wong, 2011 (b.sc.g.sc.hons.thesis-final).compressed

Lithofacies Analysis and Stratigraphic Correlation of the Upper Ordovician Red

Head Rapids Formation, Hudson Bay Basin, Northeastern Manitoba

By

May E. Wong

A Thesis submitted to the Department of Geological Sciences of

The University of Manitoba

in partial fulfilment of the requirements of the degree of

BACHELOR OF SCIENCE

IN GEOLOGICAL SCIENCES (HONOURS)

Department of Geological Sciences

University of Manitoba

Winnipeg

April 2011

i

ABSTRACT As part of the Geo-mapping for Energy and Minerals program, initiated

by the Geological Survey of Canada, the Upper Ordovician Red Head Rapids

Formation in the Hudson Bay Basin is being evaluated as a potential petroleum

source rock. Cores from the Houston Oils et al. Comeault STH No. 1 and

Sogepet-Aquitaine Kaskattama Province No. 1 wells located in the Hudson Bay

Lowland, northeastern Manitoba, were examined and analyzed as part of this

study. Representative samples were studied in detail using thin section

petrography, and selected samples from the greyish-green dolomudstone units

were further analyzed using organic geochemistry and X-ray diffraction.

The Red Head Rapids Formation (32-41.9 m thick) in the study area is

composed of mostly dolomudstones with intervals of evaporite rocks. Six

lithofacies are recognized: A) greyish-green dolomudstone, B) skeletal

wackestone, C) mottled-nodular lime mudstone, D) massive-laminated

dolomudstone, E) interlaminated dolomudstone, anhydrite and halite, and F)

anhydrite. These lithofacies are grouped into three lithofacies associations: 1)

open subtidal, 2) saline subtidal and 3) saline mud flat.

The Red Head Rapids Formation in the study area comprises four

meter-scale, shallowing and brining-upward carbonate-evaporite cycles. The

open subtidal lithofacies association, overlain by the saline subtidal lithofacies

association and capped by the saline mud flat lithofacies association form a

transgressive-regressive cycle in response to sea-level fluctuations. From the

ii

correlation of the lithofacies associations between the Comeault No. 1 and

Kaskattama No. 1 wells, the tidal flat island model is proposed to explain the

shallowing-upward cycles and laterally discontinuous lithofacies in the study

area. Comparison of the cycles in these wells to those recognized in the Red

Head Rapids Formation in the offshore Polar Bear C-11 well and in outcrops at

Cape Donovan, Southampton Island suggests that the study area during the

Late Ordovician was in a basin-margin position, based on the abundance of

peritidal lithofacies and the absence of organic-rich lithofacies and argillaceous

lithofacies. Southampton Island is interpreted to have been situated in a basin-

central position, based on the presence of oil shales and argillaceous rocks.

Based on limited Rock Eval™ 6/total organic carbon results, lithofacies

A (greyish-green dolomudstone) in the study area appears to have low source

rock potential. Controlling factors are poor productivity and/or poor

preservation of organic matter and insufficient burial conditions.

iii

ACKNOWLEDGEMENTS

First I would like to thank my thesis advisors, Dr. Nancy Chow and

Ms. Michelle Nicolas. Dr. Chow and Ms. Nicolas were tremendously

supportive and helpful throughout this project. I am heartily thankful for

Dr. Chow’s supervision and support which has enabled me to gain a

better understanding in the subject. I would also like to extend my thanks

to Dr. Ian Ferguson for being the thesis coordinator.

I would also like to thank Dr. Denis Lavoie from the Geological

Survey of Canada for funding and supporting this project. Thanks also to

Mr. Gerry Benger, Mr. Rick Unruh and Mr. Vioŕel Varga from the Midland

Core Storage Facility for their assistance while I was examining cores.

I am grateful to all the staff in the Department of Geological

Sciences at the University of Manitoba for providing a stimulating and fun

environment to learn and grow. Special thanks to the technical staff, Mr.

Neil Ball and Ms. Ravinder Sidhu for helping me with the laboratory

equipment. Thanks also to Dr. Bob Elias for providing his insights.

Finally, I am indebted to my family and friends for their unceasing

encouragement and support during my university career.

iv 1 1

TABLE OF CONTENTS

ABSTRACT........................................................................................................i

ACKNOWLEDGEMENTS................................................................................iii

TABLE OF CONTENTS...................................................................................iv

LIST OF FIGURES...........................................................................................vi

LIST OF TABLES ...........................................................................................vii

LIST OF APPENDICES ..................................................................................vii

CHAPTER 1: INTRODUCTION .........................................................................1 1.1 Prologue............................................................................................................. 1 1.2 Geological Setting............................................................................................. 2 1.3 Previous Work ................................................................................................... 4 1.4 This Study.......................................................................................................... 5

1.4.1 Study Area.................................................................................................... 5 1.4.2 Objectives..................................................................................................... 7

1.5 Methodology ...................................................................................................... 7 1.5.1 Core Examination......................................................................................... 7 1.5.2 Thin Section Petrography............................................................................. 8 1.5.3 X-ray Diffraction............................................................................................ 8 1.5.4 Rock Eval™ 6............................................................................................... 9 1.5.4 Datum........................................................................................................... 9

CHAPTER 2: STRATIGRAPHY.......................................................................10 2.1 Regional Stratigraphy ..................................................................................... 10 2.2 Upper Ordovician in the Hudson Bay Lowland............................................ 10 2.3 Stratigraphy of the Red Head Rapids Formation in the Study Area........... 11

CHAPTER 3: LITHOFACIES ANALYSIS........................................................14 3.1 Introduction ..................................................................................................... 14 3.2 Lithofacies A: Greyish-Green Dolomudstone .............................................. 14

3.2.1 Description ................................................................................................. 14 2.2.2 Interpretation .............................................................................................. 23

3.3 Lithofacies B: Skeletal Wackestone .............................................................. 23 3.3.1 Description ................................................................................................. 23 3.3.2 Interpretation .............................................................................................. 25

3.4 Lithofacies C: Mottled-Nodular Skeletal Lime Mudstone ............................ 27 3.4.1 Description ................................................................................................. 27 3.4.2 Interpretation .............................................................................................. 27

3.5 Lithofacies D: Massive-Laminated Dolomudstone ...................................... 30 3.5.1 Description ................................................................................................. 30 3.5.2 Interpretation .............................................................................................. 33

3.6 Lithofacies E: Interlaminated Dolomudstone, Anhydrite and Halite .......... 33 3.6.1 Description ................................................................................................. 33 3.6.2 Interpretation .............................................................................................. 35

3.7 Lithofacies F: Anhydrite ................................................................................. 37

v 1 1

3.7.1 Description ................................................................................................. 37 3.7.2 Interpretation .............................................................................................. 40

CHAPTER 4: LITHOFACIES ASSOCIATIONS AND METER-SCALE CYCLICITY.......................................................................................................41

4.1 Lithofacies Associations ................................................................................ 41 4.2 Meter-Scale Cyclicity ...................................................................................... 42 4.3 Correlation of Meter-Scale Cycles ................................................................. 45

CHAPTER 5: STRATIGRAPHIC CORRELATION..........................................49 5.1 Introduction ..................................................................................................... 49 5.2 Correlation Between Comeault No. 1, Kaskattama No. 1 And Polar Bear C-11 Wells .................................................................................................................. 49 5.3 Correlation with the Cape Donovan Outcrop, Southampton Island........... 52

CHAPTER 6: ORGANIC GEOCHEMISTRY....................................................54 6.1 Introduction ..................................................................................................... 54 6.2 Results For Total Organic Carbon (TOC), Maximum Temperature (Tmax) and Production Index (PI) ............................................................................................ 55 6.3 Hydrogen Index-Oxygen Index (HI-OI) Plot................................................... 56 6.4 Comparison to the Red Head Rapids Formation, Cape Donovan, Southamption Island............................................................................................. 58

CHAPTER 7: DISCUSSION.............................................................................60 7.1 Introduction ..................................................................................................... 60 7.2 Tidal Flat Island Model.................................................................................... 67 7.3 Paleogeography of the Hudson Bay Basin................................................... 64 7.4 Petroleum Source Rock Potential ................................................................. 64 7.5 Future Work ..................................................................................................... 65

CHAPTER 8: CONCLUSION...........................................................................67

REFERENCES.................................................................................................69

vi

LIST OF FIGURES

Figure 1.1. Geological setting of the Hudson Bay Basin ................................... 3

Figure 1.2.Geologic map of the Hudson Bay Lowland ...................................... 6

Figure 2.1. Stratigraphy of the Hudson Bay Lowland ...................................... 12

Figure 3.1. Lithofacies A: greyish-green dolomudstone .................................. 21

Figure 3.2. Lithofacies A: greyish-green dolomudstone .................................. 22

Figure 3.3. Lithofacies B: skeletal wackestone................................................ 24

Figure 3.4. Lithofacies B: skeletal wackestone................................................ 26

Figure 3.5. Lithofacies C: mottled-nodular lime mudstone .............................. 28

Figure 3.6. Lithofacies C: mottled-nodular lime mudstone .............................. 29

Figure 3.7. Lithofacies D: massive-laminated dolomudstone .......................... 31

Figure 3.8. Lithofacies D: massive-laminated dolomudstone .......................... 32

Figure 3.9. Lithofacies E: interlaminated dolomudstone, anhydrite and halite 34

Figure 3.10. Lithofacies E: interlaminated dolomudstone, anhydrite and halite36

Figure 3.11. Lithofacies F: anhydrite ............................................................... 38

Figure 3.12. Lithofacies F: anhydrite ............................................................... 39

Figure 4.1. Stratigraphic section of the Red Head Rapids Formation in Comeault No. 1 well ......................................................................................................... 43

Figure 4.2 (a). Correlation between the Comeault No. 1 and Kaskattama No. 1 wells ................................................................................................................. 47

Figure 4.2 (b). Legend for Figure 4.2............................................................... 48

Figure 5.1 (a). Correlation between the three wells and Cape Donovan outcrop on Southampton Island.................................................................................... 50

Figure 5.1 (b). Legend for Figure 5.1............................................................... 51

Figure 6.1. HI-OI plot of the lithofacies A samples .......................................... 57

Figure 6.2. HI-OI plot of lithofacies samples with samples from Southampton Island ............................................................................................................... 59

Figure 7.1. Tidal flat island model .................................................................... 61

Figure 7.2. Modified tidal flat island model proposed for the Red Head Rapids Formation......................................................................................................... 63

vii

LIST OF TABLES

Table 3.1. Lithofacies Analysis ............................................................................15

Table 4.1. Lithofacies Associations ....................................................................41

Table 6.1. Summary of organic geochemistry results..........................................55

LIST OF APPENDICES

Appendix A: Core descriptions ........................................................................... A1

Appendix B: Thin section descriptions................................................................ B1

Appendix C: X-ray diffraction results (see also enclosed CD-ROM) .................. C1

Appendix D: Rock Eval™ 6 results ..................................................................... D1

1 1 1

CHAPTER 1: INTRODUCTION

1.1 Prologue

The sedimentology of the Paleozoic succession in the Hudson Bay

Basin has not been studied extensively. Limited petroleum exploration has

been conducted in the region because it was previously hypothesized that the

lower Paleozoic succession in the Hudson Bay Basin is thin and has no

petroleum source rock or reservoir potential (Nelson and Johnson, 1966;

Hamblin, 2008). However, more recent studies have compared the Hudson

Bay Basin to the Michigan Basin and Williston Basin, which are petroleum

producing regions, and have postulated that the Hudson Bay Basin has good

petroleum prospects (Hamblin, 2008). As such, the Hudson Bay Basin is

currently viewed as an important frontier prospect. The Geo-mapping for

Energy and Minerals (GEM) program, being led by the Geological Survey of

Canada, focuses mainly on mapping and using modern geological methods to

identify the potential for energy and mineral resources in northern Canada

(Nicolas and Lavoie, 2009).

