new insights for pdf v1
TRANSCRIPT
![Page 1: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/1.jpg)
New Insights From Old Data:
Examples from Historically Significant Tasmanian Ore Deposits
Tony WebsterMining Geoscience
December 2016
![Page 2: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/2.jpg)
WHAT CAN A HOLE TELL US ABOUT ORE DEPOSIT GEOLOGY?
![Page 3: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/3.jpg)
INTRODUCTION - PHILOSOPHY
The best way to understand orebodies is to understand their litho-structural architecture.
– Better-understand the ones we know about
There are new things to be understood about the great (or maybe not-so-great) deposits and mining fields.
– They have often been misunderstood by earlier workers, and poor theories have been perpetuated by a lack of geological context – understanding of the deposit architecture - for more detailed research.
Original source: Lionore P/L
2D and 3D models of mined deposits can utilise the rich geoscientific data collected as they were extracted & can help to solve this problem
![Page 4: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/4.jpg)
AIM OF PROJECT - HISTORIC MINE GEOLOGICAL MODEL LIBRARY
Build accurate litho-structural models of historically and economically significant ore deposits
- Ore/grade controls, - structural evolution and deformation
history
Develop greater understanding of the geology of key type examples
- e.g Broken Hill
Compile and interpret the mine - and near-mine geological data
- Identify the controls on economic mineralisation & provide a context for efficient near mine exploration and mine design
Information dates from the mid- 19thC to the present.
Henderson Molybdenum Mine Block Cave Glory Hole. Colorado USAhttp://en.wikipedia.org/wiki/Henderson_molybdenum_mine
A firm context for research into the structural evolution of a deposit and its
genesis.
Cost-effective and accurate brownfields exploration
![Page 5: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/5.jpg)
AIM OF PROJECT – BEYOND ECONOMIC GEOLOGY
Developing a ‘library’ of deposit models from across Australia.
Will eventually be released online.
History: Increase understanding of the historical & technological development of the Australian mining industry
- regional mining towns that are such a significant part of the nations history
Historical archaeology: how these historically important mines were developed- in earliest phases.
- Document the locations of underground workings, & the archaeological evidence that is likely to remain
![Page 6: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/6.jpg)
EXAMPLES DISCUSSED
1. Mt Farrell Ag-Pb-Zn
2. Iron Blow/North Lyell Cu-Au
3. New Golden Gate – Au
Some of the most historic Tasmanian deposits (mines)
![Page 7: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/7.jpg)
Mt Farrell Field:New North Mt Farrell Mine
Mt Farrell Mine
http://blog.mailasail.com/beezneez/3112
![Page 8: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/8.jpg)
• Ag-Pb deposit (also Cu and barite in
some mines)
• Focus on the two main producing
mines – a single system
– North Mt Farrell (1899-1933) and
– New North Mt Farrell (1934-1973).
• Hosted in Cambrian laminated
shale, volcaniclastic sandstone
(“tuffs”), greywackes and minor
lava (the "Farrell Slate") which
strike NNE and dip steeply W.
ABOUT THE MT FARRELL (TULLAH) FIELD
Solomon, (1965); McNeill and Corbett, (1989)
![Page 9: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/9.jpg)
Genesis: Current – Devonian vein mineralisation
Originally suggested to be related to intrusion of Devonian granitoids (Solomon, 1965)
Isotopic data indicated a Cambrian seawater source, with possible minor magmatic input for sulphur (Polya, 1981; Solomon et al., 1969)
+ lack of an obvious granitic source,
+ common deformation of galena, and lack of wall rock alteration, led Collins et al. (1981) to suggest that the mineralisation is probably remobilised volcanogenic massive sulfide.
Mineralogy is similar to Pb-Zn deposits associated with Devonian granites (Polya, et al., 1986), and the lead isotope data of Gulson and Porritt (1987) indicate that the lead is post-Cambrian
The Murchison Lode sulphur isotopes indicate significant Devonian sulphur content (Polya, et al., 1986) - with Post-Cambrian lead isotope ratios (Gulson and Porritt, 1987), suggest formation as Devonian vein style mineralisation.
