大兴安岭西坡比利亚谷银铅锌多金属矿床成因  

Genesis of Biliya Valley Ag-Pb-Zn Polymetallic Deposit on Western Slope of Great Xing’an Range

作　　者：梁小龙 孙景贵[1] 邱殿明 徐智涛 谷小丽 任泽宁[1] Liang Xiaolong;Sun Jinggui;Qiu Dianming;Xu Zhitao;Gu Xiaoli;Ren Zening(College of Earth Science,Jilin University,Changchun 130061,China;Editorial Department of Journal of Jilin University,Changchun 130026,China;Changchun Automobile Industry Institute,Changchun 130013,China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]吉林大学学报编辑部,长春130026 [3]长春汽车工业高等专科学校,长春130013

出　　处：《吉林大学学报（地球科学版）》2020年第3期781-799,共19页Journal of Jilin University：Earth Science Edition

基　　金：国家重点研发计划项目(2017YFC0601306);国家自然科学基金项目(41390444);中国地质调查局项目(DD20160344)。

摘　　要：比利亚谷银铅锌多金属矿床位于大兴安岭西坡的得尔布干成矿带,它是近些年来在该区新发现的一座大型银铅锌多金属矿床。该矿床矿体主要呈脉状、细脉浸染状、角砾状赋存于塔木兰沟组中-基性火山岩和满克头鄂博组酸性火山岩中的NW向断裂体系内。根据矿石的结构、构造以及矿物之间的共生组合、穿切关系,将成矿过程从早到晚划分为硅化石英+黄铁矿阶段(Ⅰ)、石英+黄铁矿+闪锌矿阶段(Ⅱ)、石英+黄铁矿+闪锌矿+方铅矿+辉银矿+黄铜矿±黝铜矿阶段(Ⅲ)、石英+黄铁矿+方解石+萤石±蛋白石阶段(Ⅳ);详细的石英、闪锌矿流体包裹体研究揭示:成矿早阶段(Ⅰ、Ⅱ)石英中发育WL型、C型包裹体,包裹体完全均一温度为188~254℃,盐度(w(NaCl))为1.83%~4.79%,密度为0.81~0.94 g/cm^3,属于中低温、低盐度的H2O-NaCl-CO2体系;成矿主阶段(Ⅲ)石英、闪锌矿中发育WL型包裹体,包裹体完全均一温度为160~188℃,盐度为3.69%~7.15%,密度为0.92~0.96 g/cm^3,属于低温、中低盐度的H2O-NaCl-CH4体系;成矿晚阶段(Ⅳ)石英中发育WL型、L型包裹体,WL型包裹体完全均一温度为130~165℃,盐度为1.22%~3.53%,密度为0.93~0.95 g/cm^3,属于低温、低盐度的H2O-NaCl体系。流体包裹体H-O同位素地球化学特征揭示:早阶段流体的δ18OH2O-SMOW值为-6.3‰^-5.9‰,δDH2O-SMOW值为-163.4‰^-162.7‰;成矿主阶段流体的δ18OH2O-SMOW值为-14.4‰,δDH2O-SMOW值为-165.4‰^-162.0‰;成矿晚阶段流体的δ18OH2O-SMOW值为-19.1‰,δDH2O-SMOW值为-150.7‰;硫化物Pb同位素比值分别为206Pb/204Pb=18.435~18.513、207Pb/204Pb=15.579~15.675、208Pb/204Pb=38.283~38.603。这种特征揭示,该矿床成矿流体为低温、低盐度的H2O-NaCl-CH4体系,早期为残余岩浆水和大气降水混合、中-晚期大气降水逐渐增加;成矿物质源于壳幔混合源区;成矿过程以流体混合方式导致成矿元素聚集和沉淀,矿床成因类型为与陆相火Biliya Valley Ag-Pb-Zn deposit is located in the Derbugan metallogenic belt on the western slope of Great Xing’an Range,which was discovered in recent years.The orebody types are vein,veinlet disseminated,and breccia.The ore bodies occur mainly in the Middle Jurassic intermediate-basic volcanic rocks of Tamulangou Formation and the felsic volcanic rocks of Manketouebo Formation,and are controlled by the NW-extending faults.According to the mineral association,ore fabric,and vein body interpenetration,the ore formed in four stages:silicified quartz+pyrite stage(Ⅰ),quartz+pyrite+sphalerite stage(Ⅱ),quartz+pyrite+sphalerite+galena+argentite+chalcopyrite±tetrahedrite stage(Ⅲ),and quartz+pyrite+calcite+fluorite±opal stage(Ⅳ).The study on the fluid inclusions(FIs)of quartz and sphalerite shows that the FIs in quartz of the early stages(ⅠandⅡ)are composed of liquid-rich(WL type)and CO2–H2O(C type)types.Their homogenization temperature,salincty,and density vary from 188 to 254℃,1.83%to 4.79%,and 0.81 to 0.94 g/cm^3 respectively,and the fluid in this stage belongs to H2O-NaCl-CO2 system with low temper ature and medium-low salinity.The FIs in quartz and sphalerite of the main stage(Ⅲ)are composed of liquid-rich(WL type)type,their homogenization temperature,salincty,and density vary from 160 to 188℃,3.69%to 7.15%,and 0.92 to 0.96 g/cm^3 respectively,and the fluid in this stage generally belongs to H2O-NaCl-CH4 system with medium-low temperature and low salinity.The FIs in quartz of the late stage(Ⅳ)are composed of liquid-rich(WL type)and liquid(L type)types,their homogenization temperature,salincty,and density vary from 130 to 165℃,1.22%to 3.53%,and 0.93 to 0.95 g/cm^3 respectively,and the fluid in this stage generally belongs to H2O-NaCl system with low temperature and low salinity.The hydrogen-oxygen isotope geochemical characteristics of fluid inclusions reveal that theδ18OH2O-SMOW andδDH2O-SMOW values of ore-forming fluids in the early stages vary from-6.3‰to-5.9‰and-163.4‰to-162.7�

关 键 词：流体包裹体 H-O-Pb同位素 比利亚谷银铅锌多金属矿床 内蒙古 

分 类 号：P618.42[天文地球—矿床学]