8 43.7 6 44.7 41.5 40.2 26.2 3.3 5.4

Co 1.9 66.9 38.1 99.2 40.8 8.2 24 51 30.7 55.4 42.3 35.5 25.3 2.5 5.2

Cu 4 20 18 18 11 12 28 46 62 164 28 75 37 3 10

Cr 5 910 478 1940 1100 6.8 13.1 162 40 150 85.3 68.4 0.4 85.8 111

Ni 7 405 105 746 251 7 15 75 34 97 22 22 6 3 3

Ga 9.3 6.8 9.5 17.9

214

ERROR ANALYSES

Excel spreadsheet program, designed by Derek Thorkelson, Simon Fraser

University, was used to calculate the extent of error in whole rock geochemical

analyses of the Conuma River and Leagh Creek samples, when compared to

duplicate geochemical analyses and reference standards. Only two duplicate

analyses were obtained from the ALS Chemex laboratories. Two certified

standards (MRG-1 and SY-2; K. Govinderaju, 1994) were analyzed by ALS

Chemex labs.

The program requires values of oxides or elements from the samples,

from duplicates of the same samples, from certified standards and standardized

values from certified standards. Then the program can calculate relative and

absolute error in sample analyses. Relative and absolute errors are also

expressed graphically by error envelope (Fig. 106). Errors and uncertainty is

graphically represented in Table 27 and Fig. 107. Error envelope is defined by

three lines. The central line is line of unity. Two outer lines can either converge or

diverge from each other (diverge or converge with respect to the line of unity).

The magnitude of convergence or divergence interacts with numerical values for

relative and absolute error. As the error increases, lines diverge and vice versa.

The distance of the outer lines from the line of unity needs to be adjusted (by

entering error numerical values) to locate all samples, duplicates, standards

within the envelope. The higher scatter in data, the further the outer envelope

lines will be positioned (and vice versa) and this correlates directly to the

numerical value of entered relative and absolute error. In the error envelope plot,

215

standardized values of certified standards and sample values (X-axis) are plotted

against duplicate samples and duplicates of certified standards (Y-axis).

Use of duplicates is meant to define precision in geochemical analyses,

use of standards is in reference to accuracy. If precision and accuracy would be

perfect, all data point would fall on the line of unity and outer lines of error

envelope would merge into a line of unity. Relative and absolute errors would be

zero. Error in lower concentrations is considered by the program as absolute,

error, in higher concentrations is considered as relative error. More data from

duplicate samples are available, the better result for absolute and relative error

can be obtained.

0

5

10

15

20

0 5 10 15 20

Analysis 1 and accepted standard value

An

alys

is 2

and

mea

sure

d st

anda

rds

Sm (ppm)

Absolute error = 0.14 ppmRelative error = 9.9%

A

0

50

100

150

200

250

300

350

400

450

500

0 50 100 150 200 250 300 350 400 450

Analysis 1 and accepted standard value

Analy

s is

2 a

nd m

easu

red s

tandard

s

BBa (ppm)

Absolute error = 14.14 ppmRelative error = 7.1%

Figure A4-1. A: An example of an error envelope for element Sm (ppm). Diagonal lines are error envelope, with the central line=a line of unity. Absolute error of 0.14 ppm is expressed by a convergence of outer envelope lines in “zero” corner of the plot. Relative error of 9.9% is expressed by a divergence of envelope lines. All samples need to fit within the envelope. Triangles are certified standards, diamonds are samples which have been analyzed twice. B: Another example of an error envelope for Ba element. Absolute error 14.14 ppm is expressed by nearly parallel outer lines of envelope in “zero” corner of the plot. Relative error of 7.1% is expressed by slight divergence of envelope outer lines. Most samples fall within the envelope, so the error envelope is not as large as required and will need to be expanded by increasing the absolute error, the relative error, or both.

216

Analyzed Mean value Relative error Absolute error Total uncertainty

element (MV) (RE) (AE) MV x RE/100 + AE

ppm % ppm ppm

Cs 0.54 1.414 0.09898 0.1066156

Rb 13.4 4.242 4.242 4.810428

Ba 110 7.07 14.14 21.917

Th 0.61 4.242 14.14 14.1658762

U 0.25 2.828 8.484 8.49107

Nb 1.9 9.898 0.12726 0.315322

Ta 0.1 21.21 0.000141 0.021351

La 5 15.554 0.2121 0.9898

Ce 10.9 15.554 1.414 3.109386

Pb 5 60.802 3.535 6.5751

Pr 1.42 60.802 3.535 4.3983884

Sr 83 6.363 1.1312 6.41249

Nd 6.4 4.242 0.5656 0.837088

Sm 1.56 9.898 0.1414 0.2958088

Zr 30 2.121 3.535 4.1713

Hf 0.8 9.898 0.09898 0.178164

Eu 0.48 3.535 0.02828 0.045248

Gd 1.4 16.968 0.08484 0.322392

Tb 0.24 21.21 0.04242 0.093324

Dy 1.5 19.796 0.12726 0.4242

Y 7.7 12.726 0.5656 1.545502

Ho 0.3 22.624 0.02828 0.096152

Er 0.87 32.522 0.08484 0.3677814

Tm 0.12 2.828 0.09898 0.1023736

Yb 0.84 1.414 0.8484 0.8602776

Lu 0.13 39.592 0.02828 0.0797496

Zn 32 28.28 0.001414 9.051014

V 26 19.796 1.414 6.56096

Cu 23 1.414 9.898 10.22322

Cr 563 9.191 73.528 125.27333

Ni 498 7.07 1.414 36.6226

0

20

40

60

80

100

120

140

Cs Rb Ba Th U Nb Ta La Ce Pb Pr Sr Nd Sm Zr Hf Eu Gd Tb Dy Y Ho Er Tm Yb Lu Zn V Cu Cr Ni

Total uncertainty

ppm

Figure A4- 2. Whole rock analyses of trace elements from Conuma River intrusions with calculated relative and absolute errors, and total uncertainty. Total uncertainty values are also graphically expressed in a simple bar diagram below.

217

30

20

10

2 4 6 8Th (ppm)

La

(p

pm

)

La /

Th

= 2

5

La

/ T

h =

15

La / T

h = 7

= B

ulk

Earth

High-K

Medium-K

Low-K

Orogenic AndesiteN

-M

OR

B

E-M

OR

B

s

La / Th = 2

30

20

10

200 400 600 800 1000

Ba (ppm)

La

(ppm

)

Ba / L

a =

4

Ba / L

a =

11 =

Bul k

Earth

Ba / L

a =

15

Ba / La = 80

N-M

OR

B

E-M

ORB

Orogenic Andesite

High-K

Medium-K

Low-K








Legend

Figure A4- 3. Tectonic setting discriminant diagrams (Gill 1981). In both plots, samples fall in the orogenic andesite field, which is in agreement with an arc setting. In Th vs La plot many samples fall out of the orogenic andesite field due to their low Th and La abundances. Ba vs La plot shows more clearly tectonic affinity of samples. N-MORB=normal ocean-ridge basalt, E-MORB=enriched ocean ridge basalt.

218

Zr 3*Y

pmTi/100

W PB AR C ( tho)

C alc-Alk

Ti/100

A

Sr/2

pmTi/100Ti/100

M OR B

AR C

C a lc-A lk

Zr

B

Zr/4 Y

2*Nb

N-M ORB& Arc

E-M ORB

W PTB& Arc

W PA

W PTB

C

La/10 Nb/8

Y /15

BAB

Arc-Calc

CFB Cont

E-M ORB

N-M ORB

ARC-thol

D

Hf Ta*3

Rb/30

W PBARC

Syn-coll

late,

post-coll

E








Legend

5.21 for subalkaline non-fractionated basalts

Th Nb/16

Zr/117

N-MORB

E-MORB

OIB(Rift)

Arc

F

Figure A4- 4. Triangular tectonic discriminant plots show the CRIC and LCIC samples in arc, calc-alkaline and tholeiitic setting. Karmutsen country rock plots usually as within plate basalt with oceanic affinity. A and B: (Pearce and Cann 1973) C: (Meshede 1986) D: (Cabanis and Lecolle 1989) E: (Harris et al. 1986) F: (Wood 1980) . N-MORB = normal mid-ocean ridge basalt, E-MORB=enriched mid-ocean ridge basalt, WPB = within plate basalt, tho=tholeiitic, WPA=within plate alkaline, WPTB=within plate tholeiitic basalt, BAB=back arc basalt, OIB=ocean island basalt, post-coll=post-collisional, syn-coll=syn-collisional.

