Porphyry Cu Au

An AMIRA collaborative research proposal between theCentre for Ore Deposit Research (University of Tasmania), CSIRO, and the

Centre for Strategic Mineral Deposits (University of W.A.)

Giant PorphyryCopper-Gold Deposits

A contribution to:Hydrothermal Systems,

Giant Ore Deposits&

A New Paradigm forPredictive Mineral Exploration

P511

JULY 1998

COMMERCIAL-IN-CONFIDENCE

The contents of this Proposal are confidential to Centre for Ore Deposit Research (Universityof Tasmania), CSIRO Exploration & Mining, Centre for Strategic Mineral Deposits

(University of Western Australia) and The Australian Minerals Industry Research Associationand are made available to possible participants in the Project solely for the purpose ofinviting their interest and are not to be used for any other purpose or disclosed or made

available to any other person or body.

Giant Porphyry Copper-Gold Deposits ProposalHydrothermal Systems, Giant Ore Deposits & a New Paradigm for Predictive Mineral Exploration

i

PreambleRELATIONSHIP OF CODES PROJECT TO AMIRA GODS RESEARCHPROGRAM P511This document is an outline of a collaborative research proposal between the Centre for Ore DepositResearch (CODES) , University of Tasmania and CSIRO on Giant Porphyry Cu-Au Deposits, to bemanaged by AMIRA.Giant Porphyry Cu-Au Deposits (CODES Project) will be a subproject of Hydrothermal Systems,Giant Ore Deposits & A New Paradigm for Predictive Mineral Exploration - P511 (the GODSResearch Program). GODS commenced in early 1998, and will continue until early 2001. Anycompany sponsoring the CODES project will automatically join P511, gaining full access to theresults of that project. Likewise, existing sponsors of the GODS AMIRA project P511 will gain fullaccess to the results of the CODES project. This complete exchange of information will be mutuallybeneficial, and will help lead to the overall success of both projects.In April 1998, a Strategic Partnership in Industry Research and Training (SPIRT) project proposalwas submitted to the Australian Research Council (ARC), seeking funds to match industry fundingthat we are seeking for the CODES proposal. If we fail to gain industry support, the application forARC matching funds will be withdrawn. Should this occur project P511 will continue in its currentform, without a major porphyry Cu-Au component.The following document outlines the aims and scope of the Giant Porphyry Cu-Au Deposits (CODESProject). It also discusses the broader scope of the GODS Research Program (P511), explaining howthe current proposal on giant porphyry copper-gold deposits will be integrated within GODS.A minimum of four companies is required to ensure that the Giant Porphyry Cu-Au Deposits projectwill attract SPIRT funding and thus proceed.

GODS RESEARCH PROGRAM P511 - EXECUTIVE SUMMARYThe QuestionWhere and how does nature create giant, high grade mineral deposits?

A holistic view of the ore systemPrevious attempts to address this question have sought empirical criteria for the giant ore deposits.The approach has not been successful. This research is taking a holistic view of ore systems andaims to elucidate the key processes within hydrothermal systems which determine the formation ofthe giant deposits, both at the regional and deposit scales. The research is combining traditionalempirical approaches, conceptual methods and numerical modelling. Some of the major themesbeing investigated include

the role of basement structures

nature of fluid reservoirs within the crust and the role of regional seals in preserving anddispersing reservoirs

reservoir evolution with depth, temperature and pressure

mixing of fluids of contrasting chemistry from different reservoirs and hypogene enrichment asmechanisms for generating high grades

Soft - hard model approach to developing mineral-systems concepts Available data from all scales - regional, deposit, microscale - is being integrated into softconceptual models of the hydrothermal systems which formed the outsized deposits.


ii

The soft models, together with 3-D geological models of the crust, provide a framework forevaluating quantitative 4-D (hard) models of the development of fluid reservoirs within the crust andof mechanisms of focusing fluids from major reservoirs into sites of ore formation. Key results from the modelling will be tested with selected acquisition of new data.

Work Program GODS Research Program The focus of the project is on the nature of fluid reservoirs within Au and Cu-Au systems, theinfluence of the architecture and geodynamic processes on fluid release from reservoirs, fluid flowpaths and the processes of metal transport, deposition and enrichment. The following three regions are being studied initially:

Papua New Guinea Irian Jaya

Northern Chile

Kalgoorlie

Work Program CODES ProjectThis SPIRT project will investigate the role of high level magma chambers as reservoirs forhydrothermal fluid and the interplay of magmatic and non-magmatic fluids around these chambers.This project utilises the expertise in porphyry deposits available through the Centre for Ore DepositResearch at the University of Tasmania. Systematic geochemical studies will seek to fingerprint theortho-magmatic stages of productive magma chambers (both hydrothermal and magmatic products)and differentiate the hydrothermal stages dominated by non-magmatic fluid reservoirs. Research willinclude sulfur isotope systematics, magnetite chemistry and distribution, vein and alterationmineralogy and geochemistry and fluid inclusions, focusing on the giant ore deposits in Chile andPapua New Guinea/Irian Jaya.

Structure and Funding The GODS Research Program is a collaborative venture between CSIRO, Centre for Strategic MineralDeposits (CSMD), University of Western Australia and CODES Special Research Centre, Universityof Tasmania and is based on three closely linked projects (see Figure below). A fourth project,funded by a ARC Large Grant at CSMD, will feed results into the AMIRA project although it is notan official part of GODS.

Hydrothermal Systems, Giant Ore Deposits &A New Paradigm for Predictive Mineral

Exploration P511

CSIRO

Fault Architecture

Large ARC Grant

CSMDUWA

AMIRA NON -AMIRA

Giant Porphyry Cu-AuDeposits

SPIRTCODES

Uni. Tasmania

The Conjunction ofPhysical and Chemical

Factors Responsible for theFormation of World Class

Orogenic Lode-Gold DepositsSPIRTCSMDUWA


iii

The GODS Research Program - P511

Hydrothermal Systems, Giant Ore Deposits & A New Paradigm for Predictive MineralExploration. Currently with ten sponsors.

SPIRT project at University of Western Australia The Conjunction of Physical and Chemical Factors Responsible for the Formation of World ClassOrogenic Lode-Gold Deposits.

SPIRT project at the Centre for Ore Deposit Research, University of TasmaniaGiant porphyry Cu-Au deposits. Submitted as a SPIRT proposal to the ARC in April, 1998

An additional four sponsors are required for the CODES project to ensure that the SPIRT applicationis successful.

Large ARC Grant funded project at CSMD, University of Western Australia. Fault architecture.This is not part of GODS but results from this project will flow through into GODS.

ReportingSince the three-year CODES project will commence one year after the GODS Research Program(P511) started it will not be completed until one year after the official completion of the GODSResearch Program, as a result we are proposing the following reporting strategy:

A penultimate report will be produced at the end of three years (early 2001) for the GODSResearch Pogram, encompassing the Lode _Au project and results of the CODES project up to thattime,

A final report will be produced for the CODES Project only at the end of the project. A fully integrated report for the GODS Research Program, encompassing all the results of the

Giant Porphyry Cu_Au project, will then be distributed to sponsors. We must emphasize that it is our intention to report project outcomes to sponsors on a continuous

basis. As part of this process, a support group will be established to disseminate information asresults come through.

PERSONNELGiant Ore Deposits Research Program - Project LeadersDr John L. Walshe Project Leader: GODS AMIRA Project P511

Specialist in geology and geochemistry of hydrothermal systems.Prof. David Groves - SPIRT (Lode Au)

Economic geologist, specialist in lode gold deposits.Director of the Centre for Strategic Mineral Deposits, Geology Department, University ofWestern Australia

Dr David Cooke SPIRT (Giant Porphyry Cu-Au)Specialist in hydrothermal geochemistry and magmatic-hydrothermal systems.

