大红山铜矿床的地质特征及成矿作用演化

关于大红山矿床的成因,过去主要有变质热液富化的火山矿床,火山喷发(喷气)-沉积变质矿床,受变质火山喷气——沉积矿床等观点。本文研究表明,矿床为火山喷流热水沉积-变质-改造成因。成矿作用演化经历了火山喷流热水沉积,区域变质及后期改造三大成矿阶段。盖层中矿脉可作为基底隐伏矿床的预测标志。

GEOLOGICAL CHARACTERISTICS AND ORE-FORMING EVOLUTION OF DAHONGSHAN COPPER DEPOSIT

Dahongshan mine district is situated in the south-west end of Sichuan-Yunnan SN-tectonic belt. Na-rich basic volcanic-sedimentary metamorphic formation of Dahongshan group of Proterozoic era is discordantly covered by the "red bed" of Mesozoic era. The orebodies, occurring in vicinity of the volcano, are devided into three groups: volcanic exhalation hydrothermal sedimentary-metamorphic Fe-bearing copper orebodies, subvolcanic hydrothermal veined copper orebodies and reformative veined copper-polymetallic orebodies. The former occurs in the transitional belt from volcanic rocks to sedimentary rocks; While the latter occurs in the rift of the basement and cover rocks. The zoning of the deposit is clear, from the stratified ore to the reformed veined ore and veined ore from bottom to top, element constituent change from Cu,Fe(Co,Au) to Cu,Zn(Au,Ag) to Zn,Pb(Cu,Ag). The minerogenetic process involves three stages, namely, hydrothermal sedimentation, regional metamorphism and reformation after the metamorphism. The ore-forming metals of the veined ore in cover beds derives from the stratified ore and the ore-bearing volcanic formation in basement. The ore-veins in cover beds are the marks to the blind orebodies in basement.