Studies ofVHMS-related alteration: geochemical and … · 2012-06-25 · data base includes 1730...

AY 998

F L

PO

Australian Mineral Industries Research Association LimitedACN 004 448 266

Studies of VHMS-related

alteration: geochemical and

mineralogical vectors to ore

P439

~"CODES SRC

AY 998

Australian Mineral Industries Research Association LimitedACN 004 448 266

Studies of VHMS-related

alteration: geochemical and

mineralogical vectors to ore

P439

~..CODES SRC

Studies of VHMS-related alteration:geochemical and mineralogical vectors to ore

EXECUTIVE

SUMMARY

AMIRAlARC project P439

Volume 1, Final ReportMay 1998

009'

CODES SRC

Studies of VHMS-related alteration:geochemical and mineralogical vectors to ore

EXECUTIVE

SUMMARY

AMIRAlARC project P439

Volume 1, Final ReportMay 1998

009'

CODES SRC

ii

Centre for Ore Deposit Research,School of Earth Sciences,University of Tasmania,GPO Box 252-79,Hobart, Tasmania,

Australia 7001

http://www.geol.utas.edu.au/codes

another Pongratz Production 1998

ii

Centre for Ore Deposit Research,School of Earth Sciences,University of Tasmania,GPO Box 252-79,Hobart, Tasmania,

Australia 7001

http://www.geol.utas.edu.au/codes

another Pongratz Production 1998

iii

Contents

Introduction 1

Summary of geochemical and mineralogical vectors to ore, based on the seven case studies in P439

- Ross Large, Bruce GemmelI and Walter Herrmann 5

Alteration halo model for the Rosebery VHMS deposit, western Tasmania

- Ross Large, Rod Alien, Mike Blake and WaIter Herrmann 13

,Alteration model for the HelIyer VHMS deposit, western Tasmania

- J. Bruce GemmelI and RusselI Fulton 17

Mt Julia-Henty gold mine: Summary of alteration study - Tim Callaghan 21

Alteration halo model for the Zone 96 volcanogenic gold deposit, Henty gold mine,

western Tasmania - Jason Beckton 27

Alteration zonation and geochemical dispersion at the Western Tharsis deposit, Mt LyelI,

Tasmania: a summary - David Huston and Julianne Kamprad 29

Alteration halo of the Thalanga VHMS deposit, north Queensland - Holger Paulick 33

Alteration halo model for the Highway-Reward sub-seafloor replacement deposit,

Mount Windsor Subprovince, Queensland - Mark G. Doyle 39

Alteration case study of the Gossan Hill VHMS deposit - Robina Sharpe and Bruce GemmelI 43

Carbonate alteration at the Rosebery mine: The relationships between alteration texture,

paragenesis, chemistry of carbonate minerals, and distance to ore - Rodney L. Alien,

Michael Blake and Ross R. Large 47

A molar element ratio analysis of lithogeochemical samples from the footwall andesite,

Hellyer VHMS district, Tasmania, Australia - Clifford R. Stanley and J. Bruce GemmelI 53

Chlorite alteration associated with syn-volcanic granites and Cu-Au mineralisation:

A pilot study along the Jukes Road - Bill Wyman 57

cont.

CODES: AMIRA/ ARC Project P439­Studies of VHMS-related alteration: geochemical and

mineralogical vectors to ore. May 1998~CODES SRC

iii

Contents

Introduction 1

Summary of geochemical and mineralogical vectors to ore, based on the seven case studies in P439

- Ross Large, Bruce GemmelI and Walter Herrmann 5

Alteration halo model for the Rosebery VHMS deposit, western Tasmania

- Ross Large, Rod Alien, Mike Blake and WaIter Herrmann 13

,Alteration model for the HelIyer VHMS deposit, western Tasmania

- J. Bruce GemmelI and RusselI Fulton 17

Mt Julia-Henty gold mine: Summary of alteration study - Tim Callaghan 21

Alteration halo model for the Zone 96 volcanogenic gold deposit, Henty gold mine,

western Tasmania - Jason Beckton 27

Alteration zonation and geochemical dispersion at the Western Tharsis deposit, Mt LyelI,

