The ore fluids which produced Archaean lode-gold deposits in sub-amphibolite facies rocks of the Yilgarn Block, Western Australia, are characteristically low- to moderate-salinity H2O-CO2-CH4 fluids. Wall-rock alteration and ore deposition were from a generally reducing, near-neutral fluid at 200-350-degrees-C and 1-3 kbar, although more oxidising fluids produced some assemblages in the giant Golden Mile deposit. Gold was transported as reduced-sulphur complexes. The ore fluid composition and stable and radiogenic isotope data indicate multiple sources for the fluid and solute. Deep plumbing systems are invoked, with the fluids being either metamorphic fluids that derived solutes from the lower and upper crusts, or fluids exsolved from deep-seated granitoids formed by anatexis of such crust.
机构:
Department of Geology and Geophysics, University of Wisconsin, 1215 W. Dayton St., Madison, WI 53706, United StatesDepartment of Geology and Geophysics, University of Wisconsin, 1215 W. Dayton St., Madison, WI 53706, United States
Hagemann, Steffen G.
Brown, Philip E.
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机构:
Department of Geology and Geophysics, University of Wisconsin, 1215 W. Dayton St., Madison, WI 53706, United StatesDepartment of Geology and Geophysics, University of Wisconsin, 1215 W. Dayton St., Madison, WI 53706, United States
Brown, Philip E.
European Journal of Mineralogy,
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: 937
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