pmd CRC Camp Camp - - to deposit to deposit - - scale spatial scale spatial zonation zonation and and temporal succession of temporal succession of redox redox indicator indicator sulphide sulphide - - oxide minerals oxide minerals - - vectors to vectors to Archaean Archaean orogenic orogenic gold gold deposits? An example from the St. Ives gold camp, deposits? An example from the St. Ives gold camp, Yilgarn Yilgarn Craton Craton , Western Australia , Western Australia Peter Neumayr 1 , Steffen G. Hagemann 1 , John Walshe 2 , Leo Horn 2 , Robert Morrison 3 1 Centre for Global Metallogeny, UWA 2 CSIRO, Division of Exploration and Mining 3 St. Ives Gold Mining Company Pty Ltd
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Camp- to deposit-scale spatial zonation and temporal ...Kalg. Group, Komatiite, Lunnon Kalg. Group, mafic rocks Kapai Slate M erougil B ds Gravity Lows Oxidized – Hematite – Magnetite
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pmd CRCCampCamp-- to depositto deposit--scale spatial scale spatial zonationzonation and and
temporal succession of temporal succession of redoxredox indicator indicator sulphidesulphide--oxide minerals oxide minerals -- vectors to vectors to ArchaeanArchaean orogenicorogenic gold gold deposits? An example from the St. Ives gold camp, deposits? An example from the St. Ives gold camp,
YilgarnYilgarn CratonCraton, Western Australia, Western Australia
Peter Neumayr1, Steffen G. Hagemann1, John Walshe2, Leo Horn2, Robert Morrison3
1 Centre for Global Metallogeny, UWA2 CSIRO, Division of Exploration and Mining3 St. Ives Gold Mining Company Pty Ltd
AcknowledgementsAcknowledgements
pmd CRCThe project is funded by the pmd*CRC and St. Ives Gold Mining Company Pty Ltd. (Gold Fields). Permission to publish is gratefully acknowledged.
• Camp is zoned with respect to redox conditions of hydrothermal fluids• Hydrothermal alteration forms at different times• Hydrothermal magnetite (oxidized fluid) rims gravity lows on camp scale
and has a strong spatial association with abundant porphyries• Hydrothermal hematite occurs typically within the gold lodes and late• Oxidized fluid are highly focussed (camp and deposit scale)• Pyrrhotite (reduced fluid) occurs in areas subjacent to magnetite
alteration• Reduced fluids are diffused (poorly focussed)• Redox state of hydrothermal alteration changes during Au precipitation• Redox shift occurred either through fluid mixing or through interaction