Tasmania: a summary - David Huston and Julianne Kamprad 29

Alteration halo of the Thalanga VHMS deposit, north Queensland - Holger Paulick 33

Alteration halo model for the Highway-Reward sub-seafloor replacement deposit,

Mount Windsor Subprovince, Queensland - Mark G. Doyle 39

Alteration case study of the Gossan Hill VHMS deposit - Robina Sharpe and Bruce GemmelI 43

Carbonate alteration at the Rosebery mine: The relationships between alteration texture,

paragenesis, chemistry of carbonate minerals, and distance to ore - Rodney L. Alien,

Michael Blake and Ross R. Large 47

A molar element ratio analysis of lithogeochemical samples from the footwall andesite,

Hellyer VHMS district, Tasmania, Australia - Clifford R. Stanley and J. Bruce GemmelI 53

Chlorite alteration associated with syn-volcanic granites and Cu-Au mineralisation:

A pilot study along the Jukes Road - Bill Wyman 57

cont.

CODES: AMIRA/ ARC Project P439­Studies of VHMS-related alteration: geochemical and

mineralogical vectors to ore. May 1998~CODES SRC

iv

Use of immobile elements and chemostratigraphy to determine precursor volcanics- Walter Herrmann 61

Development and use of the alteration box plot - Ross Large 63

Application of PIMA and FTIR spectometry to VHMS alteration studies - Walter Herrmann,

Michael Blake, Mark Doyle, David Huston and Julianne Kamprad 65

P439 geochemical whole-rock and mineral database - Michael D. Blake 69

Discrimination of diagenetic, hydrothermal and metamorphic alteration

- Rodney L. Allen, Cathryn C. Gifkins, Ross Large and WaIter Herrmann 73

Geochemical modelling of low temperature (5° to 150°C) seawater-andesite interaction:

Implications for regional alteration assemblages in VHMS districts- Stephen B. Bodon and David R. Cooke 79

Application of ironstone geochemistry to exploration for VHMS deposits in the

Mt Windsor Volcanic Belt - Garry Davidson : 81

Volcanic facies and alteration - J McPhie 85

Alteration in different glassy volcanics with emphasis on early diagenetic alteration;

a case study from the Mount Black Volcanics - Cathryn C Gifkins 91

Influence of volcanic fades on hydrothermal and diagenetic alteration: Evidence from the

Highway-Reward deposit, Mount Windsor Subprovince, Queensland - Mark G. Doyle 95

Bibliography 101

iv

Use of immobile elements and chemostratigraphy to determine precursor volcanics- Walter Herrmann 61

Development and use of the alteration box plot - Ross Large 63

Application of PIMA and FTIR spectometry to VHMS alteration studies - Walter Herrmann,

Michael Blake, Mark Doyle, David Huston and Julianne Kamprad 65

P439 geochemical whole-rock and mineral database - Michael D. Blake 69

Discrimination of diagenetic, hydrothermal and metamorphic alteration

- Rodney L. Allen, Cathryn C. Gifkins, Ross Large and WaIter Herrmann 73

Geochemical modelling of low temperature (5° to 150°C) seawater-andesite interaction:

Implications for regional alteration assemblages in VHMS districts- Stephen B. Bodon and David R. Cooke 79

Application of ironstone geochemistry to exploration for VHMS deposits in the

Mt Windsor Volcanic Belt - Garry Davidson : 81

Volcanic facies and alteration - J McPhie 85

Alteration in different glassy volcanics with emphasis on early diagenetic alteration;

a case study from the Mount Black Volcanics - Cathryn C Gifkins 91

Influence of volcanic fades on hydrothermal and diagenetic alteration: Evidence from the

Highway-Reward deposit, Mount Windsor Subprovince, Queensland - Mark G. Doyle 95

Bibliography 101

Introduction

Project objectives P439

The five project objectives of P439 as outlined in theoriginal research proposal are:

• To characterise the mineralogy and geochemistryfor the various styles of hydrothermal alteration

throughout the Mount Read Volcanics (MRV) andthe Mount Windsor Volcanics (MWV). This will

be based on mapping supported by whole-rockand trace element geochemistry, mineral

chemistry, REE and stable isotope geochemistry.