219

0.01

0.1

1

10

100

1000

10000

DM05-212A KF07-E1 KF07-JN1 KF07-Q2 KF07-JN2 KF07-JN2-2 KF07-B4 KF07-A3 KF07-M2

SiO2

TiO2

Al2O3

FeO*

MnO

MgO

CaO

Na2O

K2O

P2O5

Cs

Rb

Ba

Th

U

Nb

Ta

La

Ce

Pr

Sr

Nd

Sm

Zr

Hf

Eu

Gd

Tb

Dy

Y

Ho

Er

Tm

Yb

Lu

V

Sc

Co

Cu

Cr

Ni

An%

Mg#SiO2 increase

Compositional variations in Conuma River hornblendites

Ma

jor

and

min

or

oxid

es (

wt%

), t

race

ele

men

ts (

ppm

)

Figure A4- 5. Compositional variations in Conuma River hornblendites in order with respect to SiO2 increase. Samples from DM05-212A to KF07-JN2-2 are olivine hornblendites. Samples KF07-B4 and KF07-A3 are megacrystic hornblendites and KF07-M2 is medium-grained hornblendite. FeO, MgO, Cr , Mn, Ni, and Co show a decreasing trend with respect to SiO2. Ti, V, Zr, Ce, Ga, Y, Sc, Nd, Nb, Pr, Sm, Gd, Th, Hf, Yb, U, Ta, Tm and An% show an increase with respect to SiO2. All oxides were normalized to 100% on volatile free basis.

220

APPENDIX 5: GEOCHRONOLOGY

Table A5-1. 40

Ar-39

Ar gas release spectra of hornblende from hornblende-plagioclase pegmatite from the Conuma River intrusive complex (sample 05-212A with a plateau age of 189.9±2.1 Ma).

DM-05-212A Hornblende

Laser Isotope Ratios

Pow er(%) 40Ar/39Ar 38Ar/39Ar 37Ar/39Ar 36Ar/39Ar Ca/K Cl/K %40Ar atm f 39Ar 40Ar*/39ArK Age

2 3548.409±0.168 8.734±0.183 8.658±0.195 10.238±0.171 36.905 2.108 73.58 0.02 1222.646±367.349 3653.98±470.53

2.4 1575.382 0.050 4.205 0.067 5.494 0.056 4.317 0.054 37.949 0.829 75.44 0.13 405.209 36.995 2087.36 112.92

2.8 612.327 0.038 1.705 0.051 4.157 0.052 1.829 0.043 30.207 0.319 81.1 0.27 116.513 13.453 878.07 80.27

3.2 60.232 0.011 0.881 0.020 4.046 0.021 0.137 0.033 32.945 0.196 59.36 3.93 24.210 1.389 220.93 11.93

3.6 32.541 0.015 0.701 0.022 3.396 0.019 0.041 0.035 27.72 0.158 28.54 10.39 23.085 0.577 211.24 4.98

4 25.486 0.013 0.609 0.018 2.885 0.018 0.021 0.031 23.565 0.137 18.05 33.23 20.891 0.359 192.19 3.13

4.4 23.103 0.016 0.575 0.019 3.095 0.021 0.015 0.036 25.285 0.13 11.01 23.81 20.508 0.383 188.85 3.35

5 23.162 0.015 0.727 0.018 3.154 0.020 0.015 0.032 25.779 0.165 11.61 28.21 20.456 0.363 188.39 3.18

Total/Average 30.805±0.003 0.665±0.005 13.766±0.003 0.034±0.006 0.505 100 20.640± 0.108

J = 0.005381±0.000006

Volume 39ArK = 117.79

Integrated Date = 202.46±1.89

Volumes are 1E-13 cm3 NPT

Neutron f lux monitors: 28.02 Ma FCs (Renne et al., 1998)

Isotope production ratios: (40Ar/39Ar)K=0.0302±0.00006, (37Ar/39Ar)Ca=1416.4±0.5, (36Ar/39Ar)Ca=0.3952±0.0004,

Ca/K=1.83±0.01(37ArCa/39ArK).

.

Abbreviations used in all tables of Appendix 5 : % 40 Ar atm = percentage of 40Ar in the analyzed gas fraction, f 39 Ar = % fraction of 39 Ar as rationed to the total amount of 39 Ar released from the sample, J = Flux correction factor, NPT = Normal Pressure and Temperature, FCs = Fish Canyon sanidine

221

Table A5-2. 40

Ar-39

Ar gas release spectra of hornblende from hornblende gabbro from the Leagh Creek intrusive complex (sample 06-38 with a plateau age of 179.7±3 Ma).

DM-06-38 Hornblende

Laser Isotope Ratios

Power(%) 40Ar/39Ar 38Ar/39Ar 37Ar/39Ar 36Ar/39Ar Ca/K Cl/K %40Ar atm f 39Ar 40Ar*/39ArK Age

2 47.604±0.057 0.371±0.143 0.172±0.384 0.215±0.232 6.158 0.075 63 0.58 13.915±16.303 234.43±257.56

2.3 24.439 0.020 0.089 0.151 0.145 0.093 0.038 0.190 6.321 0.015 19.28 4.02 18.197 2.241 300.84 34.13

2.7 27.373 0.026 0.116 0.153 0.224 0.098 0.069 0.105 9.865 0.02 47.09 3.26 13.295 2.245 224.60 35.67

3.1 16.378 0.016 0.311 0.078 0.220 0.060 0.044 0.229 9.675 0.067 28.54 3.14 9.842 3.049 168.89 49.95

3.5 11.264 0.018 0.951 0.024 0.468 0.036 0.008 0.107 21.195 0.217 3.33 26.85 10.619 0.330 181.59 5.37

3.8 11.061 0.010 0.838 0.016 0.464 0.019 0.007 0.093 21.029 0.191 3.72 40.71 10.484 0.226 179.38 3.69

4 11.553 0.011 0.745 0.020 0.459 0.035 0.013 0.197 20.771 0.17 3.81 10.95 10.400 0.794 178.03 12.94

4.2 12.596 0.012 0.792 0.037 0.475 0.046 0.026 0.262 21.537 0.181 2.34 4.25 10.407 2.068 178.13 33.70

4.5 11.828 0.012 0.813 0.021 0.471 0.036 0.019 0.120 21.347 0.186 1.72 6.25 10.329 0.697 176.86 11.38

Total/Average 11.998±0.003 0.781±0.005 10.675±0.003 0.007±0.059 19.683 0.125 100 10.477± 0.128

J = 0.009972±0.000010

Volume 39ArK = 33.45

Integrated Date = 186.17±4.15

Volumes are 1E-13 cm3 NPT

Neutron flux monitors: 28.03 Ma FCs (Renne et al. , 1998)

Isotope production ratios: (40Ar/39Ar)K=0.0302±0.00006, (37Ar/39Ar)Ca=1416.4±0.5, (36Ar/39Ar)Ca=0.3952±0.0004,

Ca/K=1.83±0.01(37ArCa/39ArK).

222

Figure A5- 1. Argon isotope correlation diagrams with an inverted isochron. A: Hornblende sample DM05-212A from the CRIC has an isochron age of 184±13 Ma. B: DM06-38 hornblende sample from the LCIC has an isochron age of 178.4±7.5 Ma. All data points define a straight line, although in A they are defined only by the minimum criterion of three points (steps) and large error envelopes. Mean Squared Weighted Deviates (MSWD) are less than 1. Isochron ages yielded larger errors than the plateau ages.

223

Figure A5-2. Radiometric dating of the Bonanza island arc on Vancouver Island. A summary of radiometric ages of the Island Plutonic Suite and Westcoast Crystalline Complex (pink and purple retrospectively) and Bonanza Group (bluish green) units, also including two new Ar-Ar ages (bold italic). Published absolute ages of rocks from the Bonanza island arc are shown indicating location of dated samples and superscript number indicates the publications from which they were taken:

1(DeBari et al. 1999),

2(Fecova et al. 2008),

3(Isachsen 1986),

4(Muller et al. 1974). U-Pb ages were obtained from

zircons and K-Ar and Ar-Ar from hornblendes (Hbl). Yellow stars indicate some previously studied locations of the Bonanza island arc. The outline of the island and distribution unit taken from Map Place: BCGS 2005 layers (Massey et al. 2005).

224

APPENDIX 6: CRYSTALLIZATION MODELING

Crystallization modeling of geochemical data from Conuma River and

Leagh Creek intrusive varieties was performed by using Stonergram ver.3.0,

designed and provided by Derek Thorkelson, Simon Fraser University. This

program allows data modeling of processes such as crystal fractionation, crystal

accumulation in closed system and magma mixing, restite formation,

metasomatism and assimilation in an open system. Modeling of a closed system

is constrained by a conserved, immobile element. Ideal mineral stoichiometries

were used for stonergrams and electron microprobe mineral compositions for

Pearce Element Ratio. Using electron microprobe data or ideal stoichiometries

as input showed minimal differences in the final results.

