金川铜镍硫化物矿床中富铜矿石铂族元素特征及矿床成因

金川铜镍硫化物矿床是世界单个矿体最大的镍矿床,镍资源储量居世界第三.矿床以海绵陨铁状矿石为主,富Cu矿石在矿床中呈"鸡窝状"产出.基于富Cu矿石的空间分布、矿石结构、硫化物组合、铂族元素地球化学的研究,提出了富Cu矿石的成因:硫化物发生单硫化物固溶体结晶,在重力分异或构造扰动下,富Cu、Pt、Pd的残余硫化物在局部聚集成矿.根据大量铂族数据的统计与模拟计算,获得了金川矿床母岩浆的PGE组成:Os=0.355×10-9,Ir=0.265×10-9,Ru=0.277×10-9,Rh=0.144×10-9,Pt=4.91×10-9,Pd=2.32×10-9,Ni=338×10-6,Cu=174×10-6.通过R因子与硫化物分异结晶过程模拟,金川铜镍硫化物矿床的R因子为300～1000,平均为567,R因子值在1号与24号矿体中明显大于2号矿体.

PGE Characteristics of Cu-rich Ores in the Jinchuan Cu-Ni Sulfide Deposit and Its Genesis

The Jinchuan intrusion hosts the largest single magmatic Ni deposit in the world.Net-textured sulfide ores are the main ore type,Cu-rich ores are nest-like distribution in the ore deposit.Spatial distribution,ore structure,composition of sulfide and PGE geochemistry of Cu-rich ores,the authors put forward its genesis: sulfide experiences Mono-Sulfide Solution (MSS) at later stage,the residual sulfide with Cu-,Pt-,Pd-rich concentrates at local space by gravity differentiation or tectonic activities.According to statistics and modeling of more than 300 PGE data,the PGE concentrations of the Jinchuan parental magma are concluded: Os=0.355×10-9,Ir=0.267×10-9,Ru=0.277×10-9,Rh=0.144×10-9,Pt=4.94×10-9,Pd=2.32×10-9,Ni=338×10-6,Cu=174×10-6.The average R factor of the Jinchuan ore deposit is 567,which is higher in ore body 1 and 24 than ore body 2.