On mineral exploration in the Emeishan flood basalt province

Abstract：Global correlation indicates that there occur three relatively complete magmatic-hydrothermal minerogenic series in the Emeishan flood basalt province. The outpouring conduits for fissure eruption of the Emeishan basalt was controlled by the discontinuity of the lithospheres revealed by the geochemical boundary. The preservation of a complete rock association of paleovolcanic vent facies in these districts provides an important clue to mineral exploration. There were three magmatic fractionation trends in magma chambers： sulfur-poor, low-orygen fugacity magma, sulfur-poor, high-oxygen fugacity magma and sulfur-rich magma, which produced three magmatic minerogenic series（Cu-Ni-PGE, Cu-Ag-Pd and Fe-Ti-V）. Synvolcanic-hydrothermal activity gave rise to copper minerogenic series from low greenschist and prehnite to zeolite facies (from 400℃ to100℃). Hydrothermal fluids of different compositions controlled the formation of native copper, copper oxides and copper sulfides. Comparison of the vitrinite reflectance R0 indicates that bitumen that played an important role in controlling native copper precipitation was derived from hydrothermal pyrolysis of organic matter at the P2-T1 boundary and that organic matter was at the mature stage for oil genesis. Therefore, a package exploration for Cu, Ni, Pt-Pd and petroleum can be launched, as is the case with the Midcontinent Rift in Michigan, United States.