Multi-stage evolution of a gold mineralization from southern China: Implications for the ore-forming processes

Abstract

The Jinshan gold deposit is hosted in the Neoproterozoic metasedimentary rocks in the central part of the Jiangnan Orogen in southern China. Multiple generations of arsenopyrite and pyrite were formed: Stage 1 arsenopyrite- pyrrhotite, Stage 2 quartz–arsenopyrite–gold and Stage 3 quartz–carbonate–pyrite. Here, we present in situ major element, trace element, trace element mapping, and in situ sulfur isotope analyses of sulfides. Gold enrichment is not dependent on As, but may be transmitted through the low melting chalcophile element (LMCE) such as Pb, Bi, Sb, Te. The ore-forming fluids of gold mineralization were likely derived from a magmatic source. We analyze the detailed enrichment process that the early fluid has low contents of Au but as a result of decreasing in temperature the ore-forming fluids; the dissolution and reprecipitation process of arsenopyrite caused by late magmatic-hydrothermal fluid with elevated Au content led to the local change of fo₂ in the fluid, thereby promoting the release of Au.