SHRIMP S-ISOTOPE EVIDENCE FOR FLUID MIXING DURING GOLD MINERALIZATIONIN A SLATE-BELT GOLD DEPOSIT (HILL-END, NEW-SOUTH-WALES, AUSTRALIA)

Sensitive high-resolution ion microprobe (SHRIMP) sulfur isotope data show that pyrrhotite, pyrite, galena and chalcopyrite in syntectonic a uriferous quartz veins at the Hill End goldfield are characterized by two populations, with delta(34)S(fluid)-values of similar to +7 and si milar to 0 parts per thousand. These two populations are accounted for by fluid mixing involving two sources of sulfur during evolution of t he vein systems. A local sulfur source and reduced fluids derived from trough-fill Siluro-Devonian sedimentary and volcanosedimentary sequen ces are responsible for the first two gold-bearing events, whereas a m ore oxidized fluid and a sulfur source from turbidites and volcanics i n deeper parts of the crustal sequences appear responsible for gold de position late in the second gold-forming event and are the dominant in fluences in the final gold-forming stage. For fine-grained mixtures, w here mineral separation is difficult, the SHRIMP analyses are particul arly useful for tracing derailed delta(34)S variations of sulfides pre cipitated in different paragenetic stages.