CURRENT THINKING - GENETIC MODEL
From McNeill and Corbett, (1989)
![Page 10: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/10.jpg)
RAW INFORMATION
![Page 11: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/11.jpg)
NEW NORTH MT FARRELL
Workings
![Page 12: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/12.jpg)
NEW NORTH MT FARRELL
Mapped Faults
![Page 13: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/13.jpg)
NEW NORTH MT FARRELL
Mapped Lodes
![Page 14: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/14.jpg)
NEW NORTH MT FARRELL
Lodes – Long Sections (stoped)
![Page 15: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/15.jpg)
NEW NORTH MT FARRELL
Volcaniclastics
![Page 16: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/16.jpg)
NEW NORTH MT FARRELL
Mapped bedding and foliation trends
![Page 17: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/17.jpg)
NEW NORTH MT FARRELL - STRUCTURE Level Plan – 2 Level
![Page 18: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/18.jpg)
NEW NORTH MT FARRELL - STRUCTURE Level Plan – 2 Level
![Page 19: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/19.jpg)
NORTH MT FARRELL
North Mt Farrell Workings
![Page 20: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/20.jpg)
• Spatial and geometric association of ore shoots with strongly folded and transposed ‘volcaniclastic’ units.
• Plunge sub-parallel to the plunge of the folded volcanoclastic unit
• Lodes hosted within the transposed limbs of isoclinal folds in the Farrell Slate – lodes are structurally hosted (but rarely faults).
• Association with folds suggests remobilisation and lode formation during deformation (folding)
ADDITIONAL INFORMATION FROM THE MODELLING
![Page 21: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/21.jpg)
Mt Lyell FieldIron Blow, South Lyell &
North Lyell
![Page 22: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/22.jpg)
ABOUT
• Pyrite, copper, silver, gold deposits (plus Pb-Zn)
• Hosted in Mt Read Volcanics– the Lyell Schist
• Remobilisation of metals during intense deformation
• Though some suggest it is a hybrid porphyry system
![Page 23: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/23.jpg)
CURRENT THINKING - GENETIC MODEL
• A Cambrian subsea floor replacement style VHMS deposit
• Hosted in Mt Read Volcanics –the Lyell Schist
– Suggested that it is a hybrid porphyry system
• Some remobilisation of metals during later deformation –focussed at structural contact with younger Owen Conglomerate – ‘bonanza’ shoots
Gregory, (1905)
![Page 24: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/24.jpg)
RAW INFORMATION
![Page 25: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/25.jpg)
Iron Blow & South Lyell
Corbett, 2001
![Page 26: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/26.jpg)
IRON BLOWLong Section – Through Plane of No 4 Tunnel
Note: grid scale is in FEET
Iron Blow Outcrop
![Page 27: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/27.jpg)
IRON BLOW MODELLong Section – Through Plane of No 4 Tunnel
View approximately to north
![Page 28: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/28.jpg)
IRON BLOW MODELOriginal Topography and ‘Iron Blow’ Outcrop
View approximately to north
![Page 29: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/29.jpg)
IRON BLOW MODELNo 4 Tunnel and Early Workings
View approximately to north
![Page 30: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/30.jpg)
IRON BLOW MODELWorkings – to No 9 Level
View approximately to north
![Page 31: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/31.jpg)
IRON BLOW MODELIron Blow Orebody – Pyrite-Cu-Au
View approximately to north
![Page 32: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/32.jpg)
IRON BLOW MODELSouth Lyell Orebody – Pyrite-Cu-Au
View approximately to north
Inset: view to northeast
![Page 33: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/33.jpg)
IRON BLOW MODELConglomerate Contact
View approximately to north
Inset view: approximately southwest
![Page 34: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/34.jpg)
IRON BLOW MODELConglomerate Contact
View approximately to north
![Page 35: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/35.jpg)
IRON BLOW MODELConglomerate Contact
View approximately to northFault offset of South Lyell Orebody from Iron Blow
Orebody?
![Page 36: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/36.jpg)
IRON BLOW MODEL‘Bonanza’ Shoots
View approximately to north
On the eastern (footwall) of the pyrite orebody, at the boundary between the sulphide oreand the lower continuation of the haematite of the “Iron Blow”
850 tons of ore - copper glance (redruthite), bornite, “fahlore” and argentite (silver glance).
Haematite and barite, with rich ore between this and the wall and on the floor
Richest ore was chalcopyrite and argentite or stromeyerite. Bornitic ore often contained asmuch as 5% Ag and often had “arsenical fahlore” (tennantite).