As part of the GEM program, the Upper Ordovician Red Head Rapids

Formation is being evaluated as a potential petroleum source rock. In the

Houston Oils et al. Comeault STH No. 1 and Sogepet-Aquitaine Kaskattama

Province No. 1 wells in northeastern Manitoba, which are the focus of this

study, the formation consists of carbonate and evaporite rocks. The greyish

green dolomudstone units in these wells have been hypothesized to be

2 1 1

stratigraphically equivalent to oil shales in the northern part of the basin which

are well-exposed in outcrops on Southampton Island, Nunavut.

1.2 Geological Setting

The Hudson Bay Basin is a large intracratonic basin in northern Canada,

covering approximately 600,000 km2, and consists of undeformed sedimentary

rocks of Paleozoic and Mesozoic age (Nelson and Johnson, 1966; Norris,

1993a, 1993b). In the southern part of the Hudson Bay Basin, the Cape

Henrietta Maria Arch separates the Hudson Bay from James Bay in the south

(Fig. 1.1). In the northern part of the Hudson Bay Basin, Southampton Island is

flanked by the Keewatin Arch to the west and the Boothia-Bell Arch to the east.

The Hudson Bay Basin records several tectonic events, including the

Proterozoic Trans-Hudson orogen and the development of an intracratonic

Paleozoic-Mesozoic Hudson Bay Basin (Eaton and Darbyshire, 2010).

Paleozoic sedimentation in the Hudson Bay Basin began with thin

craton-derived siliciclastic and carbonate rocks of Early Ordovician age which

unconformably overlie the Precambrian basement (Sanford and Grant, 1990).

During the Late Ordovician, the uplift of the Cape Henrietta Maria Arch

separated the Hudson Bay Basin and Moose River Basin and a marine

transgression resulted in carbonate and siliciclastic deposition (Sanford and

Grant, 1990). Major glaciation near the end of the Ordovician was recorded as

a major unconformity in the Hudson Bay Basin (Norris, 1993a; 1993b).

3 1 1

Figure 1.1. Geological setting of the Hudson Bay Basin showing the distribution of the Precambrian, Paleozoic and Mesozoic rocks, associated location of various wells in the region (modified from Zhang and Barnes, 2007).

4 1 1

During the Middle Ordovician to Early Cretaceous, the Hudson Bay

Basin was situated close to the paleoequator (Cumming, 1971; Hamblin,

2008). At that time, the region had a dry tropical climate (Cumming, 1971).

1.3 Previous Work

Numerous regional studies of the Hudson Bay Basin have been

conducted and they include Nelson and Johnson (1966), Norford (1970, 1971)

and Norris (1993a, 1993b). Regional stratigraphic studies of the Hudson Bay

Basin have been done by Nelson (1964), Cumming (1971) and Sanford and

Grant (1990).

Paleozoic outcrop studies in the Hudson Bay Basin and Southampton

Island include Heywood and Sanford (1976) and Norris (1993a, 1993b). More

recently, Nelson and Johnson (2002) examined the Ordovician-Silurian strata

in the Churchill area of the Hudson Bay Lowland, and Zhang (2010) studied

Southampton Island. Biostratigraphic studies of Ordovician conodonts were

described by Branson et al. (1951), Le Fèvre et al. (1976), Barnes et al. (1995)

and Zhang and Barnes (2007). Other biostratigraphic studies of the other

marine fossils include Berry and Boucot (1970), Elias (1991) and Jin et al.

(1993).

Petroleum exploration efforts conducted in the late 1980s in the Hudson

Bay Lowland did not result in any commercially viable discoveries (Hamblin,

2008). However, most of the wells that were drilled focused on the thin

5 1 1

Devonian succession. Organic geochemical studies on the Ordovician oil

shales on Southampton Island were initiated by Macauley (1986) and further

advanced by Hamblin (2008), Zhang and Barnes (2007) and Zhang (2008).

In recent years, the potential for hydrocarbon resources in the Hudson

Bay Basin have been re-assessed in greater detail as part of a new Geo-

mapping for Energy and Minerals (GEM) program, initiated by the Geological

Survey of Canada (Nicolas and Lavoie, 2009, 2010; Lavoie et al., 2010; Zhang,

2010).

1.4 This Study

1.4.1 Study Area

Houston Oils et al. Comeault STH No. 1 and Sogepet-Aquitaine

Kaskattama Province No. 1 wells are located at 56.66666N/90.82222W and

57.07181N/90.17484W, respectively, in northern Hudson Bay Lowland,

northeastern Manitoba (Fig. 1.2). The Houston Oils et al. Comeault STH No. 1

(abbreviated as Comeault No. 1) well was studied in detail over the depth

interval of 472.4- 421.2 m (1550-1382 ft) and the Sogepet-Aquitaine

Kaskattama Province No. 1 (abbreviated as Kaskattama No. 1) was studied in

detail from 654.1-704.1 m (2310-2146 ft).

6 1 1

Figure 1.2. Geologic map of the Hudson Bay Lowland in northeastern Manitoba showing the location of wells in the region, including the Comeault No. 1 and Kaskattama No. 1 wells in this study (modified from Nicolas and Lavoie, 2009).

7 1 1

1.4.2 Objectives

The main objectives of this study of the Red Head Rapids Formation in

the Comeault No. 1 and Kaskattama No. 1 wells are to: 1) characterize the

lithofacies and the lithofacies associations based on cores and thin sections,

(2) interpret the depositional environments, (3) correlate the distinctive units in

the study area to the units in the offshore Hudson Bay Basin using available

core and well-log data, (4) evaluate the petroleum source rock potential of Red

Head Rapids Formation in the study area, and (5) compare the greyish-green

dolomudstone units in the Red Head Rapids Formation in the study area to the

oil shales in the Red Head Rapids Formation on Southampton Island.

1.5 Methodology

1.5.1 Core Examination

For this study, the Red Head Rapids Formation in two wells, the

Comeault No. 1 (465.3-423.4 m) and Kaskattama No. 1 (699.5-667.6 m), was

examined and described. Core descriptions included colour, lithology, texture,

physical sedimentary structures, and the nature of bedding contacts. Core

photographs were taken using a Canon PowerShot SD890 IS. Forty samples

from representative lithologies and from intervals showing interesting features

were chosen for preparation of standard-size thin sections (27x46 mm).

Limestone nomenclature was based on classification scheme of Dunham

(1962) as modified by Embry and Klovan (1972).

8 1 1

1.5.2 Thin Section Petrography

Transmitted light petrography was done on all forty thin sections. The

thin sections were stained with Alizarin Red-S to distinguish calcite from

dolomite, and with potassium ferricyanide to identify ferroan calcite and

dolomite (Dickson, 1966). Descriptions included colour, texture, composition of

allochems and matrix, porosity, cements and other diagenetic features. Visual

estimates were made of the percentages of the different components.

Photomicrographs were taken using a Nikon polarizing microscope with an

attached ECLIPSE 50i POL digital camera and edited using NIS ELEMENTS

F3.0 Software.

1.5.3 X-ray Diffraction

Powder X-ray diffraction (XRD) was used for bulk analysis of the

mineralogy of three samples of lithofacies A (greyish-green dolomudstone;

described in Section 3.2) and one sample of lithofacies B (skeletal wackestone;

described in Section 3.3) to complement the thin section petrography. A

Siemens D5000 automated powder diffractometer was utilized, using CuK!

radiation ("=1.5406 Å), and operated at 40 kV and 40 mA. All four samples

were analyzed from 6 to 66° 2#, using a 0.05 2# step width with 1.0 s per step.

The data were collected using Bruker’s DIFFRAC plus software and processed

using MDI Jade 7.5 XRD search match software.

9 1 1

1.5.4 Rock Eval™ 6

Rock Eval™ 6 pyrolysis analysis, conducted in the Organic

Geochemistry Laboratory at Geological Survey of Canada (GSC) in Calgary,

was done on three samples of lithofacies A (greyish-green dolomudstone;

described in Section 3.2) from the Comeault No. 1 and Kaskattama No. 1 wells

to evaluate the petroleum source rock potential (refer to Chapter 5). The

pyrolysis results for one lithofacies A sample from the Comeault No. 1 well at a

depth of 423.4 m was provided by M. Nicolas from the Manitoba Geological

Survey (MGS). Rock Eval™ 6 pyrolysis involves a gradual heating of samples

from 300 to 550 °C to monitor the released hydrocarbons, carbon dioxide and

carbon monoxide using a flame ionization detector (Behar, 2001). The

procedure ends with complete combustion of the residual rock.

1.5.4 Datum

The stratigraphic datum used for constructing the stratigraphic cross-

section of the Red Head Rapids Formation in the study area is the top of the

Churchill River Group.

10 1 1

CHAPTER 2: STRATIGRAPHY

2.1 Regional Stratigraphy

The Hudson Bay Basin sequence consists of Ordovician, Silurian and

Devonian rocks with a total thickness of at least 1575 m in the central offshore

part of the basin (Sanford et al., 1973). The maximum thickness of the

Ordovician strata varies from 180 m in the Manitoba part of the Hudson Bay

Basin (Cumming, 1971) to 160 m on Southampton Island (Heywood and

Sanford, 1976). The Upper Ordovician succession, in ascending order,

consists of the Bad Cache Rapids Group, Churchill River Group and Red Head

Rapids Formation (Nelson, 1964; Cumming, 1971). The units are of Edenian to

Richmondian age (Zhang and Barnes, 2007). The maximum thickness of the

lower Silurian strata varies from 617 m in the offshore central part of the

Hudson Bay Basin to 305 m on Southampton Island (Norris, 1993b). The

Lower Silurian succession, in ascending order, consists of the Severn River

Formation, Ekwan River Formation and Attawapiskat Formation (Norris, 1993b;

Jin et al., 2003). These formations in the Lower Silurian succession are

predominantly composed of carbonate rocks.