GODS Team Members, CSIRODr. Graham Carr North Ryde Pb isotope geochemistryMrs. Gem Midgley Nedlands Database and project managementDr. Alison Ord Nedlands Deformational modellingDr. Chris Ryan North Ryde PIXE analysis, fluid inclusion geochemistryDr. Phaedra Upton Nedlands Thermal and deformational modellingDr. Paul Gow Nedlands Thermal and deformational modellingDr. Chongbin Zhao Nedlands Thermal modellingDr. Hans Muhlhaus Nedlands Geomechanics


iv

SPIRT Lode Au Team Members, University of Western AustraliaDr. Neal McNaughton Pb isotope geochemistryDr. Steffen Hagemann Hydrothermal geochemistryDr. Carl Knox-Robinson Geographical information systemsDr. Derek Wyman Economic geology, metallogenyDr. Ed Mikucki Hydrothermal geochemistry

SPIRT Giant Cu-Au Team Members, University of TasmaniaDr David Cooke Porphyry Cu-Au & hydrothermal geochemistry


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TABLE OF CONTENTS

RELATIONSHIP OF CODES PROJECT TO AMIRA GODS RESEARCH PROGRAM P511. I

GODS RESEARCH PROGRAM P511 - EXECUTIVE SUMMARY.............................................. I

PERSONNEL...................................................................................................................................... III

GIANT PORPHYRY COPPER-GOLD DEPOSITS......................................................................... 1I. GOAL ......................................................................................................................................... 1II. SIGNIFICANCE......................................................................................................................... 1III. RESEARCH PLAN .................................................................................................................... 4IV. TIMETABLE.............................................................................................................................. 8V. BUDGET .................................................................................................................................... 9

HYDROTHERMAL SYSTEMS, GIANT ORE DEPOSITS & A NEW PARADIGM FORPREDICTIVE MINERAL EXPLORATION ................................................................................... 10

I. INTRODUCTION .................................................................................................................... 10II. THE WORK PROGRAM......................................................................................................... 11III. SOFT - HARD MODELLING STUDIES ................................................................................ 11

A) Papua New Guinea - Irian Jaya............................................................................................... 11B) Northern Chile Regional Study ................................................................................................ 14C) Kalgoorlie Regional Study ....................................................................................................... 15

IV. PROGRAM STRUCTURE AND FUNDING.......................................................................... 17V. DELIVERABLES..................................................................................................................... 19VI. TIMETABLE............................................................................................................................ 20VII. BUDGET (EXCLUDES THE CODES GIANT PORPHYRY CU-AU PROJECT)................ 21VIII. KEY PEOPLE FOR THE SOFT - HARD REGIONAL MODELLING.................................. 22

SPIRT LODE AU PROJECT............................................................................................................. 23I. GLOBAL- TO TERRANE- SCALE STUDIES....................................................................... 23II. DISTRICT-SCALE STUDIES ................................................................................................. 23III. DEPOSIT-SCALE STRUCTURAL, HYDROTHERMAL AND FLUID CHEMISTRY

CONTROLS ............................................................................................................................. 24

LARGE ARC FAULT ARCHITECTURE PROJECT.................................................................... 26

COLLABORATION BETWEEN CSIRO, CODES, CSMD AND INDUSTRY ........................... 27

REPORTING, TECHNOLOGY TRANSFER & CONFIDENTIALITY...................................... 27

INTELLECTUAL PROPERTY......................................................................................................... 28

REFERENCES .................................................................................................................................... 28


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GIANT PORPHYRY COPPER-GOLD DEPOSITSI. GOALThe SPIRT project on Giant Porphyry Cu-Au deposits will investigate the role of high level magmachambers as reservoirs for hydrothermal fluid and the interplay of magmatic and non-magmatic fluidsaround these chambers utilizing the porphyry copper and geochemical expertise available through theCentre for Ore Deposit research at the University of Tasmania. Systematic geochemical studies willseek to fingerprint the ortho-magmatic stages of productive magma chambers (both hydrothermal andmagmatic products) and differentiate the hydrothermal stages dominated by non-magmatic fluidreservoirs.The principal research topics will:1. Magnetite distribution, mineral and whole rock geochemistry2. Fluid inclusions and vein paragenesis

Specifically, we will analyse: Homogenisation temperatures and salinities conventional microthermometric techniques Cation ratios (Na/K, Na/Ca etc) analyse decrepitates using EMP +/- laser Raman Daughter mineral composition SEM and/or laser Raman spectroscopy Gas compositions (CO2, CH4, SO2 etc) laser Raman spectroscopy

3. Sulfur isotope systematics4. District-scale alterationThe research project will be lead by Dr. David Cooke (CODES) and Dr. John Walshe (CSIRO), andwill include a research team of one postdoctoral research fellow and two PhD students.The project will identify magmatic, lithological and hydrothermal controls on brine compositions, testhypotheses on the diversity of processes operating within the giant Cu-Au porphyry systems and helpidentify the key geological and geochemical elements of hydrothermal systems that generate giantporphyry deposits.The focus will be on the giant deposits in northern Chile and/or Papua New Guinea. The final outputwill be a set of geological and geochemical criteria to be used by mining companies for targetevaluation and exploration in Australia and overseas. This knowledge will make Australian porphyryexploration more efficient and competitive in both the local and global context.

II. SIGNIFICANCETowards an Understanding of Giant Porphyry Cu -Au SystemsPorphyry deposits are the world's principal copper resource, and are also an important source of gold,with many of the largest, recently discovered Au resources located in porphyry mineralising systemsin Pacific Rim countries (Cooke et al., 1998a). Australia has several typical porphyry Cu-Audeposits that are currently being mined or developed (eg. Cadia and Goonumbla). As the Australianmining industry strives for greater efficiency and profitability, there is a growing demand for largetonnage, high grade giant resources such as the Grasberg, Ok Tedi and Bingham Canyon porphyryCu-Au deposits of Irian Jaya, Papua New Guinea and the USA. Mirroring this demand is anincreased awareness that we lack an understanding of the processes required to form these premiumresources. The general processes of ore formation are understood, but not the particular processesthat lead to giant ore deposits. Without this understanding, we are unable to devise effectiveexploration criteria to maximize the chances for new discoveries.Clark (1993) has conceded that it is not possible to develop a set of descriptive criteria for outsizedmineral deposits. Determining the factors that govern the location, size and grade of mineral depositsrequires a judicious combination of the empirical and conceptual approaches to understanding ore-forming processes. The construction of the truly giant deposits requires effective methods of storinglarge volumes of fluids within the Earths crust, while sustaining metal and sulfur solubility within


2

these fluids. It is important to understand the processes operating at the regional to crustal scales thatgive rise to reservoirs of heat, salinity, acidity, sulfur and redox capacity within the crust and mantle.These are effectively the metal reservoirs, or are the reservoirs of the critical reagents (oxidant,reductant, etc.) required for metal transport/precipitation. Equally, it is important to understand themechanisms of fluid release from these reservoirs, and of the focusing mechanisms at the trap site thatoperate while maintaining chemical integrity of the fluids. Maintaining fluid pressure as well astemperature within fluid reservoirs is also likely to be of paramount importance. Commonly, thepartial pressure of the acid volatile species (CO2, H2S, SO2 and HCl) determines acidity, oxidationstate, sulfur concentrations and maintains a balance of both metal and the sulfur components withinthe fluid. Loss of fluid pressure is likely to lead to a degradation of the reservoir both in terms ofvolume of available fluid and its chemical potential for deposit formation. However, in a pre-existingzone of mineralization, a loss of fluid pressure can lead to sulfide dissolution and a significantupgrading of the resource. There is a need to recognise the existence and extent of any regional seals,be it a plug in the top of a magma chamber or a clay horizon within a sedimentary basin, and to learnto recognise when one or several reservoirs have released fluids in a controlled and focused way.These are likely to be times of great potential for the formation of large tonnage and high-gradehydrothermal deposits.

Brine & gas reservoir within

magma chamber

GroundwaterReservoir

RegionalSealChuquicamata

La Escondida

Radiomiro TomicZaldivar

1km 5km 200km

1

10

100 km

Recent advances in understanding the regional settings of porphyry Cu-Au deposits in PNG-IrianJaya, southwest United States, Lachlan Fold Belt and northern Chile suggest sub-volcanic magmachambers play an important role in the formation of porphyry deposits, acting as reservoirs of magma,saline brines and magmatic vapour. Other key elements of the architecture of porphyry and relatedhydrothermal systems appear to be large-scale structures (arc-parallel and arc-normal) and regionalseals within the host sequences. The key to the formation of the giant deposits appears to lie in acomplex interplay of fluids from magmatic and non-magmatic reservoirs, with focusing mechanismsgoverned by fault networks, and critical gas pressures determined by seals around and above magmachambers. High metal grades are possible when large gradients are generated and sustained in one ormore solution parameters (temperature, acidity of fluid, redox state of fluid, salinity of fluid andconcentration of volatile species, particularly sulfur). The mechanisms for sustaining these gradientsare limited. Common processes include reactions of fluids with specific host rocks, phase separationat particular sites and mixing of fluids (liquids and/or gases). Fluid-rock reactions and phase-separation mechanisms have limited capacity to maintain gradients and generate both large tonnageand high grades. Processes involving the mixing of large volumes of fluid with strongly contrastingproperties or processes involving the recycling and upgrading of initially low-grade deposits arepotentially the most effective mechanisms for generating both high grade and large tonnage deposits.

Figure 1


3

Ultimately, large tonnage, high-grade resources appear to have complex histories of formation. Fromthe work of Zentilli et al (1995) on the Chuquicamata deposit, it is possible to argue that giantdeposits may result from a two-stage process, as outlined in Figure 1: an initial proto-ore developsduring the ortho-magmatic stages of the system remobilisation and upgrading of this proto-ore bypara-magmatic fluids results in the formation of a large tonnage, high grade resource at a high level inthe system. This reworking may take place over considerable (km-scale) vertical distances within thecrust. If the giant deposits are products of complex processes involving reworking of previouslydeposited sulfides, then it will be necessary to clearly identify each stage in the rock record.Questions that must be posed include: Is it possible to determine if and when a sub-volcanic chamber acted as a reservoir for metal-rich

brines or vapour from the geochemistry of its high-level magmatic products? Is it possible to recognize regional architectures that facilitate reworking processes? Is it possible to resolve the relative roles of magmatic and non-magmatic fluids in the

remobilization stage?