The major difference between constrained and unconstrained

crystallization modeling is that constrained modeling involves normalization of

geochemical data to concentration values of immobile, conserved trace element,

i.e., one which partitions almost entirely into the melt and is not significantly

affected by subsequent alteration. The rationale for using a conserved element

in modeling igneous systems is the same as that applied to Pearce Element

Ratio analysis, as described by Pearce (1968) and Russell and Stanley (1990).

Unconstrained modeling results are not controlled by a conserved element factor

and are not as reliable in determining the amount of fractionation or other closed

system processes.

225

Detailed description of crystallization modeling

In STONERGRAM program, major oxides SiO2, TiO2, Al2O3, FeO*, MgO, CaO, Na2O,

K2O and P2O5 and trace elements of parental and evolved samples are required for the input.

The oxides do not need to sum up to 100%. The parent of the Conuma samples - plagioclase phyric, quartz-

hornblende gabbro - was chosen based on Mg#, calculated using Fe3+

/Fe2+

ratio 0.3, and relatively high Cr and Ni

concentrations. The Mg value of 73.4 indicates its non-cumulate character and this is supported with non-cumulate texture

based on petrographical analyses and stock-like appearance in the field. Even if the composition of parental magma is

unknown (like in our case), one of the samples from a magmatic suite needs to be chosen as a “parent”. For example we

want to find out if a more evolved cumulate can be related to a less evolved cumulate. One of these cumulates needs to

act as a parent in order to run the mode. In our set of data, evolved samples are hornblendite, hornblende gabbro,

hornblende diorite and tonalite varieties with either higher Mg# or lower Mg# with respect to a parental sample. If any link

between an evolved sample and a parent exists, the less evolved samples with higher Mg# will relate with respect to a

parent via accumulation and more evolved samples with lower Mg# will relate with respect to a parent via fractionation.

1. The major oxides of all samples are recalculated to their molecular proportions and then to

molecular percentages, where they sum up to 100%. Molecular percentage values are used

for calculation of Fo% and Mg# for conditions with 0%Fe3+

and Fe3+

/Fe2+

ratio depending on

an alteration stage. Ratio 0.3 was chosen for our samples.

2. A conserved, immobile element (preferentially incompatible) needs to be selected, to which

molecular percentages of major oxides in all samples would be normalized. Ce was chosen to be

a conserved element for our samples (Fig. A6-1). Its concentrations values consistently double with respect to the

compositional evolution of the evolved samples. Selection of a different partitioning coefficient for Ce will result in a

different overall percentage of mineral fractionation (or accumulation) although the proportions of the minerals in the

fractionating assemblage will not change. Elements such Zr or Nb would be also appropriate candidates to use.

Partitioning of the chosen conserved element into modeled mineral assemblage is governed by Rayleigh

fractionation. In numerical means, the program calculates “synthetic” (adjusted) concentrations of the conserved

element in parental and evolved samples, which are then used to normalize values of molecular percentages of

major oxides of all samples. In general, any element can be chosen to be one to constrain crystallization processes.

But problems can arise when compatible elements, such Ni, are chosen. As this element is incorporated in early

crystallizing phases, its use would result in a more complicated modeling.

226

0.2

0.3

0.4

0.5

0.6

2 3 4

Conserved element plot for Conuma River intrusions

Zr/Ce

La/C

e

3. The program calculates the bulk distribution coefficient (D) for the chosen conserved

element, once the minerals involved in the model are known and their relative proportions

can be specified. Ideally, the distribution coefficient of a conserved element (conserved in melt) would be 0.

Commonly this value ranges from 0.01 to 1, depending on minerals and their proportions involved in the modeled

process. The element concentration in original magma and in residual liquid needs to be in accordance with Rayleigh

fractionation and its concentrations is calculated by the program, using the formula:

CL = Co x F(D-1)

,

where CL is the concentration of the element in the residual liquid (evolved sample), Co is the concentration of the

element in the original magma (parental sample), D is the distribution coefficient and F is the fraction of liquid after

removal of formed crystals.

4. Input of mineral chemistry of the phases involved in the modeling is required and can be

applied to processes: compositional losses (fractionated phases) and compositional gains

(accumulated phases). Input of An% in plagioclase, Fo% in olivine, En% in orthopyroxene, Di% in augite, Fe%

in pargasite, %TiO2 in magnetite and many others is required to calculate stoichiometry of mineral phases.

Alternatively, input of molecular % of mineral components available from microprobe analyses is required.

5. Input of total % losses or gains, Fe3+

/Fe2+

ratio and proportions of minerals involved in total

gains/losses is required. At the beginning of a modeling process total % are set to zero. Entering numerical

values for either total % losses or gains depends on desired modeling process. Input data from steps 4 and 5

characterizes model liquid composition.

Figure A6- 1. Conserved element plot for Conuma River intrusions. A cluster of data showing no strong trend is a good indicator that La, Zr and Ce were conserved in melt during fractionation of magmas producing Conuma River hornblendites and non-cumulate hornblende gabbro.

227

6. The graphing area shows output data: compositional curves of parental, evolved and model

liquid compositions. Both evolved and model compositions are normalized to a parental composition. Therefore

a graphical expression of a parental composition is a horizontal line with an intercept of 1 on the Y axis. The

normalized values of major oxides in an evolved sample are plotted as points that are connected to produce a curve

of a particular shape. At the beginning of modeling, where no process is involved yet, model curve has a shape of a

horizontal line and overlaps with the parental line. Model curve responds to the input of data (such total % amount of

gains/accumulation or losses/fractionation, compositions and proportions of phases selected to be involved in

modeling processes) by acquiring a relevant shape. Once the model curve overlaps with the curve of evolved

sample, it can be concluded (if geologically plausible) that parental and evolved samples can be genetically related.

The final input data, resulting in matching curves, characterizes the process through which those two samples can be

related.

7. Model and residual liquid compositions are also an output of the program. Program calculates

model liquid composition in molecular % and recalculates it back to wt%. It also calculates Fo%

and Mg# of model liquid composition. Model liquid composition can be then matched to any of the available evolved

sample compositions from a studied igneous suite, but it can be used for any other purposes. Specifically, program

calculates normalization values from rationing mol% of major oxides of an evolved sample to a parental one. The

calculated normalization values define compositional curve of the evolved sample. Compositional curve of modeled

sample is fitted to the evolved curve by error trial of an input of data (modeled data). A perfect fit defined by input

data means that parental and evolved sample can be linked through that input data. Subtracting input data from the

parental data will produce net compositional change data, which is recalculated to a model liquid composition.

Residuals represent the difference between evolved and modeled data. In an ideal case, when evolved and modeled

curves perfectly fit, all residuals result in zero values. If the fit is good, but not perfect, residuals will attain values

reflecting missing or excessive amounts of components that deviate modeled curve from evolved one.

8. Magma mixing modeling is designed similarly as described above, except this process is not

controlled by conserved element, as this process involves an open system. This type of modeling

requires input of compositions that are desired to be mixed. The program allows mixing up to four compositions in

one run and works on the principle, that one of those four compositions needs to be set as a parent and other

magma or rock compositions are being added at desired proportions. The graphing area shows a horizontal parental

compositional line, to which added magma or rock compositions are normalized. A composition of a sample (mixed

sample) that is believed to be a product of magma mixing or mingling, needs to be also part of the input data and is

also normalized to a parent and plotted in the graphing area. A model curve is then being matched by input data (%

proportions of individual rock or magmas involved in mixing and their total % gains/additions) to the curve of a mixed

228

sample. Once the match is achieved, the output data includes a specific total % additions and proportions of

magmas needed to produce a mixed sample.

In FRASPIDE program, input of trace element concentrations, including LILE, HFSE,

REE and compatible elements of a parental and evolved sample(s) are required. Graphical output

of the data has a form of trace element pattern for the modelled and evolved sample. If the

pattern is close to be identical, parental and evolved sample are genetically linked (if geologically

plausible) by modelled process of either accumulation or fractionation in a closed system (Rayleigh-

type with formula: Cl=Co*F^(D-1), where CL is the concentration of the element in the residual liquid (evolved sample), Co

is the concentration of the element in the original magma (parental sample), D is the distribution coefficient and F is the

fraction of liquid after removal of formed crystals). Programs allows for simultaneous run of two models.

Trace element values of modelled and evolved samples are normalized to the parental trace

element concentrations.

1/ Input of trace element concentrations for parental and evolved samples.

2/ Program uses the partition coefficients, mainly for use in basaltic to andesitic systems

(e.g., Rollinson 1993).

3/ Input of % proportions of mineral phase involved in the crystallization modelling.

4/ Input of total % gains/accumulation or losses/fractionation.

5/ Output of the program includes normalized evolved and model trace element values

and their graphical expression in form of trace element patterns. In ideal case, trace element

pattern of a model would overlap with evolved sample pattern and the input data would define the

relationship between parental and evolved samples.

