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

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Report 1Novambe r 1995

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

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AMIRAlARC project P439

Report 1November 1995

Centre for Ore Deposit and Exploration Studies ~University of Tasmania ~

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Contents

Structure and management of the project 1

Volcanic fades module: an outline of aims and objectives- Jocelyn McPhie and Rod Alien 5

Volcanic facies alteration in the Cambrian Tyndali Group, Mount Read Volcanics,western Tasmania - Matthew White 11

Subaqueous silicic volcanism in the Mount Black Volcanics, western Tasmania- Cathryn Gifkins 19

Regional geochemistry/petrology module 27

GIS report - Nathan Duhig 29

Evaluation of the role of Cambrian granites in the genesis of world-class VHMSdeposits in Tasmania - R. Large, M. Doyle, O. Raymond, D. Cooke,A. Jones, L. fIeasman 39

Cambrian granites in western Tasmania and their association to volcanic-hostedcopper-gold-bearing massive sulfide deposits 57

Geochemistry of the host volcanics to the Banambra massive sulfide deposits,Victoria, Australia, and the importance of silicic magmatism in VHMSmineralisation - A.J. Stolz, G. Davies and R. Alien ; 63

Geochemistry of the Mt Windsor Volcanics: implications for the tectonic setting ofCambro-Ordovician VHMS mineralisation in northeastern Australia- A.J. Stolz 93

Mineralisation and alteration module 117

Lithogeochemical exploration for metasomatic alteration zones using Pearce elementratios: Heliyer case study - eR. Stanley and J. B. Gemmeli 119

Heliyer hangingwall alteration study - R. Fulton and J.B. Gemmeli 123

Rosebery site study - R. Large 127

Textures and origins of carbonate associated with the volcanic-hosted massive sulfidedeposit at Rosebery, Tasmania - Anthea Hill and Karin Orth 129

Volcanic facies relationships and hydrothermal modification of primary volcanictextures at the Thalanga deposit - Anthea Hill 143

A comparison of volcanic fades architectire and alteration styles of felsic amdmafcvolcanic host sequences to massive sulfide deposits - Thalanga, northernQueensland and Teutonic Bore, Western Australia - Holger Paulick 147

Preliminary investigation of alteration at the Highway and Reward deposits,Mount Windsor Volcanics, Queensland - Mark Doyle 149

CODES: AMIRA Project P439 - Studies of VHMS-related alteration:~geochemical and mineralogical vectors to ore. November 1995~

1

Structure and Management of the Project

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Introduction

Volcanic-hosted massive sulphide deposits (VHMS)provide a significant contribution to the total zinc,copper, lead, silver and gold production in Australiaand continue to be a major target for most base metalexplorers. However, due to the geological complexityof andent submarine volcanic terrains, new VHMSdeposits are becoming extremely difficult to discover,especially deposits that are buried more than a fewtens of metres below the surface. To complement theconventional multidisdplinary approach utilisinggeology, geophysics and geochemistry, a new attackto the problem is proposed here which involves theintegration of volcanic fades analysis with alterationgeochemical and mineral chemical studies to developa set of vectors to guide explorers toward ore-grademineralisation. The research will concentrate on threeproductive submarine volcanic belts in Australia:the Mount Read Volcanics (MRV) in westernTasmania, the Mount Windsor Volcanics (MWV) innorthern Queensland, and the Archean Murchisonvolcanic province in western Australia.

Project objectives

1. To characterise the mineralogy and geochemistryfor the various styles of hydrothermal alterationthroughout the Mount Read Volcanics (MRV) andthe Mount Windsor Volcanics (MWV). This willbe based on mapping supported by whole-rockand trace element geochemistry, mineralchemistry, REE and stable isotope geochemistry.

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

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

4. To develop a set of vectors towards ore, based onthe· regional studies and ore deposit specificstudies, that can be applied in the exploration forVHMS deposits in submarine volcanic sequencesthroughout Australia. The vector matrix willinclude whole-rock, trace element, mineralchemistry, REE, isotope and volcanic facies factors.

Research framework

As there has been considerable research on alterationmineralogy and geochemistry ofVHMS systems, ourresearch is not to repeat previous work but to breaknew ground, utilising a multi-disciplinary approachat both the regional volcanic belt scale and selectedore deposit scale, with emphasis on selectivegeochemical techniques.

The project consists ofthree research modules asoutlined on page 2.

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CODES: AMIRA Project P439 - Studies of VHM5-related alteration:~geochemical and mineralogical vectors to ore. November 1995~

2

Volcanic Facies Module Regional Geochemist..ylPetrology Module

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Mineralisation andAlteration Module

Project Leader: Ross Large

Team Leader: Bruce Gemmell

Team Leader: Jocelyn MCPhie 8Team Leader: Joe Stolz

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Synthesis of alteration \~evolution and developments:

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This report

This is the first major progress report on the projectand covers the first six-month period from May toOctober 1995. Very good progress has been achievedin all three modules.

1. Volcanic Facies

• Jocelyn McPhie provides an overview of thestructure and objectives of the module.

• Matthew White reports on the volcanic fades andalteration in the Tyndall Group of the Mount ReadVolcanics (MRV).

• Cathym Gifkins provides a preliminary report onthe Mount Black Volcanics in the Rosebery area.

2. Regional geochemistry/petrology module

• Joe Stolz provides an overview of the structureand objectives of the module.

• Nathan Duhig discusses the geochemical databasefor the MRV and preliminary interpretations.

• Ross Large describes a recent model for theimportance of the Cambrian granites to mineral­isation in the MRV.

• Bill Wyman provides a preliminary report on thegranitoids and associated alteration in the Mt Lyell­Darwin area.

Structure and management of project 3

3. Mineralisation and alteration

• Bruce Gemmell provides an overview of thestructure and objectives of the module.

• Bruce Gemmell describes the Pearce-Element Ratiolithogeochemical research and hangingwallalteration study at the Hellyer deposit, Tasmania.

• Ross Large discusses the proposed Roseberycarbonate case study and potential research at theHenty deposit, Tasmania.

• Karin Orth and Anthea Hill describe their researchon the carbonate alteration at Rosebery.

• Anthea Hill and Holger Paulick report on progressto date on the volcanic fades and alteration at theThalanga deposit, Queensland.

• Mark Doyle provides an update on the volcanicfades and alteration research at the HighwayReward deposit, Queensland.

Important data and interpretations are alreadyemerging from this project which will haveimplications for exploration and will be discussed indetail at the November meeting. Progress in the firstsix months of the project has been very encouragingand I would like to acknowledge the excellent workby the CODES research team and the cooperationprovided by the sponsor companies.

Ross LargeDirector

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• Joe Stolz gives an update on the volcanicgeochemistry for the Mount Windsor Volcanics(MWV), QLD and the Benambra Volcanics, VIe.

CODES: AMIRA Project P439 - Studies of VHM5-related alteration:~geochemical and mineralogical vectors to ore. November 1995~