2.2 Upper Ordovician Stratigraphy in the Hudson Bay Lowland

Upper Ordovician strata in the Hudson Bay Lowland are composed of

carbonate, evaporite and siliciclastic rocks which are interpreted to have been

deposited in arid, shallow-marine environments (Nelson, 1964; Cumming,

11 1 1

1971; Norris, 1993a). The Churchill River Group is composed of skeletal

limestones in the lower units and grades upward into dolostones and evaporite

rocks with variable thicknesses ranging from 13 to 90 m (Norris, 1993b) (Fig.

2.1). The Churchill River Group consists of the Caution Creek Formation and

the overlying Chasm Creek Formation (Zhang and Barnes, 2007; Nicolas and

Lavoie, 2010).

Overlying the Churchill River Group, the Red Head Rapids Formation in

the Hudson Bay Lowland is composed of dolomudstones, skeletal

dolomudstones and evaporite rocks with variable thicknesses ranging from

25.6 to 92.2 m (Zhang and Barnes, 2007). The Red Head Rapids Formation

can be correlated with the Stonewall Formation of southern Manitoba (Norford,

1970; Cumming, 1971; Zhang and Barnes, 2007).

2.3 Stratigraphy of the Red Head Rapids Formation in the Study

Area

In the study area, the Red Head Rapids Formation is 41.9 m thick

(465.3-423.4 m) and 31.9 m thick (699.5-667.6 m) in the Comeault No. 1 and

Kaskattama No. 1 wells, respectively. The formation consists of fine-crystalline

dolostone and limestone with sparse fossils, greyish-green dolomudstone and

anhydrite units. The bottom of the Red Head Rapids Formation is defined by

lithostratigraphic studies (discussed in Section 2.2.1). The top of the Red Head

12 1 1

Figure 2.1. Stratigraphy of the Hudson Bay Lowland, northeastern Manitoba (modified from Nicolas and Lavoie, 2010).

13 1 1

Rapids Formation is marked by a disconformity with the Lower Silurian Severn

River Formation representing the Ordovician-Silurian boundary (Le Fèvre et al.,

1976; Norris, 1993b; Zhang, 2008).

The Red Head Rapids Formation is in the Rhipidognathus symmetricus

Zone. The Rhipidognathus symmetricus Zone has a narrow stratigraphic

distribution in the Hudson Bay offshore area and is interpreted to be associated

with the terminal Ordovician Gondwanan glaciation (Barnes et al., 1995;

Zhang, 2008).

!

14 1 1

CHAPTER 3: LITHOFACIES ANALYSIS

3.1 Introduction

The Red Head Rapids Formation in the study area consists of a cyclical

sequence of limestones and dolostones interbedded with minor anhydrite.

Based on the available core data (Appendix A) and thin section descriptions

(Appendix B), six lithofacies are recognized in the Red Head Rapids

Formation: A) greyish-green argillaceous dolomudstone, B) skeletal

wackestone, C) mottled-nodular skeletal lime mudstone, D) massive-laminated

dolomudstone, E) interlaminated dolomudstone, anhydrite and halite, and F)

anhydrite. The characteristics of each lithofacies are summarized in Table 3.1.

3.2 Lithofacies A: Greyish-Green Dolomudstone

3.2.1 Description

Lithofacies A consists of light grey to greyish-green dolomudstone and

ranges from 0.076 to 1.59 m thick (Fig. 3.1). The lower and upper contacts are

sharp. Thin to thick laminations occur commonly and vary from wavy to

straight. Massive dolomudstone is also present in this unit. Palaeophycus

burrows are recognized at 447.5 m in the Comeault No. 1 well.

The dolomudstone is composed of very finely crystalline to

aphanocrystalline, planar-subhedral dolomite and minor micrite occurring in

intercrystalline areas (Fig. 3.2). Locally, there are trace amounts of 4-12 !m

size opaque minerals, most of which are rounded to very rounded. Interparticle

15

Table 3.1. Summary of the main characteristics of lithofacies in the Red Head Rapids Formation from Houston Oils et al. Comeault STH #1 and Sogepet-Aquitaine Kaskattama Province No.1 wells in the study area.

Lithofacies Colour Lithology Thickness (m)

Contacts Sedimentary Structures

Allochems Terrigenous Grains

A Greyish-green dolomudstone

Light grey to

dark grey, or greyish green

Dolomudstone, composed of extremely finely crystalline to aphanocrystalline dolomite

0.076-1.59 Lower and upper: sharp

Very thin to thin laminations vary from straight and parallel to wavy. Massive in some intervals. Recognizable Palaeophycus-like burrows

None <1%. Opaque, rounded to very

rounded (12 µm)

B Skeletal wackestone

Light brown to buff

Skeletal wackestone to rudstone

0.02-0.60 Lower and upper: sharp

Massive 10-50%. Fragments of: crinoids (96-2400 µm,1-20%), bryozoans (600-1400 µm, 1-10%), brachiopods (80-520 µm, 10-20%), tabulate coral (7000 µm, <1%), calcareous sponge spicules? (600 µm, <1%). Undifferentiated skeletal fragments (400-2800 µm, tr-7%). Peloids (40-80 µm, tr-3%), microbial structure? (600-1200 µm, tr-2%)

<1%. Quartz,

subangular to rounded (120-200 µm)

*Note: ?=uncertain, tr=trace amounts. Percentages are listed as a percentage of total whole rock volume, unless specified.

16

Table 3.1 (Continued)

Lithofacies Name

Matrix Cements Authigenic components

(excluding cements)

Porosity Depositional Environment

Lithofacies Association


100%. Non-ferroan dolomicrite

None Not distinguishable <1%. Intercrystall-

ine

Low energy, restricted subtidal environment below storm wave base

Open subtidal


10-30%. Non-ferroan micrite

1-3%. Mostly blocky cement (400 µm) in interparticle pores

<5%. Anhydrite needles as cements (400-2000 µm, tr-2 %), halite (60 µm, tr-2%) in intraparticle pores (60 µm, tr-2%), celestine filling fractures (40-200 µm, tr)

<5%. Interparticle and moldic

porosity

Low energy, restricted subtidal environment below storm wave base

Open marine Subtidal

*Note:?=uncertain, tr=trace amounts. Percentages are listed as a percentage of total whole rock volume, unless specified.

17



Contacts Sedimentary Structures Allochems Terrigenous Grains

C Mottled-nodular

skeletal lime mudstone

Light brown to buff

Skeletal lime mudstone to peloidal packstone

0.20-4.04 Lower and

upper: sharp

Mottled-nodular; size of nodules ranging from 0.8-2.5 cm);1 cm intervals of thin laminations, distinct to faint, varying from wavy to straight.

5-50%. Fragments of: crinoids (40-360 µm, 1-35%), brachiopods (80-520 µm, <1%), solitary rugose corals (400-600 µm, 0-2%), gastropods (320-500 µm, tr-3%). Undifferentiated skeletal fragments (80-640 µm, 1-10%). Peloids (40-100 µm, 0-30%).

0-2%. Opaques (16 µm)

D Massive-laminated

dolomudstone

Light brown to light grey

Dolomudstone composed of very fine to fine crystalline non-ferroan dolomite

0.73-0.91 Lower: sharp. Upper: slightly

erosional and

sharp

Thin laminations vary from straight and parallel to wavy near the top contact

Angular-rounded micritic intraclasts (up to 4 mm in size) near the top contact.

<1%. Opaques (20 µm, tr-3%), quartz (40 µm, tr)


18


Lithofacies Name

Matrix Cements Authigenic components (excluding cements)



C Mottled-nodular

skeletal lime mudstone

35%. Non-ferroan micrite, microspar and

dolomicrite

10%. Coarsely-blocky and bladed prismatic, non-ferroan calcite (5-10%) in interparticle pores

3-10%. Planar-euhedral to planar-subhedral, finely crystalline dolomite partly replacing matrix (<64 µm, <7%). Anhydrite needles (480-3000 µm, 1-2%) in matrix and interparticle pores, halite (40 µm, tr) in interparticle porosity

<5%. Interparticle

(tr) and moldic (60-

80 µm, <5%)

Shallow subtidal environment, open circulation with low-moderate energy conditions

Open subtidal

D Massive-laminated

dolomudstone

85-100%. Non-ferroan

dolomitic aphano-

crystalline-micrite

3-15%. Anhydrite cement in interparticle pores.

None <1%. Interparticle (tr), vuggy

(tr)

Shallow subtidal environment, restricted circulation and saline conditions

Saline-subtidal


19



Contacts Sedimentary Structures Allochems Terrigenous Grains

E Interlaminated dolomudstone, anhydrite and

halite

Brown to buff

Dolomudstone, composed of very finely crystalline to aphanocrystalline dolomite; anhydrite, coarsely crystalline; and halite, medium crystalline

0.11-2.70 Lower and

upper: sharp

Thin to thick laminations, varying from straight and parallel to wavy. 3 to 8 cm-thick anhydrite beds (with needle like texture) and 0.2 cm to 1.3 m-thick dolomudstone

0-20%. Peloids (16-80 µm, 5-7%). Sub-angular to rounded micritic intraclasts

0-3%. Opaques (840-1800 µm)

F Anhydrite Bluish grey to white and

translu-cent

Anhydrite, medium crystalline to extremely coarsely crystalline; finely crystalline displacive halite, medium crystalline gypsum and very finely crystalline dolomite in matrix

0.16-3.80 Lower and

upper: sharp

Anhydrite typically in the following succession (bottom to top): 1. massive anhydrite (up to 0.3 m thick) 2. laminated anhydrite (up to 1 m thick) with disseminated dolomite 3. nodular anhydrite (up to 1.8 m thick) 4. mosaic anhydrite (up to 1.2 m thick) 5. rare enterolithic (up to 0.08 m thick) 6. chicken-wire anhydrite and rarely gypsum (up to 0.05 m thick)

None <1%. Opaques (16

µm)

*Note: ?=uncertain, tr=trace amounts. Percentages are listed as a percentage of total whole rock volume, unless specified.