229

SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5

Parental KF07-P 1 1 1 1 1 1 1 1 1

Model 1.95 1.44 1.11 4.37 8.50 1.06 1.03 1.00 1.59

DM05-212A 1.79 1.45 1.15 4.59 8.75 0.99 1.24 0.72 1.66

0.1

1

10

Co

nstr

ain

ed

Cu

rves:

No

rmalized

to

po

ssib

le p

are

nta

l gab

bro

(K

F07-P

)

Mineral Accumulation for Conuma River gabbro and hornblendite

Constrained by Ce

Parental

KF07-P

Model

DM05-212A

Modeling GAINS Fractionating Phases Mineral Composition Recalculated % of Phases

Expected bulk partition coefficient (D) Plagioclase (An%) 85 1.6

of "conserved" element: Ce 0.018 Olivine (Fo%) 85 95.1

Total Gains (molecular %) 170 Augite (Di%) 80 0.0

Iron Oxidation: (Fe3+

/Fe2+

) = 0.3 Orthopyroxene (En%) 85 0.0

Magnetite (%TiO2) 4 3.2

Apatite 0.1

Samples SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in

Parent: KF07-P (wt%) 53.4 0.6 14.6 7.0 7.6 8.8 2.4 1.4 0.2 equilibr. equilibr.

DM05-212A (wt%) 39.5 0.4 7.0 13.3 27.5 3.6 1.2 0.4 0.1 olivine Fe3+

/Fe2+

olivine

Model Composition (wt%) 45.4 0.4 7.0 13.3 28.0 4.0 1.1 0.6 0.1 0%Fe3+

0%Fe3+

0.30 0.30

KF07-P (mol%) 57.9 0.5 9.3 6.3 12.2 10.2 2.5 1.0 0.1 86.5 65.8 73.4 90.2

DM05-212A (mol%) 39.0 0.3 4.1 11.0 40.4 3.8 1.2 0.3 0.0 92.5 78.6 84.0 94.6

Model Composition (mol%) 41.8 0.3 3.8 10.3 38.5 4.0 1.0 0.4 0.0 92.6 79.0 84.3 94.7

Figure A6- 2. Results of crystallization modeling for the Conuma River samples. Parental sample (KF07-P=non-cumulate plagioclase phyric, quartz-hornblende gabbro) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (DM05-212A=olivine hornblendite-the least evolved Conuma River hornblendite variety) are rationed. The model liquid composition line achieved the match with evolved sample after 170 molecular % gains (accumulation) of olivine>magnetite>plagioclase and apatite. Model composition can be related to one of the more evolved hornblendite varieties found in CRIC.

230

Table A6-1. Results of crystallization modeling for the Conuma River samples. All models successfully relate hornblendite sheets (KF-E1,JN1, JN2, Q2, B4 and A3) to non-

cumulate plagioclase phyric, quartz-hornblende gabbro parent (KF07-P) by varying accumulation of olivine, minor plagioclase, ± clinopyroxene ± magnetite and apatite. Modeling graphs are equivalent to one shown in Figure 112.

Major oxides Modeling GAINS

Sample SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in Expected bulk partition coefficient (D) of "conserved" elementCe=0.023

Parent: KF07-P (wt%) 53.4 0.6 14.6 7.0 7.6 8.8 2.4 1.4 0.2 equilibr. equilibr. Total Gains (molecular %) 175

KF07-E1 (wt%) 41.1 0.3 8.1 12.3 27.2 3.9 0.9 0.4 0.1 olivine Fe3+

/Fe2+

olivine Iron Oxidation ratio (Fe3+

/Fe2+

) = 0.3


0%Fe3+

0.30 0.30 % Fractionating Phases

KF07-P (mol%) 57.9 0.5 9.3 6.3 12.2 10.2 2.5 1.0 0.1 86.5 65.8 73.4 90.2 Plagioclase Olivine Augite Orthopyroxene Magnetite Apatite

KF07-E1 (mol%) 40.2 0.2 4.6 10.1 39.6 4.1 0.8 0.3 0.0 92.9 79.8 84.9 94.9 An% =85 Fo% =85 Di% =80 En% =85 %TiO2 =1

Model Composition (mol%) 41.8 0.2 4.7 10.4 37.2 4.4 1.0 0.4 0.0 92.3 78.2 83.7 94.5 5.4 90.8 0.0 0.0 3.6 0.1




KF07-JN1 (wt%) 42.0 0.4 8.6 12.1 26.0 4.5 0.9 0.5 0.1 olivine Fe3+

/Fe2+


/Fe2+

) = 0.3


0%Fe3+



KF07-JN1 (mol%) 41.1 0.3 5.0 9.9 37.9 4.7 0.9 0.3 0.1 92.7 79.3 84.6 94.8 An% =85 Fo% =85 Di% =80 En% =85 %TiO2 =5





KF07-Q2 (wt%) 42.4 0.2 8.5 11.5 26.1 4.9 1.0 0.5 0.1 olivine Fe3+

/Fe2+


/Fe2+

) = 0.3


0%Fe3+



KF07-Q2 (mol%) 41.3 0.2 4.9 9.4 37.9 5.1 0.9 0.3 0.0 93.1 80.2 85.2 95.1 An% =85 Fo% =85 Di% =80 En% =85 %TiO2 =0.1





KF 07-JN2 (wt%) 42.5 0.4 8.6 11.8 25.5 4.9 1.0 0.6 0.1 olivine Fe3+

/Fe2+


/Fe2+

) = 0.3


0%Fe3+



KF07-JN2 (mol%) 41.5 0.3 5.0 9.6 37.1 5.2 1.0 0.3 0.1 92.8 79.4 84.7 94.8 An% =85 Fo% =85 Di% =80 En% =85 %TiO2 =6





KF07-B4 (wt%) 42.7 0.4 13.2 10.3 19.5 6.9 1.5 0.6 0.1 olivine Fe3+

/Fe2+


/Fe2+

) = 0.3


0%Fe3+



KF07-B4 (mol%) 43.7 0.3 8.0 8.8 29.7 7.6 1.4 0.4 0.1 91.8 77.1 82.8 94.1 An% =85 Fo% =85 Di% =80 En% =85 %TiO2 =5





KF07-A3 (wt%) 43.5 0.4 12.1 10.5 19.7 7.1 1.3 0.3 0.1 olivine Fe3+

/Fe2+


/Fe2+

) = 0.3


0%Fe3+



KF07-A3 (mol%) 44.3 0.3 7.2 8.9 29.9 7.8 1.3 0.2 0.1 91.8 77.0 82.7 94.1 An% =85 Fo% =85 Di% =80 En% =85 %TiO2 =5


231


Parental KF07-P 1 1 1 1 1 1 1 1 1

Model 1.31 1.09 1.13 1.96 3.34 1.07 1.04 1.00 1.44

KF07-M2 1.26 1.10 1.16 2.01 3.51 0.99 0.77 1.06 1.41

0.1

1

10

Co

nst

rain

ed

Cu

rve

s:

No

rmal

ize

d t

o p

oss

ible

par

en

tal g

abb

ro (K

F07

-P)

Mineral Accumulation for Conuma River gabbro and hornblendite

Constrained by Ce

Parental

KF07-P

Model

KF07-M2






/Fe2+



Apatite 0.3 Samples SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in


KF07-M2 (wt%) 46.7 0.5 11.8 9.8 18.5 6.0 1.3 1.0 0.2 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

KF07-P (mol%) 57.9 0.5 9.3 6.3 12.2 10.2 2.5 1.0 0.1 86.5 65.8 73.4 90.2

KF07-M2 (mol%) 47.6 0.4 7.1 8.3 28.1 6.6 1.3 0.7 0.1 91.8 77.1 82.8 94.1


Figure A6- 3. Results of crystallization modeling for the Conuma River samples. Parental sample (KF07-P=non-cumulate hornblende gabbro) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (KF07-M2=hornblendite-the most evolved Conuma River hornblendite variety) are rationed. The model liquid composition line achieved the match with evolved sample after 55 molecular % gains (accumulation) of olivine> plagioclase>magnetite and minor apatite.