Figure 2

Vapour-phase Fingerprints

tourmal ine

anhydr ite (SO2)

hemati te

molybdenite(high HCl/H2O)

-ve sulfur isotopes (SO2)

Potassic a lteration

Sodic a lterat ion/magnet ite

Regional Seal

Zone of secondary enrichment

5 km

2 km

vapour

brine


4

III. RESEARCH PLANTo test the hypotheses outlined above, field investigations and detailed geochemical investigationswill be combined. An integrated approach will be adopted, with each team member contributing to anoverall synthesis of the results and development of exploration parameters. The postdoctoral researchfellow (to be appointed) and chief investigator (Cooke) will conduct the more regional aspects of thefield studies, with deposit-specific studies undertaken by the two PhD students.Researchers in this project will have full access to analytical equipment at CODES, the GeologyDepartment and the Central Science Laboratory at the University of Tasmania. This includesfacilities for the preparation of thin sections and polished sections, petrologic microscopes, a widerange of computers, drafting equipment and a scientific library. Equipment available for the researchproject includes an automated XRF unit, fluid inclusion and melt inclusion facilities, stable isotopeanalytical equipment (conventional & laser ablation), scanning electron microscope, an electronmicroprobe and a new laser ablation ICP-MS facility. Laser Raman analyses will be conducted atAGSO, oxygen isotope analyses at Monash University and radiogenic isotopes at the University ofAdelaide.

The major research themes will be as follows:1) Magnetite Distribution, Mineral and Whole Rock Geochemistry: It may argued that the ortho-magmatic stages of porphyry deposits are the products of fairly standard magma chambers thatessentially behave as sealed reservoirs of hydrothermal fluids (brine and vapor). A critical issue islearning to recognize if and when magma chambers behaved in this productive fashion. If highlysaline brines are capable of transporting high field strength elements and if such brines coexist withsmall volumes of melt at a late stage, it may be possible for the brine to buffer the concentrations ofhigh field strength trace elements in the melt. Concentrations of these elements in late dykes would bean indicator of a productive reservoir at depth. There is a need for an integrated geochemical study ofthe late magmatic products and the early alteration products in productive systems to evaluate thispossibility. Consequently, we plan to investigate the distribution of magnetite (both magmatic andhydrothermal) within giant porphyry deposits and in the surrounding regions (eg. the core of theGrasberg deposit contains > 7% magnetite, which is coincident with the highest gold grades of > 4g/t). Magnetic susceptibility measurements are an initial guide to magnetite content of lithologies andalteration assemblages, and will be used to help systematically sample the various types of magnetite.Petrographic and geochemical analyses (electron microprobe - EMP, scanning electron microscopy -SEM and oxygen isotopes) will then be used to characterise the different varieties of magnetite, tracefluid sources responsible for hydrothermal magnetite deposition, determine the temperatures offormation (by analysing 18O in magnetite-quartz pairs) and to determine the importance of magmaticmagnetite in both the formation and fingerprinting of giant porphyry Cu-Au deposits. For themagnetite-bearing intrusions and related lavas, samples will be analysed major, trace and REEcompositions and radiogenic isotopes (Nd, Sr, Pb) to help identify magma sources, petrogeneticrelationships and to try and identify the relative importance of mantle and crustal processes in theformation of giant porphyry Cu-Au deposits.2) Fluid Inclusions and Vein Paragenesis: Detailed studies of fluid inclusions, placed in aparagenetic (temporal) context, are essential for determining the role of brine chemistry in forminggiant porphyry deposits, and to test hypotheses about depositional processes (fluid mixing, phaseseparation, etc.). There seems to be a first-order distinction between porphyry deposits which areproducts of fluids exsolved from a magma chamber (ortho-magmatic fluids) and those which areproducts of evolved magmatic fluids (para-magmatic fluids), substantially modified by fluid-rockreactions and/or mixing with non-magmatic fluids. In the latter case, metals may be largely derivedfrom the intrusive complex, but the metal contents of the fluids reflect their extensive subsolidushistory. The salient characteristics of deposits in which ortho-magmatic processes played asignificant role are early high temperature Fe-Na Ca metasomatism, characterized by plagioclase biotite and magnetite (M veins of Clark, 1993) with highly saline (> 50-90 wt. %) fluid inclusions (eg.Endeavour 26N, NSW; Park Premier, Utah; El Salvador, Chile; Panguna, Papua New Guinea).


5

Commonly, the most saline fluids are also the most sodic (Figure 3). The porphyry deposits mostlikely to have formed by para-magmatic processes are those in which the deposition of sulfides isrelatively late in the paragenesis (eg. Ann-Mason, Yerrington Batholith; Nevada; Bingham, Utah;Santa Rita, New Mexico; Sierrita, Arizona). In these deposits, the early M and A veins are missingand deposit formation begins with the formation of a sulfide-poor quartz stockwork (most probablyequivalent to B veins, using the vein terminology of Gustafson and Hunt, 1975) and associatedpotassic alteration (K-feldspar - biotite). Deposits such as Bingham, which do not display the earlystages of this paragenesis, lack the highly saline and sodic fluid inclusions. Detailed analyses of fluidinclusions in the mineralised vein stages of giant porphyry Cu-Au deposits will therefore beundertaken to help understand the origins and compositions of brines and gases that form giantporphyry Cu-Au deposits, and to evaluate if there are any unique characteristics. Specifically, we willanalyse:

Homogenisation temperatures and salinities - conventional microthermometric techniques

Cation ratios (Na/K, Na/Ca, etc.) analyse decrepitates using EMP +/- laser Raman Daughter mineral compositions SEM and/or laser Raman spectroscopy

Gas compositions (CO2, CH4, SO2, etc.) laser Raman spectroscopy

Figure 3

H2O

NaCl KCl

Bingham

Ear ly barren quar tz ve inswith molybdenite pyr i te

B-vein equivalents

Para-magmat icFluids

Park PremierA/B - vein stagequartz K-feldspar magnet ite pyr ite chalcopyrite

Park PremierM-vein stagemagnet ite + act inolite Na-p lagioc lase quartzbiot ite & pyroxene stab le

Ortho-magmaticFluids

Park P remie rType C

B ingham

Park P remierType D

quar tz poorsulf ide r ich

C&Dvein fluids


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3) Sulfur Isotope Systematics: Sulfur isotopes provide information about the sulfur source and/or theredox state of the system. The strongly negative numbers for sulfide seen in some deposits (eg. ElSalvador; early stage, & Goonumbla; Figure 4) are taken to reflect very oxidized fluids of ortho-magmatic origin with bulk fluid compositions around 0. However, most data sets are morepositive. The positive shift in the late stage at El Salvador was interpreted in terms of ingress ofgroundwater into the system. If this is a common process, then the sulfur budgets of the productivestages of a host of deposits - Bingham, Grasberg, El Teniente, Rio Blanco may have been dominatedby country rock sulfur. However, it is not clear how variable the magmatic sulfur signature might be.To resolve this issue there is a need to determine the sulfur isotopic compositions of sulfides inmagmatic sulfides in coeval volcanics and also to determine the bulk sulfur isotopic compositions ofcountry rocks. Sulfur isotope analyses will also be used to trace fluid and sulfur sources, and todetermine if any isotopic zonation exists around giant porphyry Cu-Au deposits. The laser ablationsystem for analysing sulfur isotopes at the University of Tasmania can analyses individual sulfidegrains with diameters as small as 100m. Previous sulfur isotope studies of porphyry deposits havebeen hampered by the requirement of coarse-grained sulfides for hand drilling. The laser ablationtechnique is ideally suited to a study of porphyry-style mineralization, because it can effectivelyanalyse the fine, disseminated sulfides that occur in the primary igneous lithologies, and in the variousalteration assemblages related to a giant porphyry system. In addition, under the auspices of an ARClarge grant at the University of Tasmania, Dr. Garry Davidson has been developing a whole rocktechnique for the analysis of sulfur isotopes in rocks that have low sulfur contents (eg. fresh dioritesand monzonites). We can use this technique to determine the primary magmatic sulfur isotopecomposition of the magmas responsible for giant porphyry formation. In addition to the importantscientific insights to be gained from this aspect of the project, our sulfur isotope research hasexcellent potential as an exploration tool within deposits and in mineralized districts, because it willbe able to detect any subtle sulfur isotopic zonation that may be associated with oxidation or otherprocesses that occur within giant porphyry deposits.4) District-Scale Alteration: To test how important fluid mixing is for the origin of giant porphyrydeposits, it is essential to investigate fluid compositions in the districts that host the deposits. Bystudying regional alteration assemblages (using alteration petrography, whole rock geochemistry,fluid inclusions and stable isotopes), it is possible to determine whether a given assemblage acted as ametal source or sink, whether the pore fluids were oxidized or reduced (eg. Cooke et al., 1998b), and,given suitable sample material and sample distribution, regional temperature gradients and directionsof fluid flow. If, as hypothesised, regional seals are important, then meteoric/connate waterconvection should have established distinctive background alteration assemblages such as the sodic-calcic assemblage at Yerrington, Nevada (Dilles and Einaudi, 1992), which is recognised to be aprograde assemblage formed by influx of pore waters from the country rocks into the intrusionsduring porphyry formation. These subtle regional alteration assemblages (eg. epidote-albite-pyrite-chlorite etc.) are the most common varieties encountered during exploration. A greater understandingof their importance and an evaluation of their potential as exploration vectors are of great relevance tothe mining industry.


