黑龙江省砂宝斯金矿床成矿流体性质研究

    STUDY ON THE CHARACTERISTICS OF ORE-FORMING FLUID IN SHABAOSI GOLD DEPOSIT, HEILONGJIANG PROVINCE

    • 摘要: 砂宝斯金矿床产于中侏罗统陆相碎屑岩中,金矿体严格受S-N向和NNW向断裂构造控制.矿体石英中流体包裹体较为发育,以气液包裹体为主.通过流体包裹体的研究认为:成矿流体属于Ca2+(K+、Na+)-SO42-(F-、Cl-)型,具有低盐度(0.8%~9.2%)、低密度(0.895g/cm3)、偏碱性(pH8.05~8.26)、高硫低氧(LogfO2值为-39.4~-39.2)和相对还原环境(Eh值为-0.71~-0.68)的特点:成矿温度为200~230℃、成矿压力为17.24MPa,成矿深度为0.575km;成矿流体主要来源于深部岩浆,有部分大气降水加入,是岩浆热液和大气降水的混合流体;Au主要是以Au-S配合物的形式迁移,成矿流体的压力、pH值降低和Eh值升高是导致Au沉淀的重要因素.

       

      Abstract: The Shabaosi gold deposit occures in Middle Jurassic continental clastic rocks.The ore bodies are strictly controlled by S-N and NNW trending fault.Fluid inclusions in quartz are well developed, mainly in gas liquid phase.From the study of fluid inclusions, it is concluded that the ore-forming fluid belongs to Ca2+ (K+, Na+)-SO42- (F-, Cl-) type, which is characterized by the low salinity (0.8% to 9.2%), low density (0.895 g/cm3), alkali (pH 8.05-8.26), high sulfide, low oxidize (LogfO2-39.4 to-39.2) and reducing environment (Eh-0.71 to-0.68).The metallogenic temperature rangs from 200 to 230℃, with pressure of 17.24 MPa and depth of 0.575 km.The ore forming fluids are mainly derived from the deep magmas, with a little atmospheric water.Gold is transferred mainly in the form of gold-sulphur complex companion.The drop in pressure and pH value and promotion in Eh of the ore-forming liquid are important factors resulting in precipitation of gold.

       

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