the things that matter architecture and chemistry · pmd crc architecture and chemistry the things...
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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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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??
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
pmd CRCPorphyries and magnetitePorphyries and magnetite
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
?
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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)
pppredictiveredictiveredictive mmmineralineralineral dddiscoveryiscoveryiscovery
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