7

Bulk sulfur isotopiccomposition

2 4 6 8 10 12 14 16 18 20 22 24

34SAnhydrite (0/00)

Rock

dom

ina

ted

??

Magmatic fluid dominated

XH2S >> XSO4

0.8

XH

2 S

= 0

.5

Porgera - stage 1(A veins)

XH2S ~ XSO4Porgera - stage 2

(D veins)

800 o C

600 o C

400 o C

300 o C

150 o C

0.63

4 S (0

/00)

- Su

lfide

Grasberg -paired sample

Ertsberg - paired sample

Goonumbla (E26N)

Bingham

Open symbols; sulf ide data only; temperature based on f luid inclusions

El Teniente, Rio Blanco

Gaspe

El Salvador

0

-4

-8

-12

-16

-20

+4

+8

+12

Figure 4


8

IV. TIMETABLEThe field component will be completed in two stages during the first 18 months. Petrographic andgeochemical analyses will continue from year 1 through to year 3, with a greater emphasis ongeochemistry in the later stages of the project. An additional half-year has been added allowing forcompletion of the APA-I (PhD) projects and integration of their results with the regional studies. Ifthe APA-I projects are completed within 3 years, then the additional 0.5 years will not be required:

Porphyry Cu-Au Module

99 00 01Mar Jun Sep Dec Mar Jun Sep Dec Mar Jun Sep Dec

Northern Chile

Field Program

Petrography

Geochemistry

Geochemical Modelling

Reporting

PNG-Irian Jaya

Field Program

Petrography

Geochemistry

Geochemical Modelling

Reporting


9

V. BUDGET1998 1999 2000 2001

Predicted IncomeAMIRA 42K 83K 83K 42KARC (SPIRT) 86K 87K 88K

Total 42K 169K 170K 130K

Expenditure - salaryStructural Post-doc 18K 57K 58K 41K2 PhD scholarships 40K 40K 40KPart time Research Assistant 9K 18K 18K 9K

Other ExpenditureGeochemical analyses 2K 13K 16K 24KFieldwork and assoc expenses PhDs 5K 6K

10K6K10K 3K

Travel 3K 15K 12K 8KAMIRA Fees 5K 10K 10K 5KTotal Expenditure 42K 169K 170K 130K


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HYDROTHERMAL SYSTEMS, GIANT ORE DEPOSITS & A NEWPARADIGM FOR PREDICTIVE MINERAL EXPLORATION

I. INTRODUCTIONThe ultimate goal of this project (including the CODES project), is to understand the factors thatgovern the location, size and grade of mineral deposits.There is increasing consciousness within the community that we lack an understanding of theprocesses required to form large tonnage, high grade deposits. The general processes of oreformation are understood but not the particular processes that lead to giant ore deposits. There is alsoawareness that regional-scale data, particularly geophysical data, are fundamentally modifyingperceptions of the physical dimensions of hydrothermal systems. It is increasingly possible to thinkin terms of ore-forming systems rather than ore deposits.Hydrothermal systems research necessitates a shift in perspective from the traditional deposit-oriented and class-oriented approaches to ore deposit research. There is a need for new skills andtools to permit development of holistic pictures of hydrothermal systems. There is a need for newskills to read from the rock record information about scale of systems, nature and location ofproductive fluid reservoirs, locations of major flow paths, and regional and local seals. There is alsoa need to understand what features of a deposit - even features at the microscale - are of significanceat the regional scale. Alteration assemblages, zonations and parageneses at the deposit scale havebeen traditionally interpreted in terms of fluid-rock reactions at that scale. From a hydrothermalsystems perspective many of these same features may be interpreted in terms of mixing of fluidsfrom different reservoirs. Such interpretations, if sustained, will be one of the ways of making thelinks between sites of ore formation, the regional-scale flow paths and fluid reservoirs. Fluid-rockreactions may play a far more significant role in the reservoirs and along the flow paths than at thesite of ore formation. A microscale texture, such as the replacement of sulfides by silicates or quartz,may have regional significance in much the same way as cleavage in a rock or thin-section may be ofregional significance. The rationale for this is that the texture reflects pressure perturbations in thesystem and such perturbations may be of regional significance.It is not possible to develop a set of descriptive criteria for outsized mineral deposits. Understandingwhy and where giant ore deposits occur will require a judicious combination of the empirical andconceptual approaches to understanding ore-forming processes. There is a need to critically re-examine the geological and geochemical data at all scales (regional, mine, micro) to provide a basisfor developing thoroughly integrated qualitative to semi-quantitative (soft) models of ore formation.The soft models, together with 3-D geological models of the crust, may provide a framework forevaluating quantitative 4-D models of the development of fluid reservoirs within the crust and ofmechanisms of focusing fluids from major reservoirs into sites of ore formation. The quantitativemodelling (the hard modelling) involves complete coupling between fluid flow, heat transport, rockdeformation and chemical reaction. It provides a holistic, quantitative view of the giant ore systems.The hard modelling is a tool to answer the what-if questions. It is potentially a new tool indesigning and evaluating exploration programs: the essence of the new paradigm in predictivemineral exploration.Relating processes to size and grade Mixing fluids of contrasting chemistry and hypogene enrichment, the reworking of pre-existingsulfidic domains in the rock column, are two important processes for attaining high grades. Largetonnage, high grade resources appear to reflect complex histories involving several differentprocesses that operated over time. Highly efficient focusing mechanisms are important: largedeposits are commonly related to large, deep-seated and long-lived fault systems. Many of thesethemes are common to various classes of hydrothermal deposits (porphyry Cu-Au, lode Au, MVT,syn-metamorphic and VMS deposits). It seems that it is possible to think in terms of a general theoryof hydrothermal systems and that it will be possible to make some quite powerful statements aboutwhy deposits are large, why they are high grade and where they might be found.


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Two themes woven into the fabric of this research may well be germane to genuine progress inunderstanding the origins of the giant deposits.These are:- the need to recognize the diversity and complexity of the processes- the need to integrate all of the data from the microscale to the crustal scale

II. THE WORK PROGRAMThe work program develops the soft model hard model concept.The modelling begins by asking the following five questions about the system.1. What is the system?2. What is the P-T and geodynamic history?3. What is the nature of fluid reservoirs in the system?4. What mechanisms advect/convect/focus fluids?5. What are the metal transport/depositional mechanisms of ore formation?The answers to these five questions generate the soft models that in turn provide a framework for thehard models. Quantitative modelling of hydrothermal systems places severe constraints on what ispossible. It is this holistic, quantitative view of the ore system that holds the key to the new paradigmin mineral exploration: utilizing modelling as a tool in designing and evaluating exploration programsat local, regional and crustal scales.The focus of the project is on the nature of fluid reservoirs within Au and Cu-Au systems, theinfluence of the architecture and geodynamic processes on fluid release from reservoirs, fluid flowpaths and the processes of metal transport, deposition and enrichment. The project is utilizing thenumerical modelling skills within the AGCRC and architectures largely derived from other studies bythe AGCRC, AGSO, state geological surveys and the exploration industry.The following three regions are being studied initially: Papua New Guinea Irian Jaya Northern Chile Kalgoorlie

The present status of the soft models and the concepts to be examined by the hard modelling withineach of these regions is summarized in this document. Assessment of all the data, from the deposit-scale to the regional-scale to the crustal-scale is beingutilized in developing soft and hard models of the ore forming processes. It should lead to therecognition of linkages between deposits, districts and provinces not previously appreciated.

III. SOFT - HARD MODELLING STUDIESA) Papua New Guinea - Irian JayaAim:To test some key concepts about fluid reservoir development within a system. These include: robustness of reservoirs - effectiveness of seals/development mechanisms mechanisms to trigger release of fluids role of regional uplift in developing reservoirs and providing triggers for focused release of fluids

from reservoirs how much fluid can be stored how effectively can it be delivered to site of ore deposition - time/velocity


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Region/deposit classes PNG/Irian Northern Kalgoorlie Carlin Wiluna

Jaya Cu-Au Chile Cu Region Au Au Au Priority

4 4 4 What is the system? Size ?? ?? ?? ?? ?? Structural architecture

Lithological architecture

Physical/chemical properties of rocks

Nature of fluids/reservoirs? Meteoric

Basinal brines Basinal devolatilization (hydrocarbons)

Lower-crustal devolatilization

Magmatic

Mantle

Mechanisms driving the fluids? Compaction Topography

Thermal - igneous complexes

Tectono-thermal-deformational

P-T / geodynamic history? Sedimentation/erosion

Extension

Thrust loading

Thermal time constants

Transport/depositional processes? Fluid mixing

Fluid/rock reaction

Phase changes/pressure seals

Hypogene enrichment

common parameters system specific parameters

The working hypothesis with respect to the Porgera deposit: Regional architecture Size of system

The working hypothesis for the Papua New Guinea - Irian Jaya region is that the deposits fromPorgera through Ok Tedi and Frieda River to Grasberg/Etrsberg may be considered part of onelarge system.