20


Lithofacies Name

Matrix Cements Authigenic components (excluding cements)



E Interlaminated dolomudstone, anhydrite and

halite

2-25%. Non-ferroan

dolomicrite

10-40%. Drusy to blocky, non-ferroan calcite cement (4 µm, tr-10%) interparticle. Planar-subhedral and planar-euhedral, finely crystalline dolomites in interparticle porosity (8-12 µm, 10-50%). Anhydrite cement in interparticle porosity (4-10 µm, tr-5%)

<5-10%. Planar-euhedral to subhedral, finely crystalline dolomite, replacing dolomites matrix in interparticle porosity (<64 µm). Anhydrite needles in interparticle porosity (200-1600 µm, tr), euhedral halite crystals in interparticle porosity (16 µm, tr)

<1%. Intraparticle and vuggy

porosity

Low energy, saline to restricted environment, shallow subtidal.

Saline- subtidal

F Anhydrite 0-10%. Non-ferroan dolomicrite (16-40 µm, <5%); non-ferroan micrite

(aphano-crystalline, <5%)

occurring in intercrystalline

pores

None <1%. Displacive halite (16 µm, tr), gypsum in interparticle porosity (0.4-1 cm, tr), anhydrite (white and translucent) filling millimeter-wide fractures near top contact

- Low energy, hypersaline conditions.

Saline mud flat


21 1 1

Figure. 3.1. Core photographs of lithofacies A: greyish-green dolomudstone. (A) Bioturbated dolomudstone with burrows (pink arrows) and a sharp upper contact with lithofacies B (skeletal dolowackestone), Comeault No. 1, 447.5 m, 1468.3 ft. (B) Dolomudstone with Palaeophycus burrows (green arrows), Comeault No. 1, 448 m, 1470 ft.

22 1 1

Figure 3.2. Lithofacies A: greyish-green argillaceous dolomudstone. (A) Core photograph of massive dolomudstone. Red box indicates area of thin section shown in (B), Kaskattama No. 1, 695.06 m, 2280 ft. (B) Photomicrograph of massive dolomudstone from (A) showing very finely crystalline to aphanocrystalline, planar-subhedral dolomite (white) and micrite (brown). Plane polarized light, Kaskattama No. 1, 695.06 m, 2280 ft.

23 1 1

and intraparticle porosity is <1%.

X-ray diffraction (XRD) analysis on two selected samples from the

Comeault No. 1 well (432.21 m and 432.51 m) and one sample from the

Kaskattama well (669.04 m) indicates that the samples are composed of

primarily dolomite and anhydrite (refer to Appendix C). The clay mineral

content was insufficient for any further XRD analysis.

2.2.2 Interpretation

The greyish-green dolomudstone lithofacies is interpreted to have been

deposited in a low energy subtidal environment. The greyish green colour of

the argillaceous mudstone suggests decomposition of organic matter under

oxidizing conditions. The presence of laminations indicates that the sediments

probably accumulated below storm wave base. The abundance and

preservation of straight and parallel laminations, undisturbed by bioturbation,

suggest restricted conditions.

3.3 Lithofacies B: Skeletal Wackestone

3.3.1 Description

Lithofacies B consists of light brown to buff, skeletal wackestone to

rudstone and ranges from 0.02 to 0.60 m thick (Fig. 3.3). The lower and upper

contacts are sharp. This lithofacies is generally massive.

24 1 1

Figure 3.3. Core photographs of lithofacies B: skeletal wackestone. (A) Skeletal wackestone-floatstone with large crinoid fragments (red arrows) and some unidentifiable skeletal fragments, Comeault No. 1, 457.02 m, 1499.4 ft. (B) Skeletal wackestone with fractures filled by celestine (black arrow) and displacive anhydrite needles (blue arrows), Comeault No. 1, 446.93 m, 1466.3 ft.

25 1 1

The major allochems in lithofacies B are fragments of crinoids,

bryozoans, brachiopods and tabulate corals (Paleofavosites), and

undifferentiated skeletal fragments (Fig. 3.4). Peloids and silt- and sand-size

quartz are minor constituents. The matrix consists of non-ferroan micrite.

Blocky calcite cement (~400 !m crystal size) occurs commonly in interparticle

pore spaces. Anhydrite needles (up to 1.2 cm length) in the matrix, and very

fine crystalline halite crystals in intraparticle pores, respectively, are scattered

throughout the lithofacies. Medium crystalline celestine fills in millimetre-wide

fractures and fine crystalline anhydrite lines fracture walls. The mineral

identification was done on a sample from Comeault No. 1, 446.93 m, 1466.3 ft.

using XRD analysis. Interparticle and moldic porosity is <1% of total porosity.


Lithofacies B is interpreted to have been deposited in a low to moderate

energy, open subtidal environment. The abundance of crinoids and

brachiopods suggests open circulation in waters of normal marine salinity (cf.

Flügel, 2010). The micrite matrix indicates generally quiet conditions. Silt- and

sand-size quartz is interpreted as eolian in origin, possibly having been

transported from a distant landmass. Anhydrite and celestine, which fill

fractures, are diagenetic.

26 1 1

Fig. 3.4. Photomicrographs of lithofacies B: skeletal wackestone (cross polarized light). (A) Skeletal wackestone with brachiopods (Br), crinoids (C) and micrite matrix (m), Comeault No. 1, 457.02 m, 1499.4 ft. (B) Skeletal wackestone showing a tabulate coral (Paleofavosites) (Co) that is mostly infilled with micrite (m) and blocky calcite cement (Cc), and a crinoid fragment (C) and brachiopod fragment (Br), Comeault No. 1, 457.97 m, 1509.1 ft. (C) Skeletal wackestone with fractures filled by celestine (Cs) and anhydrite (An), Comeault No. 1, 446.93 m, 1466.3 ft.

1 mm

27 1 1

3.4 Lithofacies C: Mottled-Nodular Skeletal Lime Mudstone

3.4.1 Description

Lithofacies C consists predominantly of light brown to buff, mottled to

nodular, skeletal lime mudstone and peloidal packstone, ranging from 0.20 to

4.04 m thick (Fig. 3.5). The lower and upper contacts are sharp. Thin

laminations occur in centimetre-thick intervals and vary from wavy to straight.

Light brown to buff nodules range in size from millimetres to centimetres and

typically decrease in size and are more irregular in shape up-section. The

internodular matrix is darker in colour and consists of micrite.

The major allochems in lithofacies C are fragments of crinoids,

brachiopods, solitary rugose corals and gastropods, and undifferentiated

skeletal fragments (Fig. 3.6). The matrix consists of non-ferroan micrite and

dolomicrite, composed of finely crystalline, planar-euhedral dolomite. Coarse-

blocky and bladed prismatic, non-ferroan calcite cement occurs commonly in

interparticle pore spaces. This lithofacies has <5% interparticle and moldic

porosity.


Lithofacies C is interpreted to have been deposited in a low to moderate

energy, open subtidal environment. As previously discussed for lithofacies B,

the abundant fragments of crinoids and brachiopods suggest open circulation

in waters of normal marine salinity (cf. Flügel, 2010). The mottled texture

28 1 1

Figure 3.5. Core photographs of lithofacies C: mottled-nodular skeletal lime mudstone. (A) Mottled-nodular lime mudstone with lighter nodules (black arrows) that decrease in size and are more irregular in shape near the top, Comeault No. 1, 440.44 m, 1455 ft. (B) Skeletal lime mudstone with mottled-nodular texture (red arrow) and brachiopods (black arrow) and anhydrite laths (indicated by blue arrows), Comeault No. 1, 441.35 m, 1448 ft.

29 1 1

Figure 3.6. Photomicrographs of lithofacies C: mottled-nodular skeletal lime mudstone (cross polarized light). (A) Skeletal wackestone composed of crinoid (C), equant calcite micrite and microspar in nodules (n), micrite as internodular matrix and undifferentiated skeletal fragment (Sk) in micrite with a nodular texture, Comeault No. 1, 471. 53 m, 1547 ft. (B) Peloidal packstone showing peloids (P) and a gastropod fragment (G) infilled with blocky and bladed prismatic calcite cement, Comeault No. 1, 441.35 m, 1448 ft.

30 1 1

suggests bioturbation occurred where sedimentation rates were sufficiently

low to have allowed the organisms to have reworked the substrate (cf. Flügel,

2010). The nodular texture is diagenetic and probably caused by selective

calcite cementation within the sediment (cf. Flügel, 2010). The abundance of

peloids indicates deposition in a tropical shallow marine environment.

3.5 Lithofacies D: Massive-Laminated Dolomudstone

3.5.1 Description

Lithofacies D consists of light brown to light grey dolomudstone and

ranges from 0.73 to 0.91 m thick (Fig. 3.7). The lower contacts are sharp and

the upper contacts are slightly erosional and sharp. This lithofacies has

centimetre- to millimeter-thick laminations which vary from straight and parallel

to wavy.

The massive-laminated dolomudstone is composed mostly of

aphanocrystalline non-ferroan dolomicrite (Fig. 3.8). Sub-angular to rounded

dolomicrite intraclasts (up to 4 mm in size) with a micrite rim occur locally.

Equant, finely crystalline calcite and euhedral, medium crystalline halite

occurring as cement in intraparticle pore spaces. Interparticle and vuggy

porosity is <1%.

31 1 1

Figure 3.7. Core photographs of lithofacies D: massive-laminated dolomudstone. (A) Dolomudstone with thin to thick planar laminations (black arrow), Comeault No. 1, 458.2 m, 2295 ft. (B) Dolomudstone with fine laminae (black arrow), Kaskattama No. 1, 669.5 m, 2195 ft.

32 1 1

Figure 3.8. Photomicrographs of lithofacies D: massive-laminated dolomudstone (crossed polarized light). (A) Dolomudstone with anhydrite (An) and halite (Ha), dolomicrite (dm) and dolomicrite intraclast (int), Kaskattama No. 1, 673 m, 2208 ft. (B) Laminated dolomudstone with micrite (m), dolomicrite (d) and finely crystalline halite crystals (Ha) in dolomicrite, Kaskattama No. 1, 669.5 m, 2195 ft.

33 1 1


Lithofacies D is interpreted to have been deposited in a low energy,

restricted, saline subtidal environment. The abundance of dolomicrite and

presence of planar laminations are interpreted to represent deposition under

quiet energy conditions (cf. Folk, 1959; Flügel, 2010). The lack of bioturbation

and skeletal components suggests a depositional setting that has more

restricted circulation than lithofacies B and C (cf. Flügel, 2010). The

laminations suggests deeper water setting below wave base (Flügel, 2010).

The presence of late-diagenetic halite crystals suggests elevated salinities.

3.6 Lithofacies E: Interlaminated Dolomudstone, Anhydrite and Halite

3.6.1 Description

Lithofacies E consists of light and medium brown to buff, interlaminated

and interbedded dolomudstone, anhydrite and halite (Fig. 3.9), ranging from

0.11 to 2.70 m thick (Fig. 3.9). The lower and upper contacts are sharp. Thin

to thick laminations vary from straight and parallel to wavy. Individual

dolomudstone laminations are millimeter thick and typically occur

interlaminated with centimeter-thick massive anhydrite beds. Halite beds, 2-5

cm thick, are rare.

