Lead isotopic characteristics of the xikuangshan superlarge Sb deposit and their geological implications

摘要

The Xikuangshan Sb ore deposit located in the central part of Hunan Province, China, is the only super-large Sb deposit so far reported int eh world, and is titled as the antimony capital of the world. The strata exposed int he Xikuangshan orefield are only Devonian to Permian Series. Except for a lamprophyre dyke seen in the eastern part, no igneous rocks outcrop within or around the mining district. Orebodies occur dominantly in the Devonian Shetianqiao Formation (D_(3s)) and subordinately in the Qiziqiao Formation (D_(2q)). The orebodies usually appear stratiform and stratoid in shape and are rather constant in both thickness and grade. The compositions of ores are simple. The metallic mineral is stibnite and the gangue minerals include quartz and calcite, with minor amounts of fluorite, barite and secondary gypsum. The ores are dominated by the quartz-stibnite type, the quartz-calcite-stibnite type and the calcite-stibnite type. The wall-rock alterations are predominated by silicification and subordinately by carbonatization and, to a lesser extent, baritizationand fluoritization.