Structure There appears to be three important structural elements and we are focusing on these initially: Arc-parallel structures that align with the edge of the Australian craton. Arc-normal structures that appear to be reactivated basement structures in the Australian craton. A regional seal which is the thrust contact between the Darai Limestone and the Chim

Formation.

Lithologies Chim and Om Formations and black shale sequences Darai Limestone and correlates

Intrusive rocks Porgera Intrusive Complex - alkaline intrusive complex Other Late Miocene - Quaternary porphyries


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Figure 5

Figure 6

Darai Limestone

Porgera Complex - s ite of mixing ofoxidized and reduced f luids

Regional SealsConvection in this cel lgenerates homogenousA-vein f luid- reduced fluid- mixed igneous/sed isotopic signature

Intrusions -source of oxidized f luid

Section along the Porgera transfer(after H ill)

SSW NNE

Chim FormationOm Formation

Om Uplif t

??

1450 1500 155014001350

00

50

100Jurassic shales - Om Format ion

Upper Cretaceous clast ics - Chim Formation

Tert iary l imestone - Darai Limestone

Intrusions

Grasberg

Fr ieda

Ok Te di Porgera

Mt Kare

Nena


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Geodynamic History What is the relationship between uplift in the Papua New Guinea Irian Jaya region, magmatism andthe formation of mineral deposits? Part of the answer may lie in the need to load the system to activate the seals and form the reservoirs.Uplift may also provide triggers for focused release of fluids from reservoirs. Nature and location of fluid reservoirs that generated the Porgera deposit Reduced fluids: Stage 1 mineralization in the Porgera Au deposit is associated with reduced sulfideassemblages sitting in and around an alkaline intrusive complex. The Pb isotope data indicate that thePb in the fluids was mostly derived from igneous rocks and the Om Formation. This suggests thereduced ore fluid is a product of fluid interaction with sedimentary and igneous rocks which occurredat least three kilometres beneath the The hydrothermal history of the Porgera deposit suggests oxidized fluids were active in the system ata very early stage and also at a late stage during the formation of the high grade ore in the RoamaneFault. Some part(s) of the Porgera Complex is assumed to have formed the reservoir for the oxidizedfluid. Mechanisms of transport and deposition at Porgera Gold was deposited in Stage I from reduced fluids that had equilibrated with the black shales in the

stratigraphic column

Magmatic volatiles oxidised the reduced ore fluid during stage II

The strong redox gradients between the reduced and oxidized fluids generated the high gradeswithin the Roamane Fault

Significant remobilization of gold in the rock column occurred during stage IIMechanisms driving fluid flow and fluid focussing in the systemThe model of fluid reservoirs summarized in Figure 5. brings together the major elements of thegeology and geochemistry of the Porgera deposit. From modelling of the magnetic data, the top of thelarger body of intrusive rock at Porgera is taken to be 2-3 km below the present surface. Convectionled to a reduced fluid with a homogeneous isotope signature. It is suggested that the Darai Limestone- Chim Formation contact (a thrust fault) acted as a regional seal on the system. This seal would havecontrolled fluid pressures in the underlying rock column and breaking of the seal focused fluids intothe zone of mineralization.

B) Northern Chile Regional StudyAim:To test some key concepts about crustal magma chambers acting as fluid reservoirs in a linked-faultsystem and the interplay of magmatic and non-magmatic reservoirs: Determine the shapes of the deep magma reservoirs from geophysical data Modelling of fracture propagation around the model chamber with/without mineral precipitation

examining the influence of pre-existing structure and regional seals Examine the interplay between pre-existing structure and the chamber to locate the valves that

release fluids to a higher level in the between Model the role of gas pressure in driving hypogene enrichment processes in the system

The working hypothesis for the Northern Chile porphyry Cu deposits: Architecture of the system Size

Taken to be approximately the length of the west fissure.


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Structure Arc-parallel structures, dominated by west fissure but also E-W, NE and SW trending structures -these seem to be basement structures.

Lithologies Need to document the following elements: marine sediments - potential hosts of reduced-fluid reservoirs terrestrial sediments - potential hosts for oxidized fluid reservoirs potential regional seals relationships of volcanic rocks/dykes to chambers defined by magnetics

Geodynamic HistoryThe giant porphyry Cu deposits form within a relatively restricted time interval. What is the causalrelationship between subduction and ore formation during this interval?Nature and location of fluid reservoirs in the systemThe deep-seated magma chambers may act as reservoirs for ortho-magmatic fluid (brines and/orvapor) and non-magmatic fluid or evolved magmatic fluid reservoirs may occur external to the magmachambers.Available data on mineralogy, paragenetic relations, and isotopic compositions will be used to assessthe relative roles of ortho-magmatic and non-magmatic fluid reservoirs. Deposits to be studiedinclude El Teniente, Rio Blanco-Los Bronces, El Salvador, and Chuquicamata.Transport and deposition processesAvailable data will used to assess the role of gas pressure within the system in controlling availableacid and the mobility of Cu at both the ortho-magmatic and para-magmatic stages of the system.Numerical models will be developed to assess the role of gas pressure in hypogene enrichmentprocesses

C) Kalgoorlie Regional StudyAims:

To explore the interplay between structure and chemistry of fluid reservoirs in determininglocation, size and grade of deposits within the Kalgoorlie region

To understand the outstanding size and grade of the Golden MileChemistry modelling The numerical modelling of the chemistry will examine: The influence of the Golden Mile Dolerite on mineral assemblage and capacity to buffer the redox

state of the fluid The grade of gold that may be generated by reaction of fluid of variable pH and redox conditions

with the Golden Mile Dolerite The robustness of redox states set at deeper levels in the system. Will these conditions be

transferred to higher levels in the system or will they be reset by fluid-rock reaction along the flowpaths?

The effectiveness of mixing fluids of contrasting redox state to generate large tonnage/high graderesources

Soft Modelling The soft modelling will proceed by developing a GIS database of key geological, geophysical andgeochemical elements that will aid the correlation of fluid reservoirs and flow paths of contrasting


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chemistry with structure. Interest is particularly centred on resolving differences between sets of N-Strending structures and cross-structures. The elements of the database will include:

regional geology regional structures geophysical data sets major and minor deposits alteration styles presence of pyrite, pyrrhotite, hematite, magnetite, sulfate talc-carbonate alteration presence of minor phases (roscoelite, scheelite, Ni-arsenides, molybdenite, tourmaline) fluid inclusion data temperature and salinity variation in sulfur and carbon isotopes Pb isotope data age constraints on intrusions/alteration/mineralization

Working hypothesis for the formation of the Golden Mile deposits: Regional Architecture Size of the system

Crustal scale system. The Y-front seismic section provides one possible interpretation of the thirddimension of the system

Structures N-S trending

Early set with carbonate alteration that does not cut greenstone/basement contact N-E trending features in topography with some possible correlation with dykes - from

magnetic image. Locally late N-E structures control distribution of gold grades within N-Strending structures

Lithologies Do the Black Flag Beds act as a regional seal within the system?

What is nature of fluids / fluid reservoirs in the system? Fluid histories in the Golden Mile provide some insight into possible fluid reservoirs in the region. Atminimum, the mineralogy/geochemistry of the Golden Mile suggests two fluids

a reduced CO2-H2S-Au rich fluid an oxidized fluid - most likely magmatic

Correlation of Golden Mile and Kanowna Belle on same N-E suggests an oxidized fluid reservoir wastapped by at least one N-E trending structure. Arguably, the N-S trending structures carried the moretypical reduced, CO2 and gold-bearing fluid. Depositional Processes within the Golden Mile The outstanding size and grade of the Golden Mile mineralization may reflect a combination ofprocesses including:

effective focussing mechanisms extensive reworking and upgrading of the gold mineralization highly efficient deposition of the gold by oxidation of reduced gold-rich fluids


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In part, the Golden Mile Dolerite may have behaved as an aquiclude at the local to regional scalemaintaining the chemical integrity of reduced and oxidized fluids up to the point of mixing.

IV. PROGRAM STRUCTURE AND FUNDING A novel approach and a well balanced team The systems approach to the study of hydrothermal mineral deposits is novel and demands newapproaches to project structures, mechanisms of funding, collaboration between researchers andexploration geoscientists.

The project is constructed around the following constraints: A need to ask a diverse range of questions about mineral systems. Questions about architecture,

geodynamic history, fluid reservoirs, and mechanisms of fluid flow, metal transport anddepositional processes.

A need undertake research at different scales - terrane, district, deposit, microscale.

A need to spend time integrating data to develop robust soft models to focus the hardmodelling.

A need to utilize the knowledge and skills of university and CSIRO researchers and explorationgeoscientists.

A need to maximise the funding of the research by integrating AMIRA projects and SPIRT grants. The funding for the research is being arranged through three closing linked projects. The GODS Research Program - AMIRA project P511

Hydrothermal Systems, Giant Ore Deposits & A New Paradigm for Predictive MineralExploration The GODS project is currently funded by 10 sponsors.