232

0.000

0.200

0.400

0.600

0.800

1.000

1.200

Rb Th K La Ce Nd P Zr Sm Eu Ti Y Yb V Sc Cr Ni

No

rmalized

to

Pare

nta

l C

om

po

sit

ion

Fractional Crystallization Modeling

Model 1: 170%

gains

DM05-212A

KF07-M2

Model 2: 55%

gains

KF07-M2 and Model 2

DM05-212A and Model 1

Proportions of minerals

in the fractionating assemblage

(by weight) for two different

models of fractionation

Minerals used Model 1 Model 2

Olivine 95 92

Clino Px 0 0

Ortho Px 0 0

Plagioclase 2 6

Magnetite 3 2

Hornblende 0 0

Sum 100 100

Model 1 Model 2

% Fractionation -170 -55 Sample Location Rb Th K La Ce Nd P Zr Sm Eu Ti Y Yb V Sc Cr Ni

PARENTAL Rock Composition KF07-P Conuma 60 3.2 11620 12 25 9 698 74 2.45 0.95 3606 11 1.65 179 32.8 478 105

Other Composition 1 DM05-212A Conuma 9.7 0.42 3486 3.9 9.6 4.5 480 24 1.01 0.33 2160 5.7 0.58 31 3 2340 994

Other Composition 2 KF07-M2 Conuma 26.1 1.85 8549 8.3 16.5 8.4 685 55 1.91 0.56 2760 9.9 1.11 112 2 910 405

% fractionation Model # Rb Th K La Ce Nd P Zr Sm Eu Ti Y Yb V Sc Cr Ni

Calculated Residual Liquids -1.7 Model 1: 170% gains 0.37 0.37 0.37 0.38 0.38 0.38 0.38 0.38 0.38 0.38 0.46 0.38 0.38 0.6 0.45 5.18 3E+05

Normalized to Parental Comp. -0.55 Model 2: 55% gains 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.65 0.69 1.52 194.1

Rock Data normalized to DM05-212A 0.16 0.13 0.30 0.33 0.38 0.5 0.69 0.32 0.41 0.35 0.6 0.52 0.35 0.17 0.09 4.9 9.467

Parental Composition KF07-M2 0.44 0.58 0.74 0.69 0.66 0.93 0.98 0.74 0.78 0.59 0.77 0.9 0.67 0.63 0.06 1.9 3.857

Figure A6- 4. Results of fractional crystallization modeling for the Conuma River samples based on trace element concentrations. Parental sample (KF07-P=non-cumulate plagioclase phyric, quartz-hornblende gabbro) is plotted on the graph as a horizontal line with composition 1, to which two model liquid compositions (Model 1 and Model 2) and evolved sample compositions (KF05-212A= olivine hornblendite and KF07-M2= hornblendite) are rationed. The model liquid composition lines do not achieve matches with related evolved samples. Resolution of the problem is beyond the scope of this thesis.

233


Model Unc 1.23 1.20 2.47 0.57 0.53 3.03 1.45 2.27 1.21

DM05-212A 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

KF07-A4 1.21 1.29 2.53 0.63 0.54 2.95 1.17 3.41 1.44

0.10

1.00

10.00U

nco

nstr

ain

ed

Cu

rves:

Mix

ing

ho

rnb

len

dit

e w

ith

ho

rnb

len

de g

ab

bro

Magma Mixing for Conuma River hornblendite and hornblende gabbro

Unconstrained conditions

Model Unc

DM05-212A

KF07-A4

Modeling GAINSUnconstrained (open system) modeling

Total Gains (molecular %) 250 (mixing 1 part of DM05-212A with 2.5 parts of DM05-212C)


/Fe2+

) = 0.3


Mixing: DM05-212A (wt%) 39.52 0.36 6.97 13.30 27.45 3.59 1.24 0.42 0.11 equilibr. equilibr.

With: DM05-212C (wt%) 47.52 0.42 19.32 4.80 8.61 12.55 1.83 1.06 0.13 olivine Fe3+

/Fe 2+

olivine

Producing: Model Composition (wt%) 48.03 0.32 9.99 6.25 21.50 11.53 1.72 0.60 0.06 0%Fe3+

0%Fe3+

0.30 0.30

Matching: KF07-A4 (wt%) 48.33 0.43 17.04 7.80 14.58 10.80 1.78 0.95 0.13

Mixing: DM05-212A (mol%) 39.01 0.27 4.05 10.98 40.39 3.80 1.19 0.26 0.05 92.46 78.63 84.01 94.60

With: DM05-212C (mol%) 51.64 0.34 12.37 4.36 13.95 14.62 1.93 0.73 0.06 91.42 76.17 82.04 93.84

Producing: Model Composition (mol%) 48.03 0.32 9.99 6.25 21.50 11.53 1.72 0.60 0.06 91.98 77.47 83.09 94.24

Matching: KF07-A4 (mol%) 47.20 0.34 10.27 6.93 21.69 11.20 1.39 0.90 0.07 91.25 75.78 81.72 93.71

Figure A6- 5. Results of crystallization modeling for the Conuma River samples. Two samples: DM05-212A=olivine hornblendite and DM05-212C=hornblende gabbro mix in the ratio 1 : 2.5 retrospectively, producing a model, whose composition is close to a composition of hornblende gabbro sheet containing hornblende megacrysts (KF07-A4). This sample displays in the field a mingling process involving olivine hornblendite and hornblende gabbro. Successful mixing shows model curve (Model Unconstrained), closely matching a sample curve (KF07-A4).

234


Model Unc 0.77 1.46 1.11 1.85 5.38 2.30 0.59 0.72 0.81

KF08-10 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

KF07-F1 0.75 1.49 1.12 1.85 5.46 2.44 0.74 0.46 1.00

0.10

1.00

10.00U

nco

nstr

ain

ed

Cu

rves:

Mix

ing

to

nali

te w

ith

ho

rnb

len

de g

ab

bro

Magma Mixing for Conuma River tonalite and hornblende gabbro


Model

Unc

KF08-10

KF07-F1


Total Gains (molecular %) 250 (mixing 1 part of KF08-10 with 2.5 parts of DM05-212C)

Magnetite (8 %TiO2) 3.80%

Magma or rock 96.20%


/Fe2+

) = 0.3 Samples SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in

Mixing: KF08-10 (wt%) 67.50 0.48 16.00 3.88 1.16 4.27 4.13 1.66 0.17 equilibr. equilibr.

With: KF05-212C (wt%) 47.52 0.42 19.32 4.80 8.61 12.55 1.83 1.06 0.13 olivine Fe3+

/Fe 2+

olivine

Producing: Model composition (wt%) 53.25 0.71 18.30 7.37 6.40 10.09 2.50 1.23 0.14 0%Fe3+

0%Fe3+

0.30 0.30

Matching: KF07-F1 (wt%) 50.85 0.71 17.91 7.20 6.35 10.44 3.05 0.77 0.17

Mixing: KF08-10 (mol%) 73.39 0.39 10.25 3.53 1.88 4.98 4.35 1.15 0.08 63.98 34.76 43.22 71.73

With: KF05-212C (mol%) 51.64 0.34 12.37 4.36 13.95 14.62 1.93 0.73 0.06 91.42 76.17 82.04 93.84

Producing: Model composition (mol%) 56.44 0.57 11.42 6.53 10.12 11.46 2.57 0.83 0.06 83.77 60.77 68.87 88.06

Matching: KF07-F1 (mol%) 55.19 0.58 11.45 6.54 10.27 12.15 3.21 0.53 0.08 83.97 61.12 69.19 88.22

Figure A6- 6. Results of crystallization modeling for the Conuma River samples. Two samples KF08-10=tonalite and DM05-212C=hornblende gabbro mix in the ratio 1 : 2.5 retrospectively, producing a model, whose composition is close to a composition of spotted hornblende gabbro (KF07-F1), displaying in the field mingling process involving tonalite and hornblende gabbro. Successful mixing can be performed if model curve (Model Unconstrained) matches a sample curve (KF07-F1). To get a match, in this case, addition of 3.8% magnetite with 8 wt% TiO2, at the ratio magnetite:hornblende gabbro magma 3.8 : 96.2 was necessary and it is difficult to explain it in geological means.

235


Model Unc 0.75 0.86 0.87 1.78 9.97 1.57 0.57 0.62 0.78

Parental 1 1 1 1 1 1 1 1 1

KF08-10 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

KF07-R2 0.82 0.87 0.56 1.64 9.55 1.50 0.47 0.41 0.31

0.10

1.00

10.00

Un

co

nstr

ain

ed

Cu

rves:

Mix

ing

to

nali

te, h

orn

ble

nd

ite a

nd

ho

rnb

len

de g

ab

bro

Magma Mixing for Conuma River tonalite, hornblendite and hornblende gabbro


Model Unc

Parental

KF08-10

KF07-R2


Total Gains (molecular %) 200 (mixing 1 part of KF08-10 with 2 parts of DM05-212C and DM05-212A)

Magma or rock (DM05-212C) 50%

Magma or rock (DM05-212A) 50%


/Fe2+


Mixing: KF08-10 (wt%) 67.50 0.48 16.00 3.88 1.16 4.27 4.13 1.66 0.17 equilibr. equilibr.