Also abundant chalcopyrite containing from 200 - 400 oz Ag/ton.
Daly, (1901) and Gregory, (1905)
![Page 37: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/37.jpg)
IRON BLOW MODEL‘Bonanza’ Shoots
View approximately to north
On the eastern (footwall) of the pyrite orebody, at the boundary between the sulphide oreand the lower continuation of the haematite of the “Iron Blow”
850 tons of ore - copper glance (redruthite), bornite, “fahlore” and argentite (silver glance).
Haematite and barite, with rich ore between this and the wall and on the floor
Richest ore was chalcopyrite and argentite or stromeyerite. Bornitic ore often contained asmuch as 5% Ag and often had “arsenical fahlore” (tennantite).
Also abundant chalcopyrite containing from 200 - 400 oz Ag/ton.
Daly, (1901) and Gregory, (1905)
The discovery of this shoot provided most of the capital to develop the mine.
![Page 38: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/38.jpg)
IRON BLOW MODEL‘Bonanza’ Shoots
View approximately to north
Inset view: approximately southwest
![Page 39: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/39.jpg)
North Lyell
Corbett, 2001
![Page 40: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/40.jpg)
NORTH LYELL MODELBase Plan
![Page 41: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/41.jpg)
NORTH LYELL MODELStoped Orebodies
![Page 42: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/42.jpg)
NORTH LYELL MODELContacts – Lyell Schist and Conglomerate
![Page 43: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/43.jpg)
NORTH LYELL MODEL
Transposed tight to isoclinal fold – looking down-dip
Orebody Geometry
![Page 44: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/44.jpg)
ADDITIONAL INFORMATION FROM THE MODELLING
• The Mt Lyell mineralised system is structurally dislocated,
– was probably once a single continuous stratabound zone of alteration and mineralisation – put it back together
• Complexly folded (very tight to isoclinal) and transposed
– probably structurally differentiated by cleavage formation – particularly North Lyell
• Dislocated by NW-trending faults
• High grade Cu-Ag shoots located at structural contact with conglomerate – remobilised copper and silver (exploration target?)
![Page 45: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/45.jpg)
ADDITIONAL INFORMATION FROM THE MODELLING
Some Exploration Questions
• Have all dislocated segments of the copper mineralisation been located between North Lyell and the Iron Blow (e.g. beyond the South Lyell)?
• Where is the lead-zinc? This part of the system is under-represented - seems largely to be missing – does it remain to be found in dislocated segments?
• The style of deformation – dislocation, folding and foliation/differentiation is very similar to that of the Hercules VHMS, near Rosebery
Explore as a single giant VHMS and sub-seafloor replacement system –
But first understand the whole system architecture – especially the structure
![Page 46: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/46.jpg)
TAKE HOME MESSAGE
• Maintaining data from even mined out deposits is so important – you may never know when it is needed
• Why geological surveys are so important as data repositories
• Companies should maintain mine data – it is an asset
and
![Page 47: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/47.jpg)
WHAT CAN A HOLE TELL US ABOUT ORE DEPOSIT GEOLOGY?
The data that came from that hole – the mined orebodies (and their wall rocks) – may be the key to any future brownfields
exploration, mining feasibility studies, and ore deposit research
![Page 48: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/48.jpg)
NOTE
Models will be available to anyone that wants them
Some of the models built to date include:
Broken Hill Mining Field, NSW.Zeehan Mining Field, Tasmania.ABH Consols Mine (Broken Hill), NSWMt Morgan, Queensland.The New Golden Gate Mine - Mathinna, Tasmania.The Iron Blow and North Lyell Mines, Tasmania.The Mt Farrell Mining Field - Tullah, TasmaniaThe Botallack Mine, Cornwall, UK.Coal mines – saltwater riverThe Blackstone Hill coal mining area, Ipswich, Queensland.Various Tennant Creek and Cloncurry depositsHannans North Mine
The model library will eventually be released online.
It is made possible by the academic licence software support to CODES/UTAS by ARANZ Geo (Leapfrog Geo software) and by Maptek (Vulcan).
![Page 49: New insights for pdf v1](https://reader031.vdocuments.us/reader031/viewer/2022021422/5899c6411a28ab45548b60c1/html5/thumbnails/49.jpg)
ACKNOWLEDGEMENTS
ARANZ Geo
Maptek
Research software
Mineral Resources Tasmania Digital archival data