Origin of Sulfur in Some Magmatic-Hydrothermal Ore Deposits of South China

摘要

Mill concentrates of ore sulfides from three magmatic-hydrotherml ore deposits were studied for delta~(34)S at the granite-hosted Xihuashan deposits, and carbonate-hosted Shizhuan and Huashaping deposits. These ore deposits occur in the South China Fold System, which is composed of mid-Paleozoic "miogeosynclinal" sediments dominant in carbonates toward the Devonian age. Averages of the ore sulfides are -0.9 permil for the Xihuashan, +7.0 permil for the Shizhuan and +13.2 permil for the Huashaping deposits. Endogranitic ore sulfur of the Xihuashan and the Shizhuan deposits are considered magmatic, derived from by ca.+2 per thousand delta~(34)S granitic magma, but the carbonate-hosted ore sulfurs at the major part of the Shizhuan and Huashaping deposits are much higher than those expected from rock sulfur delta~(34)S values of the Yanshanian granites of the South China Fold System. Thus, addition of ~(34)S-enriched sulfur into the ore solutions is considered. Devonian and Carboniferous carbonates of the South China Fold System are very high in the delta~(34)S values of structurally substituted sulfate (SSS) sulfur, averaged as +25.7 and +15.7 permil, respectively, which are higher than the reported values from other areas of these ages. The SSS contents of the Paleozoic carbonates are very low at present, but recent carbonates contain typically 0.1 to 1 percent equivalent sulfate. The very low SSS contents in the wall rock carbonates and high delta~(34)S values in the ore sulfides may have been resulted from carbonate SSS extracted during recrystallization and some-how mixed with magmatic ore fluids when the granitic magmas intruded, then precipitated as the ore sulfides.