With: DM05-212C (wt%) 47.52 0.42 19.32 4.80 8.61 12.55 1.83 1.06 0.13 olivine Fe3+

/Fe 2+olivine

And With: DM05-212A (wt%) 39.52 0.36 6.97 13.30 27.45 3.59 1.24 0.42 0.11 0%Fe3+

0%Fe3+

0.3 0.3

Producing: Model Composition (wt%) 53.92 0.44 14.88 7.42 12.40 7.17 2.53 1.11 0.14

Matching: KF07-R2 (wt%) 58.57 0.44 9.41 7.20 11.72 6.78 2.07 0.72 0.06

Mixing: KF08-10 (mol%) 73.39 0.39 10.25 3.53 1.88 4.98 4.35 1.15 0.08 63.98 34.76 43.22 71.73

With: DM05-212C (mol%) 51.64 0.34 12.37 4.36 13.95 14.62 1.93 0.73 0.06 91.42 76.17 82.04 93.84

And With: DM05-212A (mol%) 39.01 0.27 4.05 10.98 40.39 3.80 1.19 0.26 0.05 92.46 78.63 84.01 94.60

Producing: Model Composition (mol%) 54.68 0.33 8.89 6.29 18.74 7.80 2.49 0.72 0.06 90.85 74.87 80.97 93.42

Matching: KF07-R2 (mol%) 60.19 0.34 5.70 5.78 17.96 7.47 2.06 0.47 0.02 91.19 75.63 81.60 93.66

Figure A6- 7. Results of crystallization modeling for the Conuma River samples. Three samples mix at the ratio 1 : 1 : 1 (KF08-10=tonalite : DM05-212C=hornblende gabbro: DM05-212A=olivine hornblendite, producing a model, whose composition is fairly close to a composition of KF07-R2=hornblende diorite. Successful mixing can be performed if model curve (Model Unconstrained) matches a sample curve (07-R2). This model represents the closest possible match. This mixing is likely, but there is no clear direct evidence in the field or in thin section for such mixing.

236


Parental: KF07-P 1 1 1 1 1 1 1 1 1

Model 1.67 1.30 2.39 1.69 2.15 2.60 1.41 1.00 1.55

DM05-212C 1.62 1.27 2.40 1.25 2.07 2.60 1.38 1.38 1.48

0.1

1

10

Co

ns

tra

ine

d C

urv

es

:

No

rma

lize

d to

po

ss

ible

pa

ren

tal

ga

bb

ro (

KF

07

-P)

Mineral Accumulation for Conuma River hornblende gabbro

Constrained by Ce

Parental:

KF07-P

Model

DM05-212C

A


Parental: KF07-P 1 1 1 1 1 1 1 1 1

Model 1.67 1.30 2.39 1.22 2.15 2.60 1.41 1.00 1.55

DM05-212C 1.62 1.27 2.40 1.25 2.07 2.60 1.38 1.38 1.48

0.1

1

10

Co

ns

tra

ine

d C

urv

es

:

No

rma

lize

d to

po

ss

ible

pa

ren

tal

ga

bb

ro (

KF

07

-P)

Mineral Accumulation and Fractionation for Conuma River hornblende gabbro

Constrained by Ce

Parental:

KF07-P

Model

DM05-212C

B






/Fe2+

) = 0.3 Orthopyroxene (En%) 85 0


Apatite 0.20

Modeling LOSSES

Expected bulk partition coefficient (D)

of "conserved" element: Ce 0.217

Total Losses (molecular %)

Magnetite (0.0001 wt%TiO2) 3


/Fe2+



DM05-212C (wt%) 47.52 0.42 19.32 4.80 8.61 12.55 1.83 1.06 0.13 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

KF07-P (mol%) 57.87 0.49 9.32 6.35 12.23 10.18 2.53 0.97 0.07 86.53 65.84 73.36 90.18

DM05-212C (mol%) 51.64 0.34 12.37 4.36 13.95 14.62 1.93 0.73 0.06 91.42 76.17 82.04 93.84




DM05-212C (wt%) 47.52 0.42 19.32 4.80 8.61 12.55 1.83 1.06 0.13 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

KF07-P (mol%) 57.87 0.49 9.32 6.35 12.23 10.18 2.53 0.97 0.07 86.53 65.84 73.36 90.18

DM05-212C (mol%) 51.64 0.34 12.37 4.36 13.95 14.62 1.93 0.73 0.06 91.42 76.17 82.04 93.84


Figure A6- 8. Results of crystallization modeling for the Conuma River samples. A: Parental sample (KF07-P=non-cumulate plagioclase phyric, quartz-hornblende gabbro) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (DM05-212C=hornblende gabbro) are rationed. It is difficult to achieve a match with the evolved sample by a simple accumulation. B: The match can be achieved by a combination of A and B, which means that accumulation of augite, plagioclase, olivine, magnetite and apatite (from A) needs to be combined with fractionation of 3% magnetite (from B). This is difficult to explain geologically, therefore this model is shown as an example of a complex processes that cannot by explained by a simple fractionation or accumulation. As the model fails to relate parental hornblende gabbro to a variety of hornblende gabbro sheet, their relationship is uncertain.

237


Parental:

KF07-P1 1 1 1 1 1 1 1 1

Model 1.23 1.61 1.70 1.50 1.15 1.51 1.37 1.00 1.35

KF07-F1 1.25 1.55 1.61 1.35 1.10 1.56 1.66 0.72 1.39

0.1

1

10

Co

ns

tra

ine

d C

urv

es

:

No

rma

lize

d to

po

ss

ible

pa

ren

tal

ga

bb

ro (

KF

07

-P)

Mineral Accumulation for Conuma River hornblende gabbro/diorite

Constrained by Ce

Parental:

KF07-P

Model

KF07-F1

A


Parental:

KF07-P1 1 1 1 1 1 1 1 1

Model 0.92 1.00 1.00 0.86 0.71 0.83 1.00 1.00 1.00

KF07-D5 1.05 1.23 1.17 1.74 0.71 0.84 1.33 1.02 1.60

0.1

1

10

Co

ns

tra

ine

d C

urv

es

:

No

rma

lize

d to

po

ss

ible

pa

ren

tal

ga

bb

ro (

KF

07

-P)

Mineral Fractionation for Conuma River hornblende diorite

Constrained by Ce

Parental:

KF07-P

Model

KF07-D5

B



of "conserved" element: Ce 0.201 Olivine (Fo%) 80 0



/Fe2+



Apatite 0.40

Modeling LOSSES Fractionating Phases Mineral Composition Recalculated % of Phases

Expected bulk partition coefficient (D) Plagioclase (An%) 75 0


Total Losses (molecular %) 11 Augite (Di%) 80 61.90


/Fe2+


Magnetite (%TiO2) 10 0

Apatite 0 Samples SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in


KF07-F1 (wt%) 50.85 0.71 17.91 7.20 6.35 10.44 3.05 0.77 0.17 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

KF07-P (mol%) 57.87 0.49 9.32 6.35 12.23 10.18 2.53 0.97 0.07 86.53 65.84 73.36 90.18

KF07-F1 (mol%) 55.19 0.58 11.45 6.54 10.27 12.15 3.21 0.53 0.08 83.97 61.12 69.19 88.22




KF07-D5 (wt%) 55.00 0.72 16.65 11.90 5.22 7.18 3.13 1.40 0.25 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

KF07-P (mol%) 57.87 0.49 9.32 6.35 12.23 10.18 2.53 0.97 0.07 86.53 65.84 73.36 90.18

KF07-D5 (mol%) 58.01 0.57 10.35 10.50 8.21 8.12 3.20 0.94 0.11 72.27 43.88 52.76 78.83


Figure A6- 9. Results of crystallization modeling for the Conuma River samples. Parental sample (KF07-P=non-cumulate plagioclase phyric, quartz-hornblende gabbro) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition KF07-F1=spotted hornblende gabbro/diorite in A and KF07-D5=mafic enclave of hornblende diorite in B are rationed. It is difficult to achieve a match with the evolved sample by a simple accumulation in A. It is also difficult to achieve a match with the evolved sample in B as it requires accumulation and fractionation of some phases simultaneously. Both examples show that more complex processes behind the formation of these intrusive varieties and cannot be explained by a simple fractionation or accumulation and their relationship to the parent is uncertain.