The dominant allochems in lithofacies E are peloids. Sub-angular to

rounded micritic intraclasts (up to 1.8 mm in size) occur locally and most are

elongate and sub-parallel to bedding. Most of the porosity is cemented by the

34 1 1

Figure 3.9. Core photographs of lithofacies E: interlaminated dolomudstone, anhydrite and halite. (A) Dolomudstone interlaminated with anhydrite laminae composed of fine anhydrite needles (An-n), Kaskattama, 477.45 m, 2222.6 ft. (B) Dolomudstone beds (d-b; black arrows indicating interval) interlaminated with anhydrite laminae (An), Comeault, 471.53 m, 1547 ft. (C) Anhydrite and halite interlaminated (An-l) with finely laminated dolomudstone, Kaskattama, 696.97 m, 2286.65 ft.

35 1 1

coarse crystalline, planar- euhedral-subhedral dolomite and drusy to blocky

calcite. Intraparticle and vuggy porosity is <1%.


Lithofacies E is interpreted to have been deposited in a low energy,

saline subtidal environment. The straight and parallel millimeter scale

dolomicrite laminations intercalated with thin anhydrite and halite laminations

and thick dolomudstone beds are indicative of low energy conditions.

Interlaminated anhydrite and dolomudstone is common in elevated

salinity environments of relatively shallow water depths (Kendall, 1992; Flügel,

2010). The relative abundance of displacive anhydrite needles and subhedral

halite crystals in this lithofacies suggests that salinities were sufficiently

concentrated to preserve precipitate halite in a dolomudstone from an

evaporative drawdown (cf. Kendall, 1992). No obvious evidence of subaerial

exposure was observed in this lithofacies.

36 1 1

Figure 3.10. Photomicrographs of lithofacies E: interlaminated dolomudstone, anhydrite and halite (plane polarized light). (A) Dolomudstone (d) with interlaminated anhydrite (An) and large, acicular anhydrite needles at the base of the lamina, Comeault No. 1, 458.5 m, 1504.4 ft. (B) Dolomudstone (d) with halite crystals (Ha) Kaskattama No. 1, 667.5 m, 2190 ft.

37 1 1

3.7 Lithofacies F: Anhydrite

3.7.1 Description

Lithofacies F consists of bluish-grey to white, translucent anhydrite and

ranges from 0.16 to 3.80 m thick (Fig. 3.11; 3.12). The lower and upper

contacts are sharp. Thin to thick laminations occur in centimetre-thick intervals

and vary from wavy to straight.

This lithofacies is composed of various lithologies: massive anhydrite

(up to 0.3 m thick), laminated anhydrite (up to 1 m thick), nodular anhydrite

with a mean size of 3.5 cm (up to 0.18 m thick), mosaic anhydrite with a size

range of 0.5 to 1.0 cm (up to 1.2 m thick), enterolithic anhydrite (up to 0.08 m

thick), and chicken-wire anhydrite (up to 0.05 m thick). Massive anhydrite is

typically found near the base, and is overlain by laminated anhydrite with

dolostone laminae, followed by nodular anhydrite. Anhydrite nodules increase

in size upward in the unit. Enterolithic anhydrite and chicken-wire anhydrite are

rarely observed near the top.

Non-ferroan dolomicrite and/or non-ferroan micrite occur in

intercrystalline spaces in the laminated anhydrite. Coarsely crystalline

anhydrite and extremely coarsely crystalline gypsum fill near-vertical,

millimeter-wide fractures.

38 1 1

Figure 3.11. Core photographs of lithofacies F: anhydrite. (A) Chicken-wire anhydrite, Comeault No. 1, 461.25 m, 1436.8 ft. (B) Interlaminated dolostone and anhydrite, Comeault No. 1, 463.3 m, 1520 ft. (C) Enterolithic anhydrite with arrows pointing to the folded anhydrite layers, Comeault No. 1, 637.9 m, 1513 ft.

39 1 1

Figure 3.12. Lithofacies F: anhydrite. (A) Mosaic anhydrite (black arrows indicating the mosaic interval) underlain and overlain by laminated anhydrite, Comeault No. 1, 433.2 m, 1421.1 ft. (B) Massive anhydrite, Comeault No. 1, 434.5 m, 1426.7 ft. (C) Photomicrograph of anhydrite needles (An) and dolomicrite (dm) (crossed polarized light), Comeault No. 1, 677.5 m, 2222.6 ft.

40 1 1


Lithofacies F is interpreted to have been deposited under low energy,

hypersaline conditions as evidenced by the predominance of anhydrite but

suggests elevated salinity compared to lithofacies E (interlaminated

dolomudstone, anhydrite and halite). The presence of massive anhydrite near

the base, suggests formation from gypsum mush layers (cf. Kendall, 1992).

This lithofacies is suggested to be of a saline mud flat depositional

setting. The presence of nodular anhydrite and mosaic anhydrite, formed by

replacing earlier gypsum (cf. Hardie and Shinn, 1986; Kendall, 2010) in some

intervals, suggests an increasingly restricted circulation (cf. Warren, 2006).

Upward in the succession, chicken-wire anhydrite reflects a supratidal zone

(cf. Warren, 2006) and enterolithic anhydrite is formed by irregular and folded

anhydrite layers with continual growth in quiet environments in a supratidal

zone (cf. Kendall, 1992; Warren, 2006). However, the anhydrite nodules

typically are formed by replacing gypsum crystals during early diagenesis, but

may also be influenced by later diagenesis such as burial and compaction (cf.

Kendall, 1992; Warren, 2006) (Fig. 3.12). The absence of desiccation cracks

and tepee structures suggests that the saline mudflat was probably subaerially

exposed for relatively short periods of time (cf. Kendall, 1992).

41 1 1

CHAPTER 4: LITHOFACIES ASSOCIATIONS AND METER-

SCALE CYCLICITY

4.1 Lithofacies Associations

!

The six lithofacies identified in the Red Head Rapids Formation in the

study area, as described in Chapter 3, can be grouped genetically into three

lithofacies associations: 1) open subtidal; 2) saline subtidal and 3) saline mud

flats (Table 4.1).

Table 4.1. Lithofacies associations recognized in the Red Head Rapids Formation in the study area.

The open-subtidal lithofacies association consists predominantly of

lithofacies A, greyish-green dolomudstone; lithofacies B, skeletal wackestone;

and lithofacies C, mottled-nodular skeletal lime mudstone. The latter two

lithofacies are interpreted to have been deposited in normal subtidal

Lithofacies Name Lithofacies Association

F Anhydrite Saline mud flat

E Interlaminated dolomudstone, anhydrite and halite

D Massive-laminated dolomudstone

Saline subtidal

C Mottled-nodular skeletal lime mudstone



Open subtidal

42 1 1

conditions, between fair-weather and storm wave base, as discussed in

Sections 3.3 and 3.4. However, lithofacies A is interpreted to represent more

restricted conditions (discussed in Section 3.2).

The saline subtidal lithofacies association consists of lithofacies D,

massive-laminated dolomudstone, and lithofacies E, interlaminated

dolomudstone, anhydrite and halite. Both lithofacies are interpreted to have

been deposited in low energy, saline subtidal environments, as discussed in

Sections 3.5 and 3.6. The evenly laminated nature of lithofacies E suggests

that this lithofacies represents a slightly deeper water setting below wave base

than lithofacies F.

The saline mudflat lithofacies association consists of lithofacies F,

anhydrite. As discussed in Section 3.7, lithofacies F is interpreted to have

been deposited in a low energy, supratidal to intertidal environment.

4.2 Meter-Scale Cyclicity

The three lithofacies associations in the Red Head Rapids Formation in

the study area comprise four meter-scale cycles, 9.4 to 19 m thick (Fig. 4.1).

Individual cycles consist of an open subtidal lithofacies association, is overlain

by the saline subtidal lithofacies association, which is, in turn, overlain by the

saline mud flat lithofacies association. The lower part of cycle 1, which occurs

in the Churchill River Group, was not fully described for this study.

43 1 1

Figure 4.1. Stratigraphic section of the Red Head Rapids Formation in the Comeault No. 1 well, showing the lithofacies and lithofacies associations. The lower part of cycle 1 was not described.

Stylolites

Corals

Gastropods

Crinoids

Brachiopods

Skeletal fragments (undifferentiated)

Symbols

Churchill River Group

Severn River Formation

44 1 1

In the Comeault No. 1 core, cycle 3 (432.9-449.1 m; 1420.3-1473.4 ft.)

is the thickest cycle and is considered to be the most complete. The lower

open subtidal lithofacies association consists of lithofacies A (greyish-green

dolomudstone) which is overlain by lithofacies B (skeletal wackestone) and

then by lithofacies C (mottled-nodular skeletal lime mudstone). Cycles 2 and 4

are missing lithofacies C and F, respectively.

In the Kaskattama No. 1 core, cycle 2 (696.6 to 682.6 m; 2285.4-2239.5

ft.) is considered to be the most complete. The lower open subtidal lithofacies

association consists of lithofacies A (greyish-green dolomudstone) which is

overlain by a thin bed of lithofacies D and is, in turn, overlain by lithofacies B

and C. Cycle 2 is capped by alternating intervals of lithofacies E and F.

Lithofacies B is absent in cycle 3 and lithofacies B, C, D, E and F are absent in

cycle 4.

The four cycles are interpreted to be shallowing and brining-upward

cycles (cf. Warren, 2006). In the Kaskattama No.1 well, the repeated interbeds

of lithofacies E and F in cycles 2 and 3 shows evidence of a fluctuating water

depth during deposition from the saline mud flat lithofacies association to the

saline subtidal lithofacies association.

45 1 1

4.3 Correlation of Meter-Scale Cycles

The four cycles, described previously, can be readily correlated

between the Comeault No. 1 and the Kaskattama No. 1 wells (Fig. 4.2). This

correlation reveals some significant lithofacies variations between the two

wells.

Cycle 1 in both wells has thick successions (9 to 14.6 m) of the open

subtidal and saline subtidal lithofacies. The Comeault No. 1 well is capped by

a thick saline mudflat succession lithofacies association with nodular

anhydrite, whereas in the Kaskattama No. 1 well, the saline mud flat lithofacies

association is represented by a thin interval of laminated anhydritic

dolomudstone.

Cycle 2 in the Comeault No. 1 well has a thinner succession of the

open subtidal lithofacies association, and a thicker saline subtidal lithofacies

association than the Kaskattama No. 1 well.

In the Kaskattama well, cycle 3 is 12.2 m thick, and is capped by a

thicker saline mud flat lithofacies association, compared to the cycle 3 in the

Comeault No. 1 well.