• To determine the relationship between geo­chemical alteration patterns and sub-volcanicintrusions that are coeval with VHMS formation.

• To undertake case studies of alteration halos relatedto specific VHMS deposits with particularemphasis on hangingwall alteration, and therelationship between alteration patterns andvolcanic fades.

• To develop a set of vectors towards ore based onthe regional studies and ore deposit specific studiesthat can be applied in the exploration for VHMS

deposits in submarine volcanic sequences through­out Australia. The vector matrix will includewhole-rock, trace element, mineral chemistry, REE,isotope and volcanic fades factors.

• To produce a book on "Alteration mineralogy,geochemistry and textures in volcanics related toVHMS deposits" as a follow-up to the successfulpublication by CODES of "Volcanic Textures".

At the first progress meeting (April 1995), and in

subsequent meetings, a number of sponsors em­phasised the importance of including studies onmineral chemistry in both the regional and deposit

case studies. In response to this request the work onmineral chemistry was expanded in the latter part of

the project at the expense of some of the plannedisotQpic and REE research.

Research framework

This project involved a multidisdplinary approachutilising studies in volcanic fades analysis, volcanic

petrology and geochemistry, with alteration andmineralisation to develop models for the composition,

style and extent of alteration throughout submarine

volcanic environment hosting VHMS deposits. The

venn diagram below outlines the relationshipsbetween the different modules of the project.

Petro­graphyandgeochemist

Alteration andmineralisation

CODES; AMIRA/ARC Project P439 ­Studies of VHM5-related alteration: geochemical and

mineralogical vectors to ore. May 199800•CODES SRC

Introduction

Project objectives P439

The five project objectives of P439 as outlined in theoriginal research proposal are:

• To characterise the mineralogy and geochemistryfor the various styles of hydrothermal alteration

throughout the Mount Read Volcanics (MRV) andthe Mount Windsor Volcanics (MWV). This will

be based on mapping supported by whole-rockand trace element geochemistry, mineral

chemistry, REE and stable isotope geochemistry.

• To determine the relationship between geo­chemical alteration patterns and sub-volcanicintrusions that are coeval with VHMS formation.

• To undertake case studies of alteration halos relatedto specific VHMS deposits with particularemphasis on hangingwall alteration, and therelationship between alteration patterns andvolcanic fades.

• To develop a set of vectors towards ore based onthe regional studies and ore deposit specific studiesthat can be applied in the exploration for VHMS

deposits in submarine volcanic sequences through­out Australia. The vector matrix will includewhole-rock, trace element, mineral chemistry, REE,isotope and volcanic fades factors.

• To produce a book on "Alteration mineralogy,geochemistry and textures in volcanics related toVHMS deposits" as a follow-up to the successfulpublication by CODES of "Volcanic Textures".

At the first progress meeting (April 1995), and in

subsequent meetings, a number of sponsors em­phasised the importance of including studies onmineral chemistry in both the regional and deposit

case studies. In response to this request the work onmineral chemistry was expanded in the latter part of

the project at the expense of some of the plannedisotQpic and REE research.

Research framework

This project involved a multidisdplinary approachutilising studies in volcanic fades analysis, volcanic

petrology and geochemistry, with alteration andmineralisation to develop models for the composition,

style and extent of alteration throughout submarine

volcanic environment hosting VHMS deposits. The

venn diagram below outlines the relationshipsbetween the different modules of the project.

