新疆香山铜镍矿区热液作用性质及其成矿潜力研究

香山铜镍矿床位于东天山土墩-黄山-图拉尔根铜镍矿带中部,具有较好的铜、镍资源前景。矿区内热液作用发育,出现大量蚀变矿物、含金属硫化物的石英/方解石脉状矿石贯穿基性岩石。通过对蚀变矿物特征、石英/方解石中流体包裹体、金属硫化物成分等研究,探讨热液作用性质及其成矿意义。研究表明,岩石蚀变矿物主要为蛇纹石(两个世代)、纤闪石、绿泥石和黑云母等,说明热液流体具有多阶段特征,含有一定量的卤素挥发分;矿石蚀变矿物主要为针镍矿、紫硫镍矿、红砷镍矿、辉砷钴矿等,说明热液流体的硫逸度逐渐增高;脉状矿石中,石英/方解石中以富液相流体包裹体为主,其大小为4~12μm,气液比5~15%之间,均一温度峰值为200~240℃,表明热液流体具有中高温性质。在对比邻区热液矿床流体包裹体特征和硫同位素组成的基础上,认为香山铜镍矿区内热液作用可能为与含铜镍拉斑玄武质岩浆相关的中高温热液事件,它具有富集Pt、Ag和Au的潜力。

Characters of hydrothermal processes and their metallogenic potential in Xiangshan Cu-Ni deposit,Xinjiang

Xiangshan Cu-Ni deposit with good resource prospecting is located at the middle part of Tundun- Huangshan-Tulaergen Cu-Ni ore belt, eastern Tianshan. The hydrothermal processes are obvi- ously developed in the deposit, causing to form many altered minerals and sulfide-bearing quartz/calcite veins filling along fissures in basic rocks. In order to understand the characters of hydrothermal processes and their minerlization potential, the study on characteristics of alteration minerals, fluid inclusions in quartz/calcite minerals, EPMA of metallic sulfides has been carried in this paper. The result shows that serpentines （two stages）, uralites, chlorites and biotites are usually seen in the altered rocks, which infers that the hydrothermal fluids are characterized by multi-stage processes and some content of halogen vola- tiles in fluid system. The altered metallic sulfides include millerite, violarite, niccolite, cobaltine, which infers that sulfur fugacity of fluid is gradually increased. The fluid inclusions in quartz/calcite minerals of vein-like ores are dominated by primary liquid-rich type, whose sizes vary from 4-12 μm, and most of them are liquid-rich （vapor-liquid ratios arrange from 5-15%） except for lesser vapor-rich （vapor-liquid ratios are over 50%）. The homogenization temperatures of the fluid inclusions are between 200℃ and 240℃, indicating the features of high-middle hydrothermal fluids. Based on contrasts of fluid inclusions and sulfur isotopic compositions between hydrothermal ores in Xiangshan deposit and those in adjacent hy- drothermal deposit, it is suggested that the hydrothermal mineralization of Xiangshan Cu-Ni deposit may possibly be middle-high-temperature hydrothermal activity related with Cu-Ni-bearing tholeiitic magma, and the deposit possesses the potential of enrichment of Pt, Ag and Au.