Cycle 4 was described only in the basal portion of the Comeault No. 1

well. In the Kaskattama well, cycle 4 is truncated by dolofloatstone and is

considered to represent the disconformity between the Red Head Rapids

46 1 1

Formation and the overlying Lower Silurian Severn River Formation (Le Fèvre

et al., 1976; Jin et al., 1993).

47 1 1

Fig

ure

4.2

(a).

Cyc

lical

cor

rela

tion

betw

een

the

Kas

katta

ma

No.

1 a

nd C

omea

ult N

o. 1

wel

ls in

the

stud

y ar

ea.

48 1 1

Figure 4.2 (b). Legend for Figure 4.2 (a).

49 1 1

CHAPTER 5: STRATIGRAPHIC CORRELATION

5.1 Introduction

To better understand the lateral facies variation of the Red Head

Rapids Formation in the Hudson Bay Lowland, correlation was attempted

between the Comeault No. 1 and Kaskattama No. 1 wells, the offshore Polar

Bear C-11 well and the Cape Donovan outcrop on Southampton Island

(Fig.1.1).

5.2 Correlation Between Comeault No. 1, Kaskattama No. 1 And

Polar Bear C-11 Wells

In the offshore Polar Bear C-11 well (5959121N/ 8678847W), the Red

Head Rapids Formation is 87.5 m thick, occurring at a depth of 1399.1 to

1311.6 m (4306-4591 ft.) (Aquitaine Company of Canada, 1974). Based on

the drill cuttings, the formation has been described as consisting of white to

brown limestone and tan to brown dolomitic limestone with minor amounts of

anhydrite and halite. Although detailed lithologic relationships cannot be

worked out, three carbonate-evaporite cycles can be identified in the Polar

Bear C-11 well (Fig. 5.1).

Cycle 1 in the Polar Bear C-11 well is 29 m thick has a basal shale unit,

which is overlain by dolostone and capped by a thick sequence of gypsum and

anhydrite. Cycle 2, 22.3 m thick, is composed of interbedded evaporite rocks

and dolostone with an interval of dolostone with gypsum and anhydrite in the

50 1 1

Fig

ure.

5.1

(a)

. Cor

rela

tion

of th

e th

ree

wel

ls w

ith th

e ou

tcro

p at

Cap

e D

onov

an, S

outh

ampt

on

Isla

nd (

ref)

. The

Cap

e D

onov

an o

utcr

op h

as a

diff

eren

t sca

le.

51 1 1

Figure 5.1 (b). Legend for Figure 5.1 (a).

52 1 1

lower portion of the cycle. Cycle 3 is 36.2 m thick and is dominated by

intervals of anhydrite and gypsum.

In comparison to the 3 cycles identified in the Comeault No. 1 well and

Kaskattama No. 1 well, the cycles in the Polar Bear C-11 are generally thicker.

Cycle 2 in the Comeault No. 1 well, Kaskattama No. 1 well and the Polar Bear

C-11 well has variable thicknesses. In the Comeault No. 1 well, the evaporite

interval is thin, whereas in the Kaskattama No. 1 well and Polar Bear C-11

well, the evaporite is interbedded with dolomudstone. In the Polar Bear C-11

well, cycle 3 has the thickest evaporite bed, consisting of salt, gypsum and

anhydrite. Similar to the Kaskattama No. 1 well, cycle 4 is absent in the Polar

Bear C-11 well in the Red Head Rapids Formation.

In addition, using biostratigraphic studies, the Rhipidognathus

symmetricus Zone (Branson et al., 1951), as discussed in Chapter 2, has been

recognized in the Red Head Rapids Formation in both the Comeault No. 1 and

Polar Bear C-11 wells (Le Fèvre et al., 1976; Zhang and Barnes, 2007) and is

used for correlation (Fig. 5.1).

5.3 Correlation With The Cape Donovan Outcrop, Southampton

Island

Recent studies of the Red Head Rapids Formation exposed in outcrops

at Cape Donovan on Southampton Island have focused on the Ordovician-

Silurian boundary and the petroleum potential of the oil shales in the formation

(Zhang, 2008).

53 1 1

The exposed Red Head Rapids Formation on Southampton Island is

46.2 m thick with each shale interval 0.3 to 1.0 m thick (Zhang, 2008) (Fig.

5.1). Cycle 1 consists of oil shale in the lower portion of the succession and

brecciated dolomudstone and laminated dolostone in the upper portion of the

succession. Cycle 2 has a thin bed of oil shale in the basal portion which is

overlain by argillaceous dolomudstone, massive dolomudstone, laminated

dolomudstone. Cycle 3 consists of thin beds of oil shales overlain by

brecciated dolomudstone and massive limestone at the top of the cycle.

Three intervals with positive kicks from the gamma ray log from the

Polar Bear C-11 well have been correlated with the three oil shale intervals in

Cape Donovan (Zhang, 2008) (Fig. 5.1).

54 1 1

CHAPTER 6: ORGANIC GEOCHEMISTRY

6.1 Introduction

Three samples of lithofacies A (greenish-grey dolomudstone), in the

Red Head Rapids Formation in the study area, previously described in Section

3.2, were analyzed using Rock Eval™ 6 pyrolysis to evaluate the source rock

potential of the lithofacies. The results were compared to oil shale intervals in

the Red Head Rapids Formation on Cape Donovan, Southampton Island,

which have been studied in detail by Zhang (2008).

By convention, an excellent source rock has a total organic carbon

(TOC) value of >10 wt.%, a good source rock has a TOC value of 2-10 wt.%

and an uneconomical source rock has a TOC value <2 wt.% (Allen and Allen,

1990). The production index (PI) is a measure of hydrocarbon generation,

where S1 and S2 are the areas below the two peaks recorded from Rock

Eval™ 6 pyrolysis (Lafargue et al., 1998). S1 represents the volume of the free

hydrocarbons in the sample, and S2 represents the hydrocarbons that could

still be generated during thermal cracking of the kerogen in the sample. A PI

ratio of 0.1 is the minimum for oil generation. The Tmax value correlated to the

maximum temperature a sample has been subjected to during burial and thus

indicates the maturity of the sample (Hunt, 1996). The temperature range,

435-465 ºC, is considered a potential source rock in conventional oil and gas

systems (Hunt, 1996) when using Rock Eval™ 6 instrumentation (Lafargue et

al., 1998). Rock Eval™ 6/ TOC data are best interpreted using large

55 1 1

databases. Given the small number of samples analyzed, interpretation is

limited for this study.

6.2 Results For Total Organic Carbon (TOC), Maximum Temperature

(Tmax) and Production Index (PI)

The results of the Rock Eval™ 6/TOC analysis for the three samples of

lithofacies A (greyish-green argillaceous dolomudstone) are summarized in

Table 6.1. Detailed data are provided in Appendix D.

Table 6.1. Summary of Rock Eval™ 6/TOC results from the Red Head Rapids Formation in the study area.

Well Depth (m)

Depth (ft)

Total Organic Carbon, TOC (wt. %)

Production Index, PI

Maximum Temperature, Tmax (ºC)

Comeault No. 1 432.2 1418 0.37 0.19 431

Comeault No. 1 423.4 1389 0.42 0.27 415

Kaskattama No. 1 669.3 2195 0.34 0.11 440

The TOC values for the three samples range from 0.34 to 0.42 wt.%,

and are too low to indicate a good source rock. Only one sample (Kaskattama

No. 1 well, 669.3 m, 2195 ft.) plots in the oil window with a Tmax of 440 ºC. The

other two samples have Tmax values that are slightly below the oil window and

are considered to be thermally immature. The PI ratios range from 0.11 to 0.27

and are at the lower end of the PI range expected for a thermogenic system

(0.1 to 1.0) (cf. Lafargue et al., 1998). This suggests that very light

56 1 1

hydrocarbons were released during the early heating of the samples (cf.

Lafargue et al., 1998).

6.3 Hydrogen Index-Oxygen Index (HI-OI) Plot

The Hydrogen Index (HI) is the ratio of S2/TOC, and the Oxygen Index

(OI) is the ratio of S3/TOC, where S3 represents the volume of CO and CO2

produced (Peters, 1986; Lafargue et al., 1998). Plots of Hydrogen-Oxygen

indices (HI-OI) are used to determine the kerogen types (Fig. 6.1) (Peters,

1986). Type I and II kerogens are of marine origin and oil-prone. Type III

kerogen is of terrestrial origin and gas prone.

Although the data set is very small, the results are plotted on a modified

van Krevelen diagram for a preliminary evaluation (Fig. 6.1). Two samples

from the Comeault No. 1 well (423.4 m, 1389 ft.; 432.2 m, 1418 ft.) plot close

to the Type III kerogen curve suggesting a possible terrestrial origin for the

organic matter that has been transported into the subtidal depositional setting.

Oxidation of marine organic matter in shallow water could be an alternative

explanation for the Comeault No. 1 sample (432.2 m, 1418 ft.) plotting close to

the Type III kerogen line (cf. Hunt, 1996).The Kaskattama No. 1 sample (669.3

m; 2195 ft.) falls between the Type II and Type III kerogen lines (Fig. 6.1). The

higher proportion of Type II kerogen in this sample suggests that the organic

matter may be a combination of both marine and terrestrial origin.

57 1 1

Figure 6.1. Modified van Krevelen HI-OI plot of lithofacies A samples from the Red Head Rapids Formation in the study area. Comeault No. 1 samples: C-1418, 432.2 m, 1418 ft. and 106-1-HBL, 423.4 m, 1389 ft. Kaskattama No. 1 sample: K-2195, 669.3 m, 2195 ft. Lines labelled Types I, II, III kerogen are from Peters (1968).

58 1 1

6.4 Comparison to the Red Head Rapids Formation, Cape Donovan, Southampton Island

!

Rock Eval™ 6 pyrolysis analysis was conducted by Zhang (2008) on

three oil shale intervals in outcrops of the Red Head Rapids Formation at

Cape Donovan, Southampton Island. A total of 52 samples were analyzed.

The TOC values range from 0.19 wt.% to 30.96 wt.%, PI values range from

0.01 to 0.04 and Tmax values range from 409 to 426 ºC. TOC values for the

Cape Donovan samples are significantly higher than the TOC values from the

Comeault No. 1 and Kaskattama No. 1 samples, but the PI values for the

Cape Donovan samples are lower. The Tmax values for the samples from

Cape Donovan and the two wells are similar. The three oil shale intervals from

Cape Donovan and lithofacies A (greyish-green dolomudstone) in this study

have been being interpreted as thermally immature (Zhang, 2008; M. Nicolas,

2010, pers. comm.).

On a modified van Krevelan diagram, most of the samples from Cape

Donovan plot between Type I and II kerogen lines (Fig. 6.2), indicating that the

organic matter is of marine origin and oil-prone. In contrast, the Comeault No.