238


Parental: KF07-P 1 1 1 1 1 1 1 1 1

Model 0.74 1.00 1.00 0.55 0.18 0.57 1.00 1.00 1.00

KF08-10 1.59 0.99 1.37 0.69 0.19 0.61 2.15 1.49 1.33

0.01

0.1

1

10C

on

str

ain

ed

Cu

rves:

No

rmali

zed

to

po

ssib

le p

are

nta

l g

ab

bro

(K

F07-P

)

Mineral Fractionation for Conuma River hornblende gabbro and tonalite

Constrained by Ce

Parental:

KF07-P

Model

KF08-10




Total Losses (molecular %) 32 Augite (Di%) 78 70


/Fe2+


Magnetite (%TiO2) 7 0 Samples SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in


KF08-10 (wt%) 67.50 0.48 16.00 3.88 1.16 4.27 4.13 1.66 0.17 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

Parent: KF07-P (mol%) 57.87 0.49 9.32 6.35 12.23 10.18 2.53 0.97 0.07 86.53 65.84 73.36 90.18

KF08-10 (mol%) 73.39 0.39 10.25 3.53 1.88 4.98 4.35 1.15 0.08 63.98 34.76 43.22 71.73


Figure A6- 10. Results of crystallization modeling for the Conuma River samples. Parental sample (KF07-P=non-cumulate, plagioclase phyric, quartz-hornblende gabbro) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (KF8-10=tonalite) are normalized. It is difficult to achieve a match with the evolved sample by simple fractionation. The match can be achieved by combination of accumulation and fractionation (not shown here), which is difficult to explain geologically. As the model fails to relate parental hornblende gabbro to tonalite, their relationship is uncertain.

239


Parental:

DM06-381 1 1 1 1 1 1 1 1

Model 0.85 1.00 1.00 0.83 0.20 0.64 1.00 1.00 0.48

KF08-52B 1.73 0.45 1.05 0.83 0.20 0.69 1.46 0.38 0.46

0.01

0.1

1

10C

on

str

ain

ed

Cu

rve

s:

No

rma

lize

d to

po

ss

ible

pa

ren

tal

ga

bb

ro (

DM

06

-38

)

Mineral Fractionation for Leagh Creek hornblende gabbro and tonalite

Constrained by Ce

Parental:

DM06-38

Model

KF08-52B

Modeling LOSSES Fractionating Phases Mineral CompositionRecalculated % of Phases





/Fe2+




Parent: DM06-38 (wt%) 50.02 1.09 18.02 9.07 5.37 7.06 4.13 1.40 0.35 equilibr. equilibr.

KF08-52B(wt%) 69.58 0.39 15.15 6.06 0.88 3.94 4.84 0.43 0.13 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

Parent: DM06-38 (mol%) 55.79 0.91 11.84 8.46 8.93 8.44 4.46 1.00 0.17 77.86 51.35 60.12 83.40

KF08-52B(mol%) 73.69 0.31 9.45 5.37 1.39 4.47 4.97 0.29 0.06 46.32 20.56 26.99 55.21


Figure A6- 11. Results of crystallization modeling for the Leagh Creek samples. Parental sample (DM06-38=non-cumulate hornblende gabbro) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (KF08-52B=tonalite) are rationed. It is difficult to achieve a match with the evolved sample by simple fractionation. The match can be achieved by combination of accumulation and fractionation (not shown here), which is difficult to explain geologically. As the model fails to relate parental hornblende gabbro to tonalite, their relationship is uncertain.

240


Parental: KF08-

52B1 1 1 1 1 1 1 1 1

Model 0.86 0.25 0.51 0.33 0.22 0.18 0.77 1.00 0.27

KF08-52A 0.72 0.25 0.54 0.33 0.22 0.18 0.52 5.20 0.25

0.1

1

10

Co

nstr

ain

ed

Cu

rves:

No

rmali

zed

to

po

ssib

le p

are

nta

l to

nali

te (

KF

08-5

2B

)

Mineral Fractionation for Leagh Creek tonalite and trondhjemite

Constrained by Ce Parental:

KF08-52B

Model

KF08-52A

Modeling LOSSES Fractionating Phases Mineral CompositionRecalculated % of Phases





/Fe2+


Magnetite (%TiO2) 7.5 12.50

Apatite 0.70 Samples SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in Parent: KF08-52B (wt%) 69.58 0.39 15.15 6.06 0.88 3.94 4.84 0.43 0.13 equilibr. equilibr.

KF08-52A (wt%) 76.10 0.15 12.35 3.07 0.30 1.10 3.80 3.39 0.05 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

Parent: KF08-52B (mol%) 73.69 0.31 9.45 5.37 1.39 4.47 4.97 0.29 0.06 46.32 20.56 26.99 55.21

KF08-52A (wt%) 81.35 0.12 7.78 2.74 0.48 1.26 3.94 2.31 0.02 36.73 14.83 19.92 45.34


Figure A6- 12. Results of crystallization modeling for the Leagh Creek samples. Parental sample (KF08-52B=tonalite) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (KF08-52A= trondhjemite) are rationed. It is difficult to achieve a perfect match with the evolved sample by simple fractionation. A fairly close match can be achieved by fractionation plagioclase>augite>magnetite and apatite. It suggests that tonalite and trondhjemite can be genetically related.

241


Parental: basalt-47 1 1 1 1 1 1 1 1 1

Model 0.71 1.00 0.26 0.74 0.44 0.56 0.05 1.00 1.00

basaltic andesite-90 0.29 0.21 0.28 0.23 0.11 0.17 0.41 0.46 0.31

0.1

1

Co

nstr

ain

ed

Cu

rves:

No

rmali

zed

to

po

ssib

le p

are

nta

l b

asalt

(47)

Hornblende Fractionation for Port Renfrew basalt and basaltic andesite

Constrained by Ce

Parental: basalt-47

Model

basaltic andesite-90

A


Parental: basalt-47 1 1 1 1 1 1 1 1 1

Model 0.49 0.43 0.37 0.30 0.14 0.22 0.80 1.00 0.39

Basaltic andesite-90 0.38 0.27 0.37 0.29 0.14 0.22 0.52 0.59 0.40

0.1

1

Co

nstr

ain

ed

Cu

rves:

No

rmali

zed

to

po

ssib

le p

are

nta

l b

asalt

(47)

Mineral Fractionation for Port Renfrew basalt and basaltic andesite

Constrained by Ce

Parental: basalt-47

Model

Basaltic andesite-90

B

Modeling LOSSES Fractionating Phases Mineral Composition Recalculated % of Phases Expected bulk partition coefficient (D) Plagioclase (An%) 85 0


Total Losses (molecular %) 40 Augite (Di%) 80 0


/Fe2+



Apatite 0

Amphibole (%Fe in Pargasite) 25 100




Total Losses (molecular %) 60.5 Augite (Di%) 80 37.92


/Fe2+



Apatite 0.50

Samples SiO2 TiO2 Al2O3 FeO* MgO CaO Na2O K2O P2O5 Fo% in Mg# Mg# Fo% in Parent: basalt-47 (wt%) 48.28 1.05 16.13 10.65 8.42 9.89 2.54 1.17 0.23 equilibr. equilibr.

basaltic andesite-90 (wt%) 53.52 0.84 17.35 9.06 3.38 6.21 3.89 2.03 0.27 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.20 0.20

Parent: basalt-47 (mol%) 51.40 0.84 10.12 9.48 13.36 11.29 2.62 0.79 0.10 82.45 58.49 66.81 87.03

basaltic andesite-90 (mol%) 60.25 0.71 11.51 8.53 5.67 7.49 4.24 1.46 0.13 68.91 39.94 48.72 76.00



Parent: basalt-47 (wt%) 48.28 1.05 16.13 10.65 8.42 9.89 2.54 1.17 0.23 equilibr. equilibr.

basaltic andesite-90 (wt%) 53.52 0.84 17.35 9.06 3.38 6.21 3.89 2.03 0.27 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.20 0.20


basaltic andesite-90 (mol%) 60.25 0.71 11.51 8.53 5.67 7.49 4.24 1.46 0.13 68.91 39.94 48.72 76.00


Figure A6- 13. Results of crystallization modeling for the Port Renfrew samples (data from Larocque 2008). Parental sample (Port Renfrew basalt- 47) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (Port Renfrew basaltic andesite-90) are normalized. A: It is difficult to achieve a match for constrained conditions by 40% hornblende fractionation as suggested by Larocque (2008). B: The same samples can be linked with a partial match by simple 61% fractionation of augite>plagioclase> orthopyroxene>magnetite>olivine and apatite.

