The Things that Matter Architecture and Chemistry · pmd CRC Architecture and Chemistry The Things...

pmd CRC

Architecture and ChemistryArchitecture and ChemistryThe Things that MatterThe Things that Matter

Peter Neumayr, John Walshe, Steffen Hagemann

Glen Glen MastermanMasterman, , Embedded ResearcherEmbedded ResearcherKanownaKanowna BelleBelle

Joanna Hodge, Joanna Hodge, PhDPhDAlterationAlteration--Fluid FrameworkFluid Framework

MehrdadMehrdad HeydariHeydari, , PhDPhDUltramaficUltramafic RocksRocks

Leo Horn, Leo Horn, Embedded ResearcherEmbedded ResearcherSt IvesSt Ives

Kate Moran, Kate Moran, HonoursHonoursSt IvesSt Ives

Sian Nichols*, Sian Nichols*, HonoursHonoursNew CelebrationNew Celebration

Louis Gauthier, Louis Gauthier, PhDPhDGolden MileGolden Mile

Fire BrigadeFire BrigadePeter Peter NeumayrNeumayrJohn John WalsheWalsheSteffen Steffen HagemannHagemann

20042004Susan Susan DriebergDrieberg, , Embedded Res.Embedded Res.WallabyWallaby

pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery

pmd CRC

Eastern GoldfieldsEastern Goldfields

GoalGoal:More Cost effective More Cost effective explorationexplorationMethodMethod:•• Answer 5 Questions Answer 5 Questions

•• KalgoorlieKalgoorlie--KambaldaKambalda•• LavertonLaverton

•• Scale IntegrateScale Integrate•• Quantitative Quantitative

UnderstandingUnderstanding

•• Empowered by embedded Empowered by embedded researchers on site and researchers on site and UniversityUniversity--based research and based research and trainingtraining

Key Themes:

• Scale integrated structural-hydrothermal alteration models

• Chemical gradients• Contrasting fluid systems

Aim: Develop Ore Systems View of Goldfields

5 QUESTIONS: AGCRC heritage• Architecture• Geodynamic• Reservoirs • Fluids drivers • Transport /deposition


pmd CRC

Architecture of Architecture of depositional site &depositional site &intrusive complexesintrusive complexes

Integrate upper Integrate upper crustal architecture crustal architecture with deepwith deep--crustalcrustalarchitecturearchitecture

Mixing Box Mixing Box

Au??

Seal

Au??


pmd CRCBlewett, 2003

3D Architectural 3D Architectural controls on controls on reservoirs fluid reservoirs fluid pathways, chemical pathways, chemical gradientsgradients

Challenge:Challenge:District District --Terrane Terrane Scale ModelsScale Models


pmd CRCRedox Range of AlterationRedox Range of Alteration

-28

-26

-24

-22

-3 -2.6 -2.2 -1.8 -1.4 -1 -0.6 -0.2

Sum S { log(H2S+sulfate) }

Red

ox(lo

g fO

2)

Oxidized MagmaticVolatiles

Reduced Fluids

High V/Al in magnetite

Low V/Al in magnetite

Pyrrhotite PyriteMagnetite Po

CO2g-CH4g

SO2g - H2Sg

HSO4 -H2S

HematiteMagnetite

Hematite

Pyrite

OxidizedFluids

Volatiles

SIG: Ep

SIG: Fsp-Au

SIG: Wallrock approx.

KB: V-rich Phengite+/- Fsp

KB: Fsp +/-V-poor Phengite

400ºC, 500 bars

KB: Felsic Hosts; SIG: Mafic Hosts


pmd CRC

0.00 0.05 0.10 0.15 0.20 0.25Na

0

200

400

600

800

Sr

0carbepfspun

Early EpidoteEarly Epidote--CarbonateCarbonate--Magnetite Alteration Magnetite Alteration –– WR GCWR GC

0 1000 2000 3000Au

0

5000

10000

15000

20000

25000

30000

Te

0carbepfspun

0 10 20 30 40 50Bi

0

5000

10000

15000

20000

25000

30000

Te

0carbepfspun

• associated with porphyries• pre-dates gold• Bi-tellurides• Sr-rich, Na-poor

1

2

3

Ep-carb-mag

Fsp-carb-py-Au

St. Ives


pmd CRCExploration: TeExploration: Te--AuAu• Most Te separate event

to Au• But spatially similar• Te still good proxy for Au 100

150200

250300

350

Dow

n Hole D

epth (m).