1 and Kaskattama No. 1 samples which plot closer the Type II and III kerogen

lines contain organic matter that may be both terrestrial and marine in origin.

59 1 1

Figure 6.2. Modified van Krevelen HI-OI plot for samples from lithofacies A the Red Head Rapids Formation in the study area and oil shales at Cape Donovan, Southampton Island (Zhang, 2008). Comeault No. 1 samples: C-1418, 432.2 m, 1418 ft. and 106-1-HBL, 423.4 m, 1389 ft. Kaskattama No. 1 sample: K-2195, 669.3 m, 2195 ft. Lines labelled Types I, II, III kerogen are from Peters (1968).

60 1 1

CHAPTER 7: DISCUSSION

7.1 Introduction

In this chapter, the stratigraphy, sedimentology, and organic

geochemistry of the Red Head Rapids Formation are integrated in order to: (1)

interpret the development of cyclicity, (2) understand the paleogeography of

the basin and (3) evaluate the controls on source rock potential.

7.2 Tidal Flat Island Model

The tidal flat island model is considered to be the most suitable

depositional model for interpreting the Red Head Rapids Formation in the study

area (Fig. 7.1). The model was first proposed by Pratt and James (1986) to

explain the peritidal cycles in Lower Ordovician carbonate strata in western

Newfoundland. The subtidal, intertidal and supratidal lithofacies associations in

these cycles are laterally discontinuous. The peritidal cycles are postulated to

represent small tidal flat islands prograding landward and aggrading to sea

levels in large and shallow epeiric seas (Pratt and James, 1986; Pratt et al.,

1992).

61 1 1

Figure 7.1 Tidal flat island model illustrating the tidal islands nucleating and accreting by aggradation and progradation and shifting in response to hydrographic forces (modified from Pratt et al., 1992).

62 1 1

The tidal flat island model provides an explanation for the shallowing-

upward cycles and the laterally discontinuous nature of the lithofacies identified

in the Red Head Rapids Formation (Fig. 7.2). In addition, the brining-upward

nature of cycles, as discussed in Section 4.1 and 4.2, lithofacies F (anhydrite)

caps each shallowing and brining-upward cycle.

A single cycle in the Red Head Rapids Formation in the study area is

interpreted as follows:

Stage 1: During a transgression, the open subtidal lithofacies

association (lithofacies A: greyish-green dolomudstone, lithofacies B: skeletal

wackestone, lithofacies C: mottled-nodular skeletal lime mudstone) was

deposited in the subtidal zone under relatively low energy conditions.

Lithofacies A represents more restricted conditions at the onset of the

transgression. The saline mud flat lithofacies association (lithofacies F:

anhydrite) were deposited in the intertidal to supratidal zones of the tidal flat

islands. Arid conditions favoured the formation of evaporite deposits in these

zones. Continuous carbonate production resulted in aggradation and

progradation.

Stage 2: With regression, the open subtidal zone became increasingly

more restricted and more saline due to the arid climate. The saline subtidal

lithofacies association (lithofacies D: massive-laminated dolomudstone and

63 1 1

Figure 7.2. Modified tidal flat island model illustrating deposition of a carbonate-evaporite cycle in the Red Head Rapids Formation in response to relative sea-level fluctuations in an arid climate, based on Pratt et al. (1992). This illustration is vertically exaggerated.

64 1 1

lithofacies E: interlaminated dolomudstone, anhydrite and halite) was deposited

under low energy conditions. These deposits aggraded locally toward sea level

forming tidal flat islands. With subsequent transgression, open-subtidal

conditions were re-established and flooded the saline mud flats.

As a result of relative sea-level fluctuations over time, four shallowing

and brining-upward cycles are formed in the Red Head Rapids Formation.

7.3 Paleogeography Of The Hudson Bay Basin

As discussed in Section 5.3, the cycles recognized in the Red Head

Rapids Formation in the Comeault No. 1, Kaskattama No. 1, Polar Bear C-11

wells have been correlated to the cycles in the Red Head Rapids Formation

exposed at Cape Donovan, Southampton Island. Comparison of the cycles

suggests that the region of the Hudson Bay Lowland was in a basin-margin

position based on the abundance of peritidal lithofacies and the absence of

organic-rich lithofacies and argillaceous lithofacies. Southampton Island is

interpreted to have been situated in a basin-central position in the Late

Ordovician based on the presence of oil shales and argillaceous limestone and

dolostone rocks (cf. Zhang, 2008) and limited evidence for thin evaporites (M.

Nicolas, 2011, pers. comm.).

7.4 Petroleum Source Rock Potential

Based on the Rock Eval™ 6/TOC results, lithofacies A (greyish-green

dolomudstone) in the Red Head Rapids Formation study area has low source

65 1 1

rock potential (refer to Chapter 6). The three samples have low TOC values

suggesting either poor productivity and/or poor preservation of organic matter

(cf. Parrish, 1982). The basin-margin setting interpreted for the study area

during the Late Ordovician may be a significant factor. Salinity changes may

also trigger algal blooms, but oxidizing conditions which would be typical in

many shallow-marine settings would promote oxidation of organic matter (eg.

Parrish, 1982). In comparison, the high TOC values from the oil shales in the

Cape Donovan outcrop on Southampton Island indicate periods of high

productivity and/or good preservation of organic matter (cf. Parrish, 1982) The

interpreted basin-central location for Southampton Island during the Late

Ordovician would have favoured low energy, anoxic deep water.

The low Tmax values in the Red Head Rapids Formation indicate

insufficient burial history (cf. Hunt, 1996) in the study area and Southampton

Island.

7.5 Future Work

This study has laid the foundation for future stratigraphic and organic

petrological and geochemical studies of the Red Head Rapids Formation in the

Hudson Bay Basin. The following outlines recommendations for future work:

1) Additional sedimentologic and biostratigraphic data from wells with

conodonts such as the Pen Island No. 1 and Narwhal 0-58 wells should be

used for stratigraphic correlation across the Hudson Bay Basin. In particular,

66 1 1

the lateral extent and thickness of the lithofacies in the Red Head Rapids

Formation require further detailed examination.

2) More detailed conodont analysis with closer-spaced sampling intervals,

should be carried out for a more precise biostratigraphic correlation in the Red

Head Rapids Formation across the Hudson Bay Basin.

3) Further sedimentology and organic geochemistry of shale intervals in the

other wells located in the Hudson Bay Lowland should be done to further

evaluate the economic potential of the Red Head Rapids Formation in the

Hudson Bay Basin.

67 1 1

CHAPTER 8: CONCLUSION

Detailed sedimentological examination of the Red Head Rapids

Formation in the Comeault No. 1 and Kaskattama No. 1 wells in the

northeastern Manitoba has contributed to an improved understanding of the

depositional origin and source rock potential of the formation. A summary of

the key findings of this study is as follows:

1. The Red Head Rapids Formation is composed of six lithofacies which

are grouped into three lithofacies associations. Lithofacies A (greyish-

green dolomudstone), B (skeletal wackestone) and C (mottled-nodular

skeletal lime mudstone) comprise the open subtidal lithofacies

association. Lithofacies D (massive-laminated dolomudstone) and E

(interlaminated dolomudstone, anhydrite and halite) are grouped as the

saline subtidal lithofacies association. Lithofacies E (anhydrite) is the

saline mud flat lithofacies association.

2. The stacking pattern of the lithofacies associations forms four shallowing

and brining-upward, meter-scale cycles, which are readily recognized in

both wells. A complete cycle consists of the lower, open subtidal

lithofacies association, which is overlain by the saline subtidal lithofacies

association and capped by the saline mud flat lithofacies association.

The tidal flat island model is proposed to explain the shallowing-upward

nature of the individual cycles. Sea-level fluctuations are interpreted to

be the main control for the origin for the stacking of the cycles.

68 1 1

3. The meter-scale cycles identified in the Comeault No. 1 and Kaskattama

No. 1 wells can be correlated to the offshore Polar Bear C-11 well. The

three thin oil shales intervals in the Red Head Rapids Formation in the

Cape Donovan outcrop are correlated to the three intervals of lithofacies

A in the study area. Comparison of the cycles in the three wells and in

the outcrops at Southampton Island suggests that the study area during

the Late Ordovician was in a basin-margin position based on the

abundance of peritidal lithofacies and absence of organic rich lithofacies

and argillaceous lithofacies. Southampton Island is interpreted to have

been situated in a basin-central position, based on the presence of oil

shales and argillaceous rocks.

4. Based on Rock Eval™ 6 analysis, lithofacies A in the Comeault No. 1

and Kaskattama No. 1 wells has low total organic carbon (TOC) values

and low maximum temperature (Tmax) values. The low source rock

potential in the study area is interpreted to be due to (a) poor

productivity and/or poor preservation of organic matter in a basin-margin

setting and (b) insufficient burial history.

69 1 1

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B1

APPENDIX B:

THIN SECTION DESCRIPTIONS

APPENDIX B: THIN SECTION DESCRIPTIONS

B2

Depth Well location

Meter Feet

Sample ID

Lithofacies Lithology Sedimentary Structures

Allochems

Houston Oils et al. Comeault STH #1

471.53

1547 1 C lime wackestone - 10-20%. 100-1200; moderately to poorly sorted; crinoids (50-60%, 120-360); brachiopods (5%, 80-400); fragments (35-45%, 520-640).


464.4 1523.8 2 E dolomudstone and anhydrite

finely laminated. (~3 mm)

-


404.06

1522.5 3 E dolomudstone and anhydrite

finely laminated -


B3


463.51

1520.7 4 F anhydrite massive -

*Note Size range of allochems in micrometers unless specified.

Well location

Depth (m) Matrix Cement Authigentic components (not including cements)

Porosity


471.53 40%. Non-ferroan micrite, planar subhedral to euhedral, finely crystalline dolomite

coarse-blocky and bladed prismatic non-ferroan calcite

- -


464.4 - - 20%. Anhydrite in fractures and voids (0.2 mm); acicular anhydrite (280–480) randomly orientated

--


404.06 - - 20%. Anhydrite in fractures and voids (0.2 mm); acicular anhydrite(280 – 480) randomly orientated

-


B4


463.51 ‐ ‐ 1%. Displacive halite (16, tr), gypsum in secondary porosity (0.4-1 cm, tr), anhydrite (white and translucent) in-filled porosity and fractures

‐

*Note Size range of authigenic components in micrometers unless specified, tr=trace amounts.


