青海双朋西金铜矿床成矿模式研究

Research on Metallogenic Model of Shuangpengxi Gold Copper Deposit in Qinghai

双朋西金铜矿床位于西秦岭同仁-泽库成矿带,矿体呈透镜状、似层状产于印支期花岗闪长岩与石炭—二叠纪甘家组碳酸盐岩的外接触带矽卡岩中,是典型的矽卡岩型金铜矿床。矿石金属矿物以磁黄铁矿、黄铁矿、黄铜矿和褐铁矿为主;脉石矿物以石英、方解石、透闪石和透辉石为主。成矿作用经历了矽卡岩期、石英-硫化物期和表生作用期。稳定同位素研究表明:δD为-56‰～-49‰,δ18O为+9.2‰～+9.4‰,成矿流体为岩浆水,δ34S为+5.1‰～+6.6‰,显示S主要来源于深部岩浆。δ13C为-8.9‰～-8.4‰,代表δ13C主要来源于深部岩浆。依据矿床地质特征,结合同位素地球化学特征,初步建立了双朋西矽卡岩型金铜矿成矿模式,对该地区找矿评价工作具有一定的借鉴意义。

Shuangpenxi gold copper deposit is located in Tongren-Zeku metallogenic belt of Western Qin- ling. The ore bodies occurred in the outer contact skarn zone between Indosinian granodiorite and Carboni- ferrous-Permian Ganjia Formation carbonate. It is one of the typical skarn deposits. Metallic minerals in the ore include mainly pyrrhotite, pyrite, chalcopyrite, limonite, while gangue mineral are mainly quartz, calcite, tremolite, diopside. Ore-forming processes have experienced three stages of mineralization, skarn, quartz-sulfide and supergene. Research of stable isotope geochemistry of the ores indicates, δD varyingfrom -56% to -49%0, δ18O varying from ＋9.2%0 to ＋9.4%0, implying that ore-forming fluids are mag- marie water, δ34S vary from ＋5.1%0 to ＋6. 6%0, suggests sulphur is derived from magma in depth. 813C vary from --8. 9%0 to --8. 4%0, indicating 313C is derived from deep magma. Skarn metallogenic model of Shuangpengxi gold copper deposit has been built initially combining geological characters, which has some useful significance to the ore prospecting work in the area.