1000

12000

23000

LD7114

050

100150

200250

300

2000

6000

10000

LD7113A 280300

320340

360

400

1000

1600

LD70026A

AuTe

St. Ives


pmd CRCEarly EpidoteEarly Epidote--CarbonateCarbonate--Magnetite Magnetite Alteration Alteration –– FC (PIXE)FC (PIXE)

Ca K

Fe Sr

0 50 100 150Cu

0

50

100

150

Zn

Ep-MagSyn-Au

10000 30000 50000 70000Ca

0

1000

2000

3000

4000

5000

6000

Sr

Ep-MagSyn-Au

St. Ives


pmd CRCFspFsp--CarbCarb--PyPy--AuAu alteration alteration ––WR GCWR GC

0.2 0.4 0.6 0.8 1.0Fe/(Fe+Mg)

0

5

10

15

20

25

Cs

biochlchl_biono

0.0 0.2 0.4 0.6 0.8 1.0K.Al

0.0

0.2

0.4

0.6

0.8

1.0

Na.

Al

biochlchl_biono

Albite

K feldsparMuscovite

Size of symbol indicates Au grade

• Na/Al vs K/Al plots map out biotite/chlorite alteration zones

•Fe/(Fe+Mg) ratios map out Au-related biotite/chlorite: Au occurs with intermediate compositions

• Cs does not correlate with Au-related biotiteSt. Ives

Au

10 p

pm Probed Chlorite Compositions

200

250

300

350

400

0.25 0.3 0.35 0.4 0.45 0.5

Fe/Fe+Mg

Dep

th(m

)

CD10095W2 (Conqueror)• Au Grades correlate with

zoning in chlorite compositions picked up by PIMA

PIMAPIMA


pmd CRCRedox Range of AlterationRedox Range of Alteration

-28

-26

-24

-22

-3 -2.6 -2.2 -1.8 -1.4 -1 -0.6 -0.2

Sum S { log(H2S+sulfate) }

Red

ox(lo

g fO

2)

Oxidized MagmaticVolatiles

Reduced Fluids

High V/Al in magnetite

Low V/Al in magnetite

Pyrrhotite PyriteMagnetite Po

CO2g-CH4g

SO2g - H2Sg

HSO4 -H2S

HematiteMagnetite

Hematite

Pyrite

OxidizedFluids

Volatiles

SIG: Ep

SIG: Fsp-Au

SIG: Wallrock approx.

KB: V-rich Phengite+/- Fsp

KB: Fsp +/-V-poor Phengite

400ºC, 500 bars

KB: Felsic Hosts; SIG: Mafic Hosts


pmd CRCPorphyries and magnetitePorphyries and magnetite


pmd CRCRedoxRedox--mappingmapping

PBSPBS

DFDDFD

PorphPorph..DCBDCB

KAMKAM

PorphPorph..LUNLUN

MagnetitePyrrhotitePyrrhotite (no seds)*

Magnetite (no seds)

BFSBFS

2km.2km.

KSLKSL

Exploration “near mine”Exploration “near mine”

?

Extremely reduced?

Reduced

?


pmd CRC

KB_Reg_PIMA_modified by Chlorite_yFeOH

2,255 to 2,261.3 Fe-chlorite (170)2,250 to 2,255 Int-chlorite (615)2,245 to 2,250 Mg-chlorite (399)2,238.7 to 2,245 (97)

2 km

Exploration “district scale”Exploration “district scale”

Mapping with PIMA, bottom of hole geochemistryKanowna Belle


pmd CRCWholeWhole--rock and Fluid Chemistry rock and Fluid Chemistry -- ConceptConcept

Whole-rock geochemical

analysis

Fluid analysis

Geochemical Modelling

INPUTINPUT

Genetic Model

Exploration Model

1kmKB_Reg_PIMA_modify by mica_xt

5 to 14.2 (157)2 to 5 (554)1 to 2 (550)0 to 1 (488)


pmd CRCConclusionsSpatial and temporal variations in fluid Spatial and temporal variations in fluid

chemistry chemistry Gradients win!!!Gradients win!!!Map flow paths & reservoirsMap flow paths & reservoirsBuild Scale Integrated Models!!!Build Scale Integrated Models!!!

Tools: Tools: Alteration mapping (PIMA, Core Logger)Alteration mapping (PIMA, Core Logger)

WholeWhole--rock geochemistryrock geochemistryIsotopes S,C & OIsotopes S,C & O

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