B5

Depth Well location

Meter Feet

Sample ID Lithofacies Lithology Sedimentary Structures

Allochems


462.47 1517.3 5 F anhydrite massive -


459.67 1508.1 6 F anhydrite massive -



laminations -


457.78 1501.9 8 B skeletal dolowackestone

massive 45-50%. 800 - 7000; moderately to poorly sorted; tabulate corals (Paleofavosites) (< 1%, 7000); brachiopods (20%, 800-7000); crinoids (50%, 720-2400); bryozoans (15%, 1200-1400). Algal (<5%, 600-2000). Fragmented skeletals (10-15%, 400-2800).



B6

Well location


Porosity


462.47 - anhydrite and dolomite cement

1-3%. Displacive halite (16, tr), gypsum in secondary porosity (0.4-1 cm, tr)

-


459.67 - anhydrite and dolomite cement

<40%. Anhydrite needles (280 – 480) randomly orientated

-


458.54 - blocky calcite cement <40%. Anhydrite needles (280 – 480) randomly orientated

<1%. Interparticle and moldic porosity porosity


457.78 45% micrite

<5%. Anhydrite needles (400-2000), halite crystals in intraparticle pores

<1%. Interparticle and moldic porosity porosity.



B7

Depth Well location

Meter Feet

Sample ID


Allochems


457.41 1500.7 9 B skeletal dolowackestone- floatstone

- 50%. 800 - 7000; moderately to poorly sorted; tabulate corals (Paleofavosites) (<1%, 7000); brachiopods (20%, 800-7000); crinoids (50%, 720-2400); bryozoans (15%, 1200-1400). Algal (<5%, 600-2000). Fragmented Skeletals (10%, 400-2800).


457.02 1499.4 10 B skeletal dolowackestone- floatstone

same as sample 9.



laminations -


447.37 1467.8 12 F anhydrite - -



B8

Well location


Porosity


457.41 20% micrite blocky calcite cement same as sample 8 <1% Interparticle and moldic porosity porosity.


457.02 35% micrite blocky calcite cement same as sample 8 <1% Interparticle and moldic porosity porosity.


449.98 45% micrite - 20%. Anhydrite in fractures and voids (200); acicular anhydrite needles (280–480) randomly orientated

-


447.37 ‐ - 1-5%. Displacive halite (16 µm, tr), gypsum in secondary porosity (0.4-1 cm, tr), anhydrite (white and translucent) filling porosity and fractures

-



B9

Depth (m) Well location

Meter Feet


Allochems


446.93 1466.3 13 B dolomudstone - 40%. Mostly undifferentiated skeletal fragments, crinoids are sparse.


446.11 1463.6 14 C skeletal lime mudstone

thin laminations 50%. 800 - 7000; moderately to poorly sorted; tabulate corals (paleofavosites) (< 1%, 7000); brachiopods (20%, 800-7000); crinoids (50%, 720-2400); bryozoans (15%, 1200-1400); Algal (5%, 600-2000); Fragmented Skeletals (10%, 400-2800).



thin laminations same as sample 14



thin laminations 10-20%. 100-1200; moderately to poorly sorted; crinoids (50-60%, 120-360); brachiopods (5%, 80-400); fragments (35-45%, 520-640).



B10

Well location


Porosity


446.93 45% micrite dolomite and blocky calcite cement

anhydrite needles (1.2 cm) in the matrix, and very fine halite crystals in intraparticle pores, respectively. Millimetre scale fractures filled by celestine

<1%. Interparticle and moldic porosity porosity.


446.11 30% micrite coarse-blocky and bladed prismatic non-ferroan calcite

- <5%. interparticle and moldic porosity.








B11

Depth Well location

Meter Feet


Allochems



- same as sample 14


435.16 1427.7 18 E dolomudstone - -


434.87 1426.8 19 F anhydrite - -


433.61 1422.6 20 F anhydrite -


B12

Well location


Porosity



- <1% interparticle and moldic porosity.


435.16 45% dolomicrite - 20%. Anhydrite in fractures and voids (200); acicular anhydrite needles (280–480) randomly orientated

-


434.87 - - 1-5%. Displacive halite (16, tr), gypsum in secondary porosity (0.4-1 cm, tr), anhydrite (white and translucent) filling porosity and fractures

None


433.61 ‐ ‐ 1-5%. Displacive halite (16, tr), gypsum in secondary porosity (0.4-1 cm, tr), anhydrite (white and translucent) filling porosity and fractures

None



B13

Depth Well location

Meter Feet

Sample ID


Allochems


432.66 1419.5 21 A dolomudstone massive -




423.82 1390.5 23 E dolomudstone, anhydrite, halite

finely laminated (3 mm)

-

Sogepet-Aquitaine Kaskattama Province No.1

699.52 2295.0 24 E dolomudstone, anhydrite, halite


-


B14

Well location


Porosity


432.66 - - - <1%. Interparticle and intraparticle porosity.


432.30 - - - <1%. Interparticle and intraparticle porosity.


423.82 35%-40%. Non-ferroan dolomicrite

10-40% dolomite and anhydrite cement

10-20%. Anhydrite and halite in fractures and voids (mostly 0.2 mm); acicular anhydrite needles (280–480) randomly orientated

-


699.52 35%-40%. Non-ferroan dolomicrite

10-40% dolomite and anhydrite cement

5-15%. Anhydrite and halite in fractures and voids (mostly 0.2 mm); acicular anhydrite needles (280–480) randomly orientated

-

*Note Size range of authigenic components in micrometers unless specified.


B15

Depth (m) Well location

Meter Feet


Allochems


698.90 2293.0 25 E dolostone, anhydrite, halite


-




-




-




-


B16

Well location


Porosity


698.90 30-40%. Non-ferroan dolomicrite

10-40%.Dolomite and anhydrite cement

20-30%. Anhydrite in fractures and voids (0.2 mm); acicular anhydrite needles (280 – 480) randomly orientated

<1%. Intraparticle and vuggy porosity




20%. Anhydrite in fractures and voids (0.2 mm); acicular anhydrite needles (280 – 480) randomly orientated



696.97 35%. Non-ferroan dolomicrite











B17

Depth Well location

Meter Feet


Allochems




692.32 2271.4 30 C dolowackestone massive same as sample 14


694.33 2278.0 31 C dolowackestone massive 5-10%. 100-1200; moderately to poorly sorted; crinoids (50-60%, 120-360); brachiopods (5%, 80-400); fragments (35-45%, 520-640)


685.31 2248.4 32 F anhydrite massive None



B18

Well location


Porosity



None Not distinguishable <1%. Intercrystalline porosity


692.32 -35%. Non-ferroan micrite and dolomicrite, partly dolomitized and planar-subhedral to planar-euhedral, finely crystalline dolomite


3-10%. Planar-euhedral to planar subhedral, finely crystalline dolomite partly replacing matrix (<64, <7%). Anhydrite needles (480-3000, 1-2%) in matrix and interparticle pores, halite (40, tr) in interparticle porosity

<5%. Interparticle (tr) and moldic (60-80 µm, <5%)


694.33 -35%. Non-ferroan micrite and dolomicrite, partly dolomitized and planar-subhedral to planar-euhedral, finely crystalline dolomite


same as sample 30 <5%. Interparticle (tr) and moldic (60-80 µm, <5%)


685.31 - - 1-5%. Displacive halite (16 µm, tr), gypsum in secondary porosity (0.4-1 cm, tr), anhydrite (white and translucent) filling porosity and fractures

None



B19

Depth Well location

Meter Feet

Sample ID


Allochems


683.40 2242.1 33 E dolomudstone, anhydrite and halite

- None



- None



- None



finely laminated 0-10%. Peloids and non-skeletal fragments (16-80, 5-7%). Sub-angular to rounded micritic intraclasts, opaques and/or undifferentiated skeletal fragments (840-1800, 0-3%)



B20

Well location


Porosity



30-40%. Dolomite and anhydrite cement


<1%. intraparticle and vuggy porosity


















B21

Depth Well location

Meter Feet


Allochems


669.28 2195.8 37 A dolomudstone massive None


667.57 2190.2 38 D dolomudstone massive None


667.30 2189.3 39 A dolomudstone massive None


668.12 2192.0 40 E dolomudstone None


B22

Well location Depth (m) Matrix Cement Authigentic components (not including cements)

Porosity



None Not distinguishable <1%. Intercrystall-ine


667.57 85-100%. Non-ferroan dolomitic aphanocrystalline micrite

3-15%. Anhydrite and dolomite cement in interparticle pores

None <1%. Interparticle (tr), vuggy (tr



None Not distinguishable <1%. Intercrystalline



10-40% dolomite, anhydrite cement




C1

APPENDIX C:

X-RAY DIFFRACTION RESULTS

(RESULTS ALSO IN ENCLOSED CD)

APPENDIX C: X-RAY DIFFRACTOGRAMS

C2

Comeault No. 1 well, 423.30 m, 1418.3 ft, Dolomite


C3

Comeault No. 1 well, 432.66 m, 1419.5 ft, Dolomite


C4

Comeault No. 1 well, 446.93 m, 1466.3 ft, Celestine


C5

Kaskattama No. 1, 669.28 m, 2195.8 ft, Anhydrite and halite

D1

APPENDIX D:

ROCK EVALTM 6 RESULTS

APPENDIX D: ROCK EVALTM 6 RESULTS

D2

Well Depth (ft.)

Sample Qty S1 S2 PI S3 Tmax Tpeak S3CO PC (%)

TOC RC %

HI OICO OI

Standard 0 9107 70.4 0.71 12.12 0.06 0.60 442 481 0.19 0.10 5.05 3.95 240 4 12 Houston Oils et al. Comeault STH No. 1

1418 C-1418.3 70.6 0.06 0.24 0.19 0.44 431 470 0.01 0.04 0.37 0.33 65 3 119

Houston Oils et al. Comeault STH No. 1

1389 106-10-HBL

- 0.07 0.19 0.03 0.39 415 450 0.03 0.04 0.42 0.38 45 7 93

Sogepet Aquitaine Province

Kaskattama No. 1

2195 K-2195.8 70.6 0.10 0.81 0.11 0.29 440 479 0.02 0.09 0.34 0.25 238 6 85

APPENDIX D: ROCK EVALTM 6 RESULTS

D3

Well Depth (ft.) MINC % S4CO S4CO2 RCCO(%) S4CO2 S5aCO2 S5bCO2 KFID RCCO2

(%) Standard 0 4.4 18.5 115.8 0.79 0.0 0.0 0.0 1166 3.16 Houston Oils et al. Comeault STH No. 1

1418 12.9 0.3 11.7 0.01 0.0 0.0 0.0 1166 0.32

Houston Oils et al. Comeault STH No. 1

1389 5.72 - - - - - - - -

Sogepet Aquitaine Province

Kaskattama No. 1

2195 2.9 0.1 9.1 0.00 0.0 0.0 0.0 1166 0.25

wong, 2011 (b.sc.g.sc.hons.thesis-final).compressed

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