SPIRT project at CSMD, University of Western Australia The Conjunction of Physical and Chemical Factors Responsible for the Formation of World ClassOrogenic Lode-Gold Deposits

SPIRT project at the Centre for Ore Deposit Research, University of Tasmania Giant porphyry Cu-Au deposits SPIRT Proposal submitted to ARC in April, 1998.

Large ARC funded project at CSMD, University of Western Australia. Fault Architectures. Notofficially part of the GODS research program but will feed results into the program

Collaboration between researchers and exploration geoscientists is being developed through a seriesof support groups.

The GODS project is unique in its character and scope. The GODS project is bringing together abreadth and depth of talent from the CSIRO, the Centre for Strategic Mineral Deposits at theUniversity of Western Australia, Centre for Ore Deposit Research at the University of Tasmania, theAGCRC and collaborative partners. The team encompasses skills in hydrothermal ore deposits,hydrothermal geochemistry, igneous petrology, basin analysis, isotope geochemistry, analyticalgeochemistry, structure, numerical modelling of fluid flow (thermal and deformational), geographicalinformation systems and exploration geoscience. The team blends the experience of internationallyrecognised geoscientists and experienced explorers with the youthful and talented enthusiasm of anew generation of geoscientists.


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District

Global

ResearchScales

TheQuestions

Integration&

Prediction

HagemannGrovesMikuckiSPIRT Au Rfellow & PhDsCookeSPIRT Cu-Au Rfellow & PhDsWalshe & Midgley

WalsheGowMcNaughton(Ord)CookeSPIRT Cu-AuRf ll & PhD

SPIRTAu/GODSSPIRTRfellow

Orogenic GoldDeposits

SPIRT Au SPIRT

Scale of system Porphyry Cu-AuDeposits

Global to Terrane

DepositScale

Provinceand

District

P/T historymagmatismgeodynamic

s

space/time

Transportand

Deposition

Architecture Reservoirs

LARGE ARCFaults-AuHagemannGrovesARC RfellowMcNaughton

SPIRTAuWymanGardollGroves(Barley)

GODSWalsheGow(McInnes)(Hobbs)(Ord)

GIS IntegrationGardoll

Knox-Robinson(Fractal Graphics)

Soft ModelsCSIRO Modelling Group

CSMD and CODES

GODS/SPIRT Au & Cu-Au

Global to DistrictExploration Criteria

Hard ModelsOrd and

CSIRO Modelling GroupGODS

PNG-Irian JayaNorthern Chile

Kalgoorlie RegionWiluna Region

Post-Rodinian Au, Cu-Audistribution

AMIRASponsors

GODS

SPIRT Au GODS SPIRT Cu-


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V. DELIVERABLES The deliverables of the GODS Research Program will be a series of atlases.

Deposit Elements Atlas Ore forming events; conditions of ore forming events; sources of hydrothermal fluids; characterand age of host-rock events; relative and absolute timing of host-rock and ore forming events.

Regional Elements Atlas Structural architecture; basin history; magmatic history of the region; metamorphic anddeformation history and nature of fluid reservoirs.

Atlas of Ore Deposit Models Soft and hard models of the hydrothermal system and ore-forming processes based onintegration of regional and deposit scale data, testing possible flow regimes, sites of reservoirdevelopment, flow paths and sites of ore formation.

Benefits: The systems approach to the study of the giant hydrothermal mineral deposits, the integration ofdeposit and regional scale data and the interplay of the soft and hard modelling has the potential toradically modify concepts of ore formation and significantly impact on exploration strategies. Thebenefits from this approach include:

Systematic compilation of the characteristics and settings of some of the truly giant metalresources.

New insights into links between characteristics and events at the regional scale with events andcharacteristics at the deposit scale.

New insights into links between different groups and classes of deposits providing increasedopportunity for lateral thinking and novel approaches to exploration.

New skills and tools to aid regional scale interpretation of hydrothermal systems.

Enhanced ability to evaluate the prospectivity of regions. Enhanced interaction between exploration geoscientists and research scientists.


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VI. TIMETABLE

REGIONAL STUDIES

98 99 00Mar Jun Sep Dec Mar Jun Sep Dec Mar Jun Sep

PNG-Irian Jaya

Architecture/geodynamic history

Fluids/reservoirs/transport/depositional processesPorgera Ok Tedi

Hard modellingReservoirs triggers

Kalgoorlie Region - Wiluna Region

Architecture/geodynamic history

Fluids/reservoirs/transport/depositional processes

Hard modellingradiogenic tracers

Northern Chile

Architecture/geodynamic historymagma chambers magnetics

Fluids/reservoirs/transport/depositional processes

Hard modellingfault architecture - f luid flow


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VII. BUDGET (EXCLUDES THE CODES GIANT PORPHYRY CU-AU PROJECT)

1998 1999 2000IncomeAMIRA 200K 200K 200KSPIRT 130K 120K 120KCSIRO 93K 93K 93K

Total 423K 413K 413K

Expenditure - salaryJLW (65%) 72K 72K 72KResearch assistant - Gem Midgley 46K 48K 50KStructural Post-doc 59K 59K 59KContr. hard modelling (Gow/Upton) 40K 40K 40K2 PhD scholarships 40K 40K 40KAdvertising/moving 10KPart-time assistance 20K 20K 20K

Other ExpenditureComputer/software 10K 10K 10KGIS 20K 20K 20KGeochemical analyses 26K 24K 22KFieldwork and assoc expenses PhDs 20K 20K 20KTravel 32.6K 32.7K 32.7KAMIRA Fees 27.4K 27.3K 27.3KTotal Expenditure 423K 413K 413K


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VIII. KEY PEOPLE FOR THE SOFT - HARD REGIONAL MODELLING

Region PNG-Ijaya Nth Chile Kalgoorlie WilunaSoft Modelling

Architecture / Geodynamics- P&T/Driving mechanismsStructures Gow Archibald

JLWDIG/SPIRT

RfellowLithologies Gow Archibald

JLWDIG/SPIRT

RfellowIntrusions/coeval volcanics Gow Archibald

JLWDIG/SPIRT

RfellowMagnetics assess plutons / structure Gow Archibald

JLWDIG/SPIRT

RfellowUplift data GowGeochemistry of igneous rocks McInnes Wyman

Fluids/ReservoirsTransport/depositional processesDeposit geology JLW/GEM SH/DIG/students/JLWMineralogy/ paragenesis JLW/GEM SH/DIG/students/JLWFluid inclusions JLW/GEM SH/DIG/students/JLWStable Isotopes JLW/GEM SH/DIG/students/JLWRadiogenic isotopes McNaughton / Carr

Hard ModellingSeal/reservoir /def/thermal/uplift Upton/GowSeal/res/def/therm/chamber/faults Upton/GowModels above with qtz ppt Upton/GowGas pressure/acidity Upton/GowReplicate above in 3D Upton/GowInversion of magnetic image/chamber CSIRO/Fractal Graphics

Code Development

Perm/por for modelling of seals Upton/Zhang

Partial link of EQ3/6 and Gibbsmodel gas pressure/acidity

Upton/ Semeniuk/JLW


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SPIRT LODE Au PROJECTI. GLOBAL- TO TERRANE- SCALE STUDIESObjectives:1. Establish models to explain why some orogens are gold-rich and others are gold-poor by placing

known deposits in the spatial and temporal context of (i) supercontinent aggregation and breakupand/or (ii) the global record of coeval tectonics and magmatism (Archean lode gold deposits).

2. Define exploration criteria to distinguish these different types of orogens by comparing theattributes of prospective and non-prospective terranes.

3. Provide guidelines for determining the location of prospective districts within favourable terranes.

Key Areas:1. Archaean: Yilgarn; Superior Province (highly and weakly prospective)2. Post-Archaean: Circum-Pacific

Personnel:

Derek Wyman, Stephen Gardoll (GIS Research Officer), David Groves, Mark Barley, Brian KrapezScientific Approach:GIS studies at two scales:1. Global Plate Reconstructions2. Terrane Focus Studies Incorporating Multiple Data Types:

Lithogeochemical data that fingerprints terrane geodynamic histories Data for gold mineralization and other deposit types that may define recurring geodynamic-

metallogenic associations

Terrane-scale structural data, Geochronological data that constrain individual deposit ages, establish terrane histories and

allow recognition of global patterns through time Geophysical data that reflect the orogenic histories of terranes

All CSMD terrane studies will be available for comparison and study in the GODS Project in order tomore rigorously establish prospective exploration criteria

Outcomes:Identification of prospective age spans and terrane types. Establishment of guidelines for selection ofprospective districts within prospective terranes. Development of sets of criteria for evaluation andprioritisation of poorly exposed or little-studied terranes.

II. DISTRICT-SCALE STUDIESObjectives:1. To establish those factors which are common to districts containing world-class orogenic gold

deposits within gold-rich orogens.2. In particular, to determine the relative roles of: 1) the regional-scale structural architecture of

the ore systems, 2) the nature of fluid reservoirs, and 3) the plumbing systems promotinganomalously high fluid flux, in determining the specific conjunction of factors which lead tothe generation of world-class orogenic gold deposits.


