安徽铜陵冬瓜山层控矽卡岩铜矿床形成过程——来自磁黄铁矿的证据

Forming Process of Dongguashan Stratabound Skarn Cu Deposit in Tongling,Anhui Province—Evidence from Pyrrhotite

冬瓜山铜矿床是安徽铜陵地区代表性的层控矽卡岩型铜矿床之一,磁黄铁矿是冬瓜山铜矿床中广泛分布的矿石矿物。野外调研与矿相学观察显示,该矿床中的磁黄铁矿矿石具有沉积、热变质和热液交代结构构造。矿物学研究表明,不同矿石中的磁黄铁矿成分差异较大,其Fe含量变化于57.78%～60.67%之间,分属高温六方相和低温单斜相,主要由黄铁矿变质脱硫而成。冬瓜山铜矿的形成可能经历了早期沉积作用、中期热变质作用和晚期岩浆热液交代作用等复杂成矿过程。

Dongguashan copper deposit is one of representative stratabound skarn Cu deposits in Tongling,Anhui Province,and pyrrhotite is a type of ore minerals widely distributed in the deposit.Field investigation and microscopic observation indicate occurrence of sedimentary,thermally metamorphic,and hydrothermal metasomatic textures and structures in pyrrhotite ores from the deposit.Mineralogic study shows large difference in composition of pyrrhotite from the different ores,with Fe content ranging from 57.78% to 60.67%.There occur hexagonal（high-temperature） and monoclinic（low-temperature） pyrrhotite mainly formed by desulfurization of pyrite.A complex metallogenic process of early sediment and middle thermal metamorphism followed by late magmatic hydrothermal metasomatism may be responsible for the formation of the Dongguashan copper deposit.