Petro­graphyandgeochemist

Alteration andmineralisation

CODES; AMIRA/ARC Project P439 ­Studies of VHM5-related alteration: geochemical and

mineralogical vectors to ore. May 199800•CODES SRC

The research was undertaken at the regional scaleand the deposit scale in order to develop criteriauseful for both regional exploration and mine scaleexploration. The regional studies concentrated in theMt Read Volcanics with lesser work in the MtWindsor Volcanics. The emphasis was (a) todetermine the relationship between volcanic fadesand alteration, and (b) to develop criteria todistinguish amongst diagenetic alteration, meta­morphic-related alteration and hydrothermalalteration (VHMS related). The deposit case studiesincluded research at Mt Lyell, Hellyer, Rosebery andHenty in the Mt Read Volcanics; Thalanga andHighway Reward in the Mt Windsor Volcanics andGossan Hill in the Murcmson Volcanics (WA). Theemphasis in the deposit studies was (a) to map outalteration assemblages and zonation, (b) relatealteration mineralogy and geochemistry, (c) investi­gate trace element halos, and (d) to study variationsin mineral chemistry and their relationship toalteration zonation. Because considerable researchhas been published about VHMS footwall alteration,then the focus of the P439 deposit studies was onhangingwall alteration. Our ultimate objective wasto combine the regional and deposit scale studies tocharacterise hydrothermal alteration and develop

vectors to ore.

Achievements of project

This project has made a major advance in ourunderstanding and interpretation of alteration insubmarine volcanics related to VHMS hydrothermalsystems. The prindple achievements listed in theorder that they appear in this final report are givenbelow.

1. Detailed halo alteration models have beendeveloped for the following seven VHMSdeposits; Hellyer, Rosebery, Henty, WesternTharsis, Thalanga, Highway-Reward and GossanHill.

Each model includes a set of criteria and vectorsthat are useful for regional and mine scaleexploration. This is the first time that a set ofVHMS alteration models has been presented

which include volcanic fades, chemostrati­graphy, lithogeochemistry, alteration zonation,halo geochemistry, mineral chemistry andvectors to ore.

2. The deposit case study reports (Volume 2)include a series of Alteration Data Sheets whichcombine geological, geochemical, textural andmineralogical information, including photos onthe one page, to allow comparison of the maincharacteristics of alteration. This format wasdeveloped during the project and emphasisesthe advantages of a multidisdplinary approachin the study of alteration.

3. An in-depth evaluation of the application ofPIMA to alteration studies around VHMSdeposits has been completed with emphasis onthe spectral characteristics of muscovite and theirrelationship to VHMS deposits (Western Tharsis,Roseb~ry and Highway-Reward). This workcombines PIMA spectral data, with micro-probemineral chemistry, whole-rock chemistry andthin section petrography. No study of this typehas been previously completed for VHMSdeposits.

4. A set of criteria have been developed to dis­tinguish diagenetic alteration, metamorphicalteration and hydrothermal (VHMS-related)alteration in submarine volcanics. The criteriacombine studies on volcanic fades, volcanictextures, petrology and lithogeochemistry.

5. An alteration box plot has been developed andtested, which enables comparison of alterationmineralogy with geochemistry to provide aclassification of alteration fades related to VHMSsystems.

6. A Pearce element ratio analysis of altered andunaltered rock compositions within the andesiticfootwall to the Hellyer VHMS deposit wasrevealed several new concepts regarding thehydrothermal alteration. In addition, newinnovative exploration vectors have beendeveloped.

The research was undertaken at the regional scaleand the deposit scale in order to develop criteriauseful for both regional exploration and mine scaleexploration. The regional studies concentrated in theMt Read Volcanics with lesser work in the MtWindsor Volcanics. The emphasis was (a) todetermine the relationship between volcanic fadesand alteration, and (b) to develop criteria todistinguish amongst diagenetic alteration, meta­morphic-related alteration and hydrothermalalteration (VHMS related). The deposit case studiesincluded research at Mt Lyell, Hellyer, Rosebery andHenty in the Mt Read Volcanics; Thalanga andHighway Reward in the Mt Windsor Volcanics andGossan Hill in the Murcmson Volcanics (WA). Theemphasis in the deposit studies was (a) to map outalteration assemblages and zonation, (b) relatealteration mineralogy and geochemistry, (c) investi­gate trace element halos, and (d) to study variationsin mineral chemistry and their relationship toalteration zonation. Because considerable researchhas been published about VHMS footwall alteration,then the focus of the P439 deposit studies was onhangingwall alteration. Our ultimate objective wasto combine the regional and deposit scale studies tocharacterise hydrothermal alteration and develop

vectors to ore.

