Sian Nichols*, Honours New Celebration. Kate Moran, Honours

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1 The Things that Matter Architecture and Chemistry Peter Neumayr, John Walshe, Steffen Hagemann

2 Glen Masterman Kanowna Belle Masterman, Embedded Researcher Louis Gauthier, PhD Golden Mile Sian Nichols*, Honours New Celebration Mehrdad Heydari, PhD Ultramafic Rocks Joanna Hodge, PhD Alteration-Fluid Framework Kate Moran, Honours St Ives Fire Brigade Peter Neumayr John Walshe Steffen Hagemann Leo Horn, Embedded Researcher St Ives 2004 Susan Drieberg Wallaby Drieberg, Embedded Res.

3 predictive redictive ineral iscovery Goal: Goal More Cost effective Method: Method exploration Answer 5 Questions Kalgoorlie-Kambalda Key Themes: Laverton Scale integrated structural-hydrothermal Scale Integrate alteration models Quantitative Chemical gradients Contrasting fluid systems Understanding Empowered by embedded researchers on site and University-based research and training Eastern Goldfields

4 Aim: Develop Ore Systems View of Goldfields 5 QUESTIONS: AGCRC heritage Architecture Geodynamic Reservoirs Fluids drivers Transport /deposition

5 predictive Architecture of depositional site & intrusive complexes Seal Mixing Box Au?? Au?? Integrate upper crustal architecture with deep-crustal architecture

6 predictive Blewett, pmd2003 CRC

7 3D Architectural controls on reservoirs fluid pathways, chemical gradients Challenge: District - Terrane Scale Models

8 KB: Felsic Hosts; SIG: Mafic Hosts predictive Redox Range of Alteration Redox(log fo2) SO2g - H2Sg HSO4 -H2S Hematite Magnetite CO2g-CH4g Oxidized Fluids Volatiles Oxidized Magmatic Volatiles SIG: Fsp-Au High V/Al in magnetite Low V/Al in magnetite SIG: Wallrock approx. SIG: Ep Magnetite Po KB: V-rich Phengite+/- Fsp Reduced Fluids Sum S { log(h2s+sulfate) } Pyrrhotite Hematite Pyrite KB: Fsp +/-V-poor Phengite Pyrite 400ºC, 500 bars

9 predictive Early Epidote-Carbonate Carbonate- Magnetite Alteration WR GC carb ep fsp un Ep-carb-mag 0 carb ep fsp un Te Sr 400 Fsp-carb-py-Au Au Na Te Bi 0 carb ep fsp un associated with porphyries pre-dates gold Bi-tellurides Sr-rich, Na-poor St. Ives

10 predictive Exploration: Te-Au Most Te separate event to Au But spatially similar Te still good proxy for Au St. Ives Au Te Down Hole Depth (m) LD LD7113A LD70026A

11 predictive Early Epidote-Carbonate Carbonate-Magnetite Alteration FC (PIXE) Zn 50 Ca K 0 Ep-Mag Syn-Au Cu 6000 Ep-Mag Syn-Au Sr 3000 Fe Sr St. Ives Ca

12 predictive Fsp-Carb Carb-Py-Au alteration WR GC Albite bio chl chl_bio no 25 Size of symbol indicates Au grade bio chl chl_bio no 20 Na.Al Cs K.Al St. Ives Muscovite 0 K feldspar Fe/(Fe+Mg) 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 biotite

13 Au 10 ppm Probed Chlorite Compositions 200 Fe/Fe+Mg Depth(m) CD10095W2 (Conqueror) Au Grades correlate with zoning in chlorite compositions picked up by PIMA PIMA

14 KB: Felsic Hosts; SIG: Mafic Hosts predictive Redox Range of Alteration Redox(log fo2) SO2g - H2Sg HSO4 -H2S Hematite Magnetite CO2g-CH4g Oxidized Fluids Volatiles Oxidized Magmatic Volatiles SIG: Fsp-Au High V/Al in magnetite Low V/Al in magnetite SIG: Wallrock approx. SIG: Ep Magnetite Po KB: V-rich Phengite+/- Fsp Reduced Fluids Sum S { log(h2s+sulfate) } Pyrrhotite Hematite Pyrite KB: Fsp +/-V-poor Phengite Pyrite 400ºC, 500 bars

15 predictive redictive ineral iscovery Porphyries and magnetite

16 predictive redictive ineral iscovery Redox-mapping DFD KSL Magnetite (no seds) Magnetite? Porph. Extremely reduced? DCB KAM PBS * Pyrrhotite Pyrrhotite (no seds) BFS LUN 2km. Porph.? Reduced Exploration near mine

17 predictive Exploration district scale 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) Mapping with PIMA, bottom of hole geochemistry 2 km Kanowna Belle

18 predictive Whole-rock and Fluid Chemistry - Concept Whole-rock geochemical analysis Fluid analysis KB_Reg_PIMA_modify by mica_xt 5 to 14.2 (157) 2 to 5 (554) 1 to 2 (550) 0 to 1 (488) 1km INPUT Geochemical Modelling Genetic Model Exploration Model

19 predictive Conclusions Spatial and temporal variations in fluid chemistry Gradients win!!! Map flow paths & reservoirs Build Scale Integrated Models!!! Tools: Alteration mapping (PIMA, Core Logger) Whole-rock geochemistry Isotopes S,C & O