河南省栾川县石窑沟钼矿床地质特征和流体包裹体研究

Study on Geology and Fluid Inclusions of the Shiyaogou Molybdenum Deposit,Luanchuan Country,Henan,China

为探讨石窑沟钼矿床的矿床成因,本文开展了系统的地质及成矿流体特征研究。根据矿脉穿切关系,将热液成矿过程分为早、中、晚3个阶段,其矿物组合分别为石英-钾长石-黄铁矿-辉钼矿、石英-多金属硫化物和石英-方解石±黄铁矿。研究发现,成矿早、中阶段产出的石英中有水溶液包裹体、纯CO2包裹体、H2O-CO2类包裹体和含子晶多相包裹体,而成矿晚阶段产出的石英中仅有水溶液包裹体;对不同阶段包裹体的显微测温和激光拉曼测试结果显示,成矿早阶段成矿流体以高温、高盐度、高氧化性、富CO2为特征;中阶段流体发生沸腾,导致CO2逃逸,还原性增强,成矿物质沉淀;晚阶段流体以低温、低盐度、贫CO2为特征。流体沸腾可能是引起辉钼矿沉淀的重要原因。

This paper systematically studied on geology and ore-forming fluids in the Shiyaogou molybdenum deposit and discussed the nature and evolution of the ore-forming fluids. According to the crosscutting relationship of ore veins,the hydrothermal ore-forming process can be divided into early,middle and late stages,in which the characterized mineral assemblages of the hydrothermal ore-forming fluid were quartz-potash feldspar-molybdenite-pyrite,quartz-polymetallic sulfides and quartz-calcite±pyrite,respectively. There four types of fluid inclusions,Na Cl-H2 O,pure CO2,CO2-H2 O and daughter mineral-bearing fluid inclusions were found in the quartz of the early and the middle stages,while only one type of fluid inclusions,Na Cl-H2 O inclusions,were found in the quartz of the late stage. Microscopic date,including compositions,homogeneity temperature and salinity,of fluid inclusions from different stages demonstrated that the early stage ore-fluids were characterized by high temperature,high salinity and high content of CO2,the middle stage ore-fluids underwent a rapid precipitation of ore-forming materials since of fluid boiling and CO2 releasing,and the late stage ore-fluids were characterized by low temperature,low salinity and low content of CO2. It implied that the fluid boiling process might be the dominant factor for molybdenite deposition.