Achievements of project

This project has made a major advance in ourunderstanding and interpretation of alteration insubmarine volcanics related to VHMS hydrothermalsystems. The prindple achievements listed in theorder that they appear in this final report are givenbelow.

1. Detailed halo alteration models have beendeveloped for the following seven VHMSdeposits; Hellyer, Rosebery, Henty, WesternTharsis, Thalanga, Highway-Reward and GossanHill.

Each model includes a set of criteria and vectorsthat are useful for regional and mine scaleexploration. This is the first time that a set ofVHMS alteration models has been presented

which include volcanic fades, chemostrati­graphy, lithogeochemistry, alteration zonation,halo geochemistry, mineral chemistry andvectors to ore.

2. The deposit case study reports (Volume 2)include a series of Alteration Data Sheets whichcombine geological, geochemical, textural andmineralogical information, including photos onthe one page, to allow comparison of the maincharacteristics of alteration. This format wasdeveloped during the project and emphasisesthe advantages of a multidisdplinary approachin the study of alteration.

3. An in-depth evaluation of the application ofPIMA to alteration studies around VHMSdeposits has been completed with emphasis onthe spectral characteristics of muscovite and theirrelationship to VHMS deposits (Western Tharsis,Roseb~ry and Highway-Reward). This workcombines PIMA spectral data, with micro-probemineral chemistry, whole-rock chemistry andthin section petrography. No study of this typehas been previously completed for VHMSdeposits.

4. A set of criteria have been developed to dis­tinguish diagenetic alteration, metamorphicalteration and hydrothermal (VHMS-related)alteration in submarine volcanics. The criteriacombine studies on volcanic fades, volcanictextures, petrology and lithogeochemistry.

5. An alteration box plot has been developed andtested, which enables comparison of alterationmineralogy with geochemistry to provide aclassification of alteration fades related to VHMSsystems.

6. A Pearce element ratio analysis of altered andunaltered rock compositions within the andesiticfootwall to the Hellyer VHMS deposit wasrevealed several new concepts regarding thehydrothermal alteration. In addition, newinnovative exploration vectors have beendeveloped.

7. Preliminary thermodynamic modelling of lowtemperature seawater-volcanic rock interactionhas been completed, and demonstrates the value

of this approach in determining the temperatureand fluid chemical controls on diagenetic and

hydrothermal alteration.

8. A data base of whole rock and trace element

geochemistry for samples from the Mt ReadVolcanics, Mt Windsor Volcanics and the seven

ore deposit case studies has been compiled. Thedata base includes 1730 rock analyses (thisproject), 2845 MRV rock analyses from othersources (Tas Uui, MRT and Pasminco), and 1020microprobe mineral analyses from the depositstudies. The data base is provided to all sponsorson a compact disc located in the back envelope

of this report (Volume 1).

9. A study of ironstone geochemistry, includingREE and isotopes has shown the application ofthis approach to exploration in the Mt Windsor

Volcanics.

10. Controls on both diagenetic alteration and

hydrothermal alteration by volcanic fades andvolcanic textures has been evaluated and shown

to be critically important, especially at the

diagenetic stage. This work includes regionalstudies especially the Mt Black Volcanics, and

focussed research at Rosebery and Highway­Reward.

This report

The final Report for P439 is divided into four volumes:

Vol. 1: Executive SummaryVol. 2: Ore Deposit case studies and related

researchVol. 3: Regional studies and volcanic facies

controls.Vol. 4: Field meeting guide, Mt Windsor Volcanic

Belt.