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Key Areas:1. Comparative province-scale comparative analysis of structural geometry of Yilgarn (including

sub-provinces), Zimbabwe, Abitibi and Pilbara.2. Yilgarn: Kalgoorlie, Sunrise and Wiluna goldfields vs smaller Yilgarn systems.3. Pine Creek: Howley and Howley Anticline vs smaller systems.4. Ghana: Projects at Damang and Prestea but may be confidentiality clauses.Personnel:

David Groves, Derek Wyman, Neal McNaughton, Carl Knox-Robinson, Juhani Ojala with input fromSteffen Hagemann and John Walshe. PhD students whose studies impact on the project include SusieBrown, Graeme Cameron, Jon Pigois, Orestes Santos, Eduardo Videla, and Grace Yun.

Scientific Approach:Two levels of research:

1. Province / District Scale Studies

Geometrical analysis of highly mineralised versus non-mineralised belts (eg. G. Yun) Regional syntheses based on non-confidential work in Africa (Ghana, Tanzania, Ethiopia);

Brazil (Tapajos); Australia (Yilgarn, Pine Creek, Victoria) by D. Groves2. District / Goldfield Scale Studies

GIS - based analysis of district, goldfields (eg. Wiluna, Howley) Modelling of hydrothermal plumbing systems at district scale (eg. Kalgoorlie, Sunrise?)

Outcomes:Identification of geometric and other parameters of highly mineralised belts with world-class depositsversus those poorly mineralised belts. Improved understanding of architecture of giant hydrothermalsystems at district scale. Derivation of quantitative models of such systems through interactions withCSIRO personnel.

III. DEPOSIT-SCALE STRUCTURAL, HYDROTHERMAL AND FLUIDCHEMISTRY CONTROLS

Objectives:1. Determine, through integrated structural and hydrothermal studies, the main factors, which

control the spatial occurrence of world-class gold deposits.2. In particular, to elucidate the structural and hydrothermal evolution of the deposits, reconstruct

the paleohydrothermal system in terms of P-T-X-t, and provide an integrated structural-hydrothermal and fluid chemistry model for the deposits.

Key Areas: (subject to negotiation)1. Wiluna lode-gold deposits, and Mt. Wilkinson lode-gold deposits in the Wiluna greenstone belt2. Tamoola gold deposits near Leonora, and3. Damang and Prestea mines in Ghana4. Sunrise

Personnel:

Steffen Hagemann, Ed Mikucki, David Groves, Postdoc (to be decided), PhD students Paul Duuring,Susie Brown, Graeme Cameron, Jon Pigois, other APA (I) (to be decided).


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Scientific Approach: Detailed mapping will be undertaken of open pits and/or underground workings

Alteration zonation and timing will be constrained in terms of petrography, whole rock andmineral chemistry

Fluid chemistry studies of gases, ions and metals will employ quadrupole mass-spectrometry andlaser-ICP-MS analyses on fluid inclusions.

Fluid sources will be constrained by a combination of stable, radiogenic isotopes and gas- andion-chromatography

Structural, petrographic and chemical work will then be integrated in order to provide adescriptive as well as genetic model for each deposit.

Outcomes:The study will establish (1) the structural control of lode-gold mineralization within specific orebodies, (2) petrographic and geochemical vectors towards high grade gold mineralization, and (3) aquantitative structural-hydrothermal model for each deposit. Results will be synthesised to define thestructural-hydrothermal architecture of giant lode-gold systems at the deposit scale.


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LARGE ARC FAULT ARCHITECTURE PROJECTObjectives:1. Establish the primary channelways for auriferous ore fluids, constrain the nature of hydrothermal

connectivity and the reasons (physical and/or chemical) for the lack of significant gold depositionin the crustal-scale structures.

2. To provide preliminary constraints on the total structural and hydrothermal history of the crustal-scale deformation zones in order to identify reactivation of earlier-formed structures during thegold mineralising events, post-gold fault movements, etc.

Key Areas:1. Archean Perseverance Fault in the northern Yilgarn Block of Western Australia, which is adjacent

to the well-studied Wiluna and Mt. Wilkinson deposits (Hagemann et al., 1995),2. the Cadillac Fault (Break) in Quebec, along which a number of well-studied world-class gold

deposits are sited (Robert and Brown, 1986), and3. the Mesozoic Fanshaw Fault System in Alaska, the site of the extensively documented Juneau

gold district (eg. Goldfarb, et al., 1986).Personnel:

UWA: Steffen Hagemann, David Groves, Postdoc (to be decided), Honours student (Daniel Bishop)in cooperation with the Quebec Geological Survey (Dr. Jean-Francois Couture), the United StatesGeological Survey (Dr. Richard Goldfarb), ETH Zurich (Dr. John Ridley), Leeds University (Prof.Bruce Yardley), University of Michigan (Prof. Steve Kesler), and University of Wisconsin (Prof. JohnValley).Scientific Approach:1. Detailed mapping of the fault systems, including paleostress analyses (Angelier, 1984)2. Whole-rock geochemical analyses of quartz veins and adjacent wallrocks to detect gold anomalies

to the ppb level)3. Thin section studies to determine siting of anomalous gold in veins or wallrocks4. Detailed quadrupole mass-spectrometry and laser-ICP-MS analyses, (including halogen analysis)

of vein fluids and laser-based oxygen isotope analyses on zoned quartz will be undertaken toconstrain the compositions, processes and source of the hydrothermal fluids.

Outcomes:Improved constraints will be placed on models to account for the lack of major gold deposits first-order structures. Relationships between crustal-scale fault movements and the evolution of complexvein systems will be established. Improved constraints will be placed upon the sources ofhydrothermal fluids, gold transport mechanisms and gold depositional processes.The results from this project will not be subject to the AMIRA confidentiality provisions that areapplicable to the GODS Research Program projects.


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COLLABORATION BETWEEN CSIRO, CODES, CSMD ANDINDUSTRYThe CODES Giant Porphyry Cu-Au project has been jointly devised in consultation with AMIRA,University of Western Australia, University of Tasmania and the relevant sponsor companies of theGiant Ore Deposits project (AMIRA P511). The project was discussed at AMIRA project P511sponsors meeting in March 1998 (Perth), where the sponsors indicated their support of the project,and indicated preferences for research directions. AMIRA, as research coordinators for theAustralian mineral industry, have been involved in several previous collaborative projects with theUniversity of Tasmania. As the AMIRA representative to the current project, the Industry Partner(Joe Cucuzza) will be responsible for managing the financial contributions from the industry sponsorsand distribution of annual reports, organising and chairing annual sponsors meetings, and forfacilitating technology transfer between the academic and industry groups. The PhD students,postdoctoral research fellow and (to a lesser degree) the chief investigator (Cooke) will spendconsiderable time on-site with the industry geologists during the field investigations. On-sitemeetings will be held at these times to discuss specific aspects of the projects will be discussed withcompany geologists. Each PhD student will have an industry supervisor, appointed by the companywho operates the mine where the student is studying. The sponsors will provide a total of $10K cashand $10K in-kind support for the APA-I students pa. ($5K each), and $37.5-39.5K towards the salaryof the postdoctoral research fellow pa., in addition to financial support for the analytical, travel andreporting costs. In-kind support will include local travel and accommodation on site, vehicle hire,sample bags, sample shipment and field assistance in sorting and laying out drill core for thepostdoctoral research fellow and APA-I students, and travel, accommodation and time for companyrepresentatives to attend sponsor meetings at the University of Tasmania (total $44K pa. in-kind,including APA-I contributions).

REPORTING, TECHNOLOGY TRANSFER & CONFIDENTIALITYThe end users of the outcomes of this project will be exploration geoscientists engaged in regional-scale mineral exploration. Reporting and technology transfer will be through the followingmechanisms:

Quarterly progress reports. Six-monthly meetings between research staff and company representatives.

Ad-hoc, informal technical meetings will be held to discuss specific technical questions realting tothe area under study. All sponsors are invited to participate in these meetings.

At the conclusion of the project a comprehensive final report will be issued describing the workdone and the conclusions reached.

Interim reports will be issued upon the completion of significant stages of the research.

Technology transfer workshops will also be held at appropriate juncture of the project.All material and information derived from the project will be treated as confidential and withheldfrom publication for a period of up to eighteen months after completion of the project and issuing ofthe final report to sponsors. Sponsors approval will be sought prior to the publication of anyinformation or findings derived from the project.Results that flow from projects other than AMIRA projects will nbot be subject to this provision.


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INTELLECTUAL PROPERTYIntellectual property generated during this project shall be available to all parties according to theconditions set out in the CSIRO-AMIRA-University standard collaborative research agreement. Therights and obligations of sponsors under this agreement are as follows: Each Sponsor Company has a non-exclusive, royalty free right to use in its own operations both

the Intellectual Property generated by a Project and so much of the Background Technologycontributed by the Researcher as is necessary to enable the Sponsor Company to so utilise theProject Intellectual Property.

Each Sponsor Company has the further right after written notice to AMIRA and the Researcher tosublicense that Intellectual Property to third parties solely for the purpose of enabling the SponsorCompany to utilise the Intellectual Property in its own operations and not for any other use by thethird party. The Sponsor Company bears all risk and responsibility arising from the granting ofsuch a sub-licence, without recourse to the Researcher.