242


Parental: basalt-47 1 1 1 1 1 1 1 1 1

Model 1.66 1.00 2.67 1.59 2.26 2.00 3.15 1.00 1.00

olivine cumulate-43 9.70 4.01 2.50 24.11 43.69 2.70 1.66 1.80 2.70

0.1

1

10

100

Co

nstr

ain

ed

Cu

rves:

No

rmali

zed

to

po

ssib

le p

are

nta

l b

asalt

(47)

Hornblende Accumulation for Port Renfrew basalt and olivine cumulate

Constrained by Ce

Parental: basalt-

47

Model

olivine cumulate-

43

A


Parental: basalt-47 1 1 1 1 1 1 1 1 1

Model 4.46 1.68 1.12 10.28 18.27 1.13 1.04 1.00 1.21

olivine cumulate-43 4.23 1.75 1.09 10.51 19.05 1.18 0.72 0.79 1.18

0.1

1

10

100

Co

nstr

ain

ed

Cu

rves:

No

rmali

zed

to

po

ssib

le p

are

nta

l b

asalt

(47)

Mineral Accumulation for Port Renfrew basalt and olivine cumulate

Constrained by Ce

Parental:

basalt-47

Model

olivine

cumulate-43

B

Modeling GAINS Fractionating Phases Mineral CompositionRecalculated % of Phases


of "conserved" element:Ce 0.34 Olivine (Fo%) 85 0

Total Gains (molecular %) 90 Augite (Di%) 80 0


/Fe2+

) =0.3 Orthopyroxene (En%) 85 0

Magnetite (%TiO2) 1.2 0

Amphibole (%Fe) 25 100






/Fe2+





olivine cumulate-43 (wt%) 37.78 0.34 3.25 20.71 29.67 2.15 0.34 0.17 0.05 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30


olivine cumulate-43 (mol%) 36.24 0.25 1.84 16.61 42.42 2.21 0.32 0.10 0.02 89.49 71.86 78.49 92.40




olivine cumulate-43 (wt%) 37.78 0.34 3.25 20.71 29.67 2.15 0.34 0.17 0.05 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30


olivine cumulate-43 (mol%) 36.24 0.25 1.84 16.61 42.42 2.21 0.32 0.10 0.02 89.49 71.86 78.49 92.40


Figure A6- 14. Results of crystallization modeling for the Port Renfrew samples (data from Larocque 2008). A: Parental sample (Port Renfrew basalt-47) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (Port Renfrew olivine cumulate-43) are rationed. The samples cannot be related by accumulation of any amount of hornblende. B: The same samples can be related by accumulation of olivine>orthopyroxene>magnetite>plagioclase-augite and apatite.

243


Parental: basalt-47 1 1 1 1 1 1 1 1 1

Model 3.74 6.14 5.40 6.15 3.49 6.60 2.89 1.00 1.41

plagioclase

cumulate-93.96 6.09 5.24 6.25 3.54 5.55 2.73 1.52 1.35

0.1

1

10

Co

nstr

ain

ed

Cu

rves:

No

rmali

zed

to

po

ssib

le p

are

nta

l b

asalt

(47)

Mineral Accumulation for Port Renfrew basalt and plagioclase cumulate

Constrained by Ce

Parental:

basalt-47

Model

plagioclase

cumulate-9






/Fe2+





plagioclase cumulate-9 (wt%) 43.03 1.44 19.05 15.00 6.72 12.36 1.56 0.40 0.07 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

Parent: basalt-47(mol%) 51.40 0.84 10.12 9.48 13.36 11.29 2.62 0.79 0.10 82.45 58.49 66.81 87.03

plagioclase cumulate-9 (mol%) 46.30 1.17 12.07 13.50 10.78 14.25 1.63 0.27 0.03 72.69 44.40 53.29 79.18


Figure A6- 15. Results of crystallization modeling for the Port Renfrew samples (data from Larocque 2008). A: Parental sample (Port Renfrew basalt-47) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (Port Renfrew plagioclase cumulate-9) are rationed. A fairly good match can be achieved through a simple accumulation of augite>plagioclase>magnetite and minor apatite.

244


Parental: gabbro-91-43A 1 1 1 1 1 1 1 1 1

Model 2.21 2.73 2.93 2.72 2.35 3.56 1.73 1.00 1.00

gabbro-91-17 2.28 2.82 2.80 2.68 2.27 3.56 1.42 1.73 0.79

0.1

1

10

Co

ns

tra

ine

d C

urv

es

:

No

rma

lize

d to

po

ss

ible

pa

ren

tal

ga

bb

ro (

91

-43

A)

Mineral Accumulation for Broken Islands gabbros

Constrained by Zr

Parental:

gabbro-91-43A

Model

gabbro-91-17



of "conserved" element: Zr 0.169 Olivine (Fo%) 85 0



/Fe2+




Parent: gabbro-91-43A (wt%) 49.10 0.90 17.90 11.86 7.26 9.83 2.32 0.58 0.19 equilibr. equilibr.

gabbro-91-17 (wt%) 44.60 1.01 20.00 12.67 6.57 13.94 1.31 0.40 0.06 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

Parent: gabbro-91-43A (mol%) 52.07 0.72 11.18 10.52 11.48 11.17 2.38 0.39 0.09 78.43 52.18 60.92 83.86

gabbro-91-17 (mol%) 47.43 0.81 12.53 11.27 10.42 15.89 1.35 0.27 0.03 75.50 48.03 56.90 81.49


Figure A6- 16. Results of crystallization modeling for the Broken Islands samples (data from DeBari et al. 1999). Parental sample (91-43A=gabbro) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (91-17=gabbro) are rationed. It is difficult to achieve a perfect match with the evolved sample. The plot suggests that these gabbros can are related by 145% accumulation of augite>plagioclase>magnetite>orthopyroxene. The model composition and amount and type of phases needed in the accumulation process resemble just another gabbro variety, whose geochemistry and mode is overlapping with gabbros occurring in the Bonanza arc (geochemistry and modes available in DeBari et al. 1999).

245


Parental mafic dyke 1728A3 1 1 1 1 1 1 1 1 1

Model 0.84 1.00 0.60 0.84 0.76 0.75 0.94 1.00 1.00

chilled mafic 1719A4 0.44 0.54 0.38 0.46 0.37 0.38 0.65 0.37 0.66

0.1

1

Co

ns

tra

ine

d C

urv

es:

No

rma

lized

to

pa

ren

tal m

afi

c d

yk

e (

17

28

A3

)

Mineral Fractionationfor Talkeetna mafic dyke and chilled mafic

Constrained by Ce

Parental mafic dyke

1728A3

Model

chilled mafic 1719A4

A


Parental: mafic dyke 1728A3 1 1 1 1 1 1 1 1 1

Model 0.59 0.55 0.39 0.46 0.38 0.39 0.59 1.00 0.67

chilled mafic 1719A4 0.44 0.55 0.39 0.46 0.37 0.38 0.66 0.37 0.66

0.1

1

Co

nstr

ain

ed

Cu

rves:

No

rmalized

to

p

are

nta

l mafi

c d

yke (

1728A

3)

Mineral Fractionationfor Talkeetna mafic dyke and chilled mafic

Constrained by Ce

Parental: mafic dyke 1728A3

Model

chilled mafic 1719A4

B



of "conserved" element: Ce 0.21128 Augite (Di%) 80 42.90

Total Losses (molecular %) 20.7 Orthopyroxene (En%) 81 8.00


/Fe2+

) = 0.3 Mg-Al spinel 17.50






/Fe2+



Apatite 0.10


Parent: mafic dyke 1728A3 (wt%) 48.06 0.59 19.26 8.86 8.09 11.96 1.42 0.43 0.07 equilibr. equilibr.

chilled mafic 1719A4 (wt%) 49.99 0.76 17.64 9.62 7.16 10.84 2.20 0.38 0.11 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

Parent: mafic dyke 1728A3 (mol%) 51.23 0.47 12.09 7.90 12.85 13.66 1.47 0.29 0.03 84.436 61.94 69.9252 88.5716

chilled mafic 1719A4 (mol%) 53.34 0.61 11.09 8.58 11.39 12.40 2.28 0.26 0.05 81.557 57.02 65.46 86.3338



Parent: mafic dyke 1728A3 (wt%) 48.06 0.59 19.26 8.86 8.09 11.96 1.42 0.43 0.07 equilibr. equilibr.

chilled mafic 1719A4 (wt%) 49.99 0.76 17.64 9.62 7.16 10.84 2.20 0.38 0.11 olivine Fe3+

/Fe2+

olivine


0%Fe3+

0.30 0.30

Parent: mafic dyke 1728A3 (mol%) 51.23 0.47 12.09 7.90 12.85 13.66 1.47 0.29 0.03 84.436 61.94 69.9252 88.5716

chilled mafic 1719A4 (mol%) 53.34 0.61 11.09 8.58 11.39 12.40 2.28 0.26 0.05 81.557 57.02 65.46 86.3338


Figure A6- 17. Results of crystallization modeling for the Talkeetna arc samples (data from Greene et al. 2006). A: Parental sample (mafic dyke-1728A3) is plotted on the graph as a horizontal line with composition 1, to which model liquid composition and evolved sample composition (chilled mafic-1719A4) are rationed. It is difficult to relate these samples through constrained conditions by suggested 20.7% of fractionation and involved fractionating phases: 42.9% clinopyroxene, 31.6% plagioclase, 8% orthopyroxene and 17.5% Mg-Al spinel (Greene et al. 2006). B: Not a perfect fit, but a better fit than in A can be achieved through constrained conditions by 50% fractionation of augite=plagioclase>olivine>magnetite>orthopyroxene and apatite.

karin fecova msc thesis 2009 for binding

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