Acknowledgements

This project has been supported by the followingcompanies and organisations:

Aberfoyle Resources Limited

Copper Mines of Tasmania

Denehurst Limited

Mineral Resources Tasmania

Normandy Exploration

Pasminco ExplorationQueensland Metals Corporation Ltd

RGC ExplorationRio Tinto Exploration

On behalf of the research team I would like tothank all the company representatives, collaboratorsand AMIRA for their support and scientificinteraction throughout this three year program. In

par~cularwe are indebted to those companies thatprovided access to their deposits for the case studies:RGC, Pasminco, Murchison Zinc, Copper Mines ofTasmania and Aberfoyle.

This project would not have been possible withoutthe very significant contributions by a number of

dedicated and hardworking postgraduate students:Catherine Gifkins, Robina Sharpe, Mark Doyle,

Holger Paulick, Bill Wyman and Russell Fulton.Thanks also for the tireless work of Mike Blake in

organising the alteration data sheets, and to Nilar

Hlaing for printing and collating the papers. As usual

June Pongratz has done a great job in coordinatingand producing this final report.

We hope that the final outcome of this project is

the discovery of a new VHMS deposit in the nearfuture.

U~__"'4

Ross R. LargeDirectorCentre for Ore Deposit Research.

CODES: AMIRA/ARC Project P439­Studies of VHMS-related alteration: geochernical and

mineralogical vectors to ore. May 199800•CODES SRC

7. Preliminary thermodynamic modelling of lowtemperature seawater-volcanic rock interactionhas been completed, and demonstrates the value

of this approach in determining the temperatureand fluid chemical controls on diagenetic and

hydrothermal alteration.

8. A data base of whole rock and trace element

geochemistry for samples from the Mt ReadVolcanics, Mt Windsor Volcanics and the seven

ore deposit case studies has been compiled. Thedata base includes 1730 rock analyses (thisproject), 2845 MRV rock analyses from othersources (Tas Uui, MRT and Pasminco), and 1020microprobe mineral analyses from the depositstudies. The data base is provided to all sponsorson a compact disc located in the back envelope

of this report (Volume 1).

9. A study of ironstone geochemistry, includingREE and isotopes has shown the application ofthis approach to exploration in the Mt Windsor

Volcanics.

10. Controls on both diagenetic alteration and

hydrothermal alteration by volcanic fades andvolcanic textures has been evaluated and shown

to be critically important, especially at the

diagenetic stage. This work includes regionalstudies especially the Mt Black Volcanics, and

focussed research at Rosebery and Highway­Reward.

This report

The final Report for P439 is divided into four volumes:

Vol. 1: Executive SummaryVol. 2: Ore Deposit case studies and related

researchVol. 3: Regional studies and volcanic facies

controls.Vol. 4: Field meeting guide, Mt Windsor Volcanic

Belt.

Acknowledgements

This project has been supported by the followingcompanies and organisations:

Aberfoyle Resources Limited

Copper Mines of Tasmania

Denehurst Limited

Mineral Resources Tasmania

Normandy Exploration

Pasminco ExplorationQueensland Metals Corporation Ltd

RGC ExplorationRio Tinto Exploration

On behalf of the research team I would like tothank all the company representatives, collaboratorsand AMIRA for their support and scientificinteraction throughout this three year program. In

par~cularwe are indebted to those companies thatprovided access to their deposits for the case studies:RGC, Pasminco, Murchison Zinc, Copper Mines ofTasmania and Aberfoyle.

This project would not have been possible withoutthe very significant contributions by a number of

dedicated and hardworking postgraduate students:Catherine Gifkins, Robina Sharpe, Mark Doyle,

Holger Paulick, Bill Wyman and Russell Fulton.Thanks also for the tireless work of Mike Blake in

organising the alteration data sheets, and to Nilar

Hlaing for printing and collating the papers. As usual

June Pongratz has done a great job in coordinatingand producing this final report.

We hope that the final outcome of this project is

the discovery of a new VHMS deposit in the nearfuture.

U~__"'4

Ross R. LargeDirectorCentre for Ore Deposit Research.

CODES: AMIRA/ARC Project P439­Studies of VHMS-related alteration: geochernical and

mineralogical vectors to ore. May 199800•CODES SRC