Sponsor Companies have the further right to disclose Project Intellectual Property to relatedcompanies for evaluation only on terms of strict confidentiality and after written notice to AMIRAand the Researcher. Related Companies wishing to use such Intellectual Property must negotiate aseparate licence agreement with the Researcher.

For a period of eighteen months after completion of a Project, Sponsor Companies have the rightto request, and to participate in, any further research, development or commercialisation of theProject Intellectual Property on terms to be agreed.

The proceeds of any licensing of Project Intellectual Property by the Researcher are required to beshared with Sponsor Companies proportionately to their respective contributions.

Save as above, Sponsor Companies are bound by a strict duty of confidentiality which urvives thecompletion of the Project and the expiry of the Research Agreement and are required to ensurethat their employees and others to whom they are entitled to disclose Project Intellectual Propertyaccept a similar duty of confidentiality.

The standard AMIRA IP provisions above (1-6) will have to be agreed to by Monash Universityand the CSIRO prior to the initiation of the project.

REFERENCESClark, A.H., 1993, Are Outsize Porphyry Copper Deposits either Anatomically or Environmentally

Distinctive?: In Whiting, B.H., Hodgson, C.J., and Mason, R. eds, Giant Ore Deposits, Societyof Economic Geologists, Special Publication 2, p. 213-284.

Cooke, D.R., Heithersay, P.S., Wolfe, R., and Losada-Calderon, A., 1998a, Concepts and ExplorationCriteria for Australian and Western Pacific Porphyry Cu-Au deposits: AGSO Journal ofGeology and Geophysics (in press).

Cooke, D.R., Bull, S.W., Donovan, S., and Rogers, J.R., 1998b, K-metasomatism and Base MetalDepletion in the Settlement Creek and Gold Creek Volcanics, McArthur Basin, NorthernTerritory - Implications for Base Metal Mineralisation. Economic Geology (in press).

Dilles, J.H., and Einaudi, M.T., 1992, Wall-rock Alteration and Hydrothermal Flow Paths about theAnn-Mason Porphyry Copper Deposit, Navada - A 6km Vertical Reconstruction: EconomicGeology, v. 87, p. 1963-2001.

Gustafson, L.B., and Hunt, J.P., 1975, The Porphyry Copper Deposit at El Salvador, Chile: EconomicGeology, v. 70, p. 857-912.

Zentilli, M., Graves, M., Lindsay, D., Ossandon, G., and Camus, F., 1995, Recurrent Mineralization inthe Chuqicamata Porphyry Copper System: Restrictions in Genesis from Mineralogical,Geochronological and Isotopic Studies: In Clark, A.H., ed., Giant Ore Deposits II, Proceedingsof the Second Giant Ore Deposits Workshop, Kingston, Ontario, Canada, p. 90-113.

TERMS AND CONDITIONS

RELATING TO PARTICIPATION AS SPONSORS

1. AMIRA acts as agent for the Sponsors collectively to enter into an agreement on their behalfwith one or more Researchers to carry out the Research Project described in the proposal towhich these terms are attached.

2. Each Sponsor will pay to AMIRA its specified proportion of the operating budget for theResearch Project in the amounts and on the dates set out in the letter accompanying theproposal.

3. AMIRA will hold moneys received from each Sponsor on trust for that Sponsor fordisbursement in accordance with the Research Project Agreement. Pending suchdisbursement AMIRA may mix such moneys with its own moneys and with the moneys ofothers and may invest and earn interest on such moneys in any form of investment approvedby the Council of AMIRA. Any interest accruing from such investments shall belong toAMIRA to assist in defraying its expenses and operating costs generally.

4. Proportionately with all other Sponsors, each Sponsor will indemnify and keep indemnifiedAMIRA from and against all losses, claims, expenses, costs, actions, proceedings andliabilities sustained, suffered or incurred by AMIRA arising out of the Research Project andanything done or omitted by AMIRA as their agent, acting within the scope of its authority.

5. AMIRA will monitor the performance of the Research Project and keep the Sponsorsinformed of all material matters, including any developments likely to be useful to Sponsorsin relation to the subject matter of the Research Project.

6. AMIRA and each Sponsor shall keep confidential any information passing between them andthe Researcher in relation to the Project, save that Sponsors shall be entitled to discloseotherwise confidential information to related companies for the purpose of evaluation onsimilar terms of confidentiality. Furthermore, Sponsors shall ensure that their employees,officers and agents have agreed in writing, either generally as a term of their employment orspecifically in relation to the project, to maintain the confidentiality of all Project relatedconfidential information of which they become aware.

7. Both during and on completion of the Research Project, the rights of Sponsors to, and theirobligations in relation to, the Intellectual Property provided by other Sponsors or theResearcher or developed by the Researcher in the performance of the Research Project shallbe as set out in the Research Project Agreement.

SPONSOR COMPANIES RIGHTS AND OBLIGATIONSIN RESPECT OF INTELLECTUAL PROPERTY DEVELOPED

IN AMIRA RESEARCH PROJECTS

Companies which sponsor AMIRA research projects and members of AMIRA generally need to beaware of their rights and obligations in respect of Intellectual Property generated in CollaborativeResearch projects and made available to Sponsor Companies.

Following is a precis of the relevant provisions of the standard form Collaborative Research/LicenceAgreement used by AMIRA in contracting with Researchers on Sponsor Companies behalf.

Other than in exceptional cases of which due notice will be given, the following provisions will apply:

1. Each Sponsor Company has a non-exclusive, royalty free right to use in its own operations boththe Intellectual Property generated by a Project and so much of the Background Technologycontributed by the Researcher as is necessary to enable the Sponsor Company to so utilise theProject Intellectual Property.

2. Each Sponsor Company has the further right after written notice to AMIRA and the Researcher tosublicense that Intellectual Property to third parties solely for the purpose of enabling the SponsorCompany to utilise the Intellectual Property in its own operations and not for any other use bythe third party. The Sponsor Company bears all risk and responsibility arising from the grantingof such a sub-licence, without recourse to the Researcher.

3. Sponsor Companies have the further right to disclose Project Intellectual Property to relatedcompanies for evaluation only on terms of strict confidentiality and after written notice toAMIRA and the Researcher. Related Companies wishing to use such Intellectual Property mustnegotiate a separate licence agreement with the Researcher.

4. For a period of eighteen months after completion of a Project, Sponsor Companies have the rightto request, and to participate in, any further research, development or commercialisation of theProject Intellectual Property on terms to be agreed.

5. The proceeds of any licensing of Project Intellectual Property by the Researcher are required to beshared with Sponsor Companies proportionately to their respective contributions.

6. Save as above, Sponsor Companies are bound by a strict duty of confidentiality which survivesthe completion of the Project and the expiry of the Research Agreement and are required toensure that their employees and others to whom they are entitled to disclose Project IntellectualProperty accept a similar duty of confidentiality.

These provisions are designed to protect the interests of both Researchers and Sponsor Companies inrestricting the free availability of the technology to those who are directly involved. Apart from anyother consideration, the availability to sponsors of concessional deductions under S.73B of theAustralian Income Tax Act depends upon access to the technology being restricted in this way.

A contribution to:RELATIONSHIP OF CODES PROJECT TO AMIRA GODS RESEARCH PROGRAM P511GODS RESEARCH PROGRAM P511 - EXECUTIVE SUMMARYThe QuestionA holistic view of the ore systemSoft - hard model approach to developing mineral-systems concepts

PERSONNELDr. Carl Knox-RobinsonGeographical information systemsDr. Derek WymanEconomic geology, metallogenyDr. Ed MikuckiHydrothermal geochemistry

GIANT PORPHYRY COPPER-GOLD DEPOSITSGOALSIGNIFICANCERESEARCH PLANTIMETABLEBUDGET

HYDROTHERMAL SYSTEMS, GIANT ORE DEPOSITS & A NEW PARADIGM FOR PREDICTIVE MINERAL EXPLORATIONINTRODUCTIONTHE WORK PROGRAMSOFT - HARD MODELLING STUDIESA) Papua New Guinea - Irian JayaRegional architectureSize of systemStructureLithologiesIntrusive rocks

B) Northern Chile Regional StudyStructure

C) Kalgoorlie Regional Study

PROGRAM STRUCTURE AND FUNDINGDELIVERABLESTIMETABLEBUDGET (EXCLUDES THE CODES GIANT PORPHYRY CU-AU PROJECT)KEY PEOPLE FOR THE SOFT - HARD REGIONAL MODELLING

SPIRT LODE Au PROJECTGLOBAL- TO TERRANE- SCALE STUDIESDISTRICT-SCALE STUDIESDEPOSIT-SCALE STRUCTURAL, HYDROTHERMAL AND FLUID CHEMISTRY CONTROLSLARGE ARC FAULT ARCHITECTURE PROJECTCOLLABORATION BETWEEN CSIRO, CODES, CSMD AND INDUSTRYREPORTING, TECHNOLOGY TRANSFER & CONFIDENTIALITYINTELLECTUAL PROPERTYREFERENCES

Porphyry Cu Au

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