Multiple sulfur isotopes monitor fluid evolution of an Archean orogenic gold deposit

摘要: Abstract The evolution of a gold-bearing hydrothermal fluid from its source to the locus gold deposition is complex as it experiences rapid changes in thermochemical conditions during ascent through crust. Although well established that orogenic deposits are generated time periods abundant crustal growth and/or reworking, and processes control precipitation remain poorly understood. In situ analyses multiple sulfur isotopes offer new window into relationship between reservoirs Au-bearing fluids occur along their pathway final site mineralisation. Whereas δ34S able track thermodynamic ore-forming fluids, Δ33S virtually indelible can uniquely fingerprint an Archean sedimentary reservoir has undergone mass independent fractionation (MIF-S). We combine these two tracers (δ34S Δ33S) characterise laminated quartz breccia ore zone sulfide-bearing alteration halo (+6 Moz Au) structurally-controlled Waroonga deposit located Eastern Goldfields Superterrane Yilgarn Craton, Western Australia. Over 250 gold-associated sulfides yield shift what interpreted early pre-mineralisation phase, with chalcopyrite-pyrrhotite (δ34S = +0.7‰ +2.9‰) arsenopyrite cores (δ34S = ∼−0.5‰), syn-mineralisation stage, reflected rims (δ34S = −7.6‰ +1.5‰). This coincides unchanging value (Δ33S = +0.3‰), both temporally throughout Au-hosting sulfide paragenesis spatially across Au zone. These results indicate at least partially recycled MIF-S-bearing sediments. Further, invariant nature observed MIF-S signature demonstrates derived homogeneous depth, rather than being locally sourced precipitation. Finally, by constraining fixed reservoir, we display space capture abrupt change oxidation state causes Our highlight importance order elucidate any given fluid.