陕西西沟钼矿床辉钼矿Re-Os年代学和同位素地球化学特征及其地质意义  

Molybdenite Re-Os gochronology and isotope geochemical characteristics of Xigou molybdenum deposit in Shaanxi Province and its geological significance

作　　者：杜芷葳 叶会寿[2] 毛景文[2] 孟芳 曹晶[1] 王鹏[1] 魏征 丁建华[2] DU ZhiWei;YE HuiShou;MAO JingWen;MENG Fang;CAO Jing;WANG Peng;WEI Zheng;DING JianHua(School of Earth Sciences and Mineral Resources,China University of Geosciences,Beijing 100083,China;Key Laboratory of Metallogeny and Mineral Assessment,Ministry of Natural Resources,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;College of Gemology,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京100037 [3]中国地质大学珠宝学院,北京100083

出　　处：《矿床地质》2020年第4期728-744,共17页Mineral Deposits

基　　金：中国地质科学院矿产资源研究所项目(编号:YYWT-201713);国家自然科学基金(编号:41972094);全国矿产资源潜力动态评价项目(编号:DD20190193)联合资助。

摘　　要：西沟钼矿床是东秦岭黄龙铺地区近些年新发现和勘查的碳酸岩脉型钼矿床。钼矿体主要赋存于新太古界太华群变质岩内的石英方解石碳酸岩脉中,呈脉状、似层状或透镜状产出。辉钼矿主要呈浸染状、薄膜状、团块状分布于石英方解石碳酸岩脉中,成矿有关的围岩蚀变有钾长石化、硅化、黄铁矿化、萤石化、硬石膏化等。为查明西沟钼矿床的成矿时代、成矿物质来源、成矿机制、确定矿床类型,文章开展了辉钼矿Re-Os同位素测年,同位素地球化学分析。6件辉钼矿样品Re-Os同位素测年结果,模式年龄为(222.3±3.4)Ma^(226.6±3.7)Ma;加权平均年龄为(225.1±1.4)Ma;等时线年龄为(224.6±9.1)Ma,表明该矿床形成于晚三叠世。硫化物和硫酸盐的S同位素组成、重晶石和方解石Sr-Nd同位素组成及方解石C-O同位素组成均指示:西沟钼矿的成矿物质可能主要来源于地幔。根据其与华北陆块南缘其他碳酸岩型钼矿床地质特征、成矿时代和成矿物质来源等对比,确定西沟钼矿床属碳酸岩型脉状矿床。成矿作用发生于扬子板块与华北板块碰撞造山的后碰撞伸展环境,由于软流圈物质上涌诱发富集岩石圈地幔发生低程度部分熔融,所形成的碳酸质流体携带钼等成矿物质上升,在NW-NWW向深断裂带沉淀富集成矿。The Xigou molybdenum deposit is a carbonate dyke molybdenum deposit in the Huanglongpu orefield of eastern Qinling.It was discovered and explored in recent years.The molybdenum orebodies mainly occur in the quartz calcite carbonate veins with the host rocks being the Neoarchean Taihua Group.Molybdenite is mainly disseminated,thin-film and lump-like form in the quartz calcite carbonate veins.The host rocks have experienced such alterations as K-feldspar alteration,silicification,pyritization,fluoritization,and anhydrite alteration.The Re-Os isotope dating of six molybdenite samples shows that six model ages range from(222.3±3.4)Ma to(226.6±3.7)Ma,the weighted mean age is(225±1.4)Ma and the isochron age is(224.6±9.1)Ma,indicating that the deposit was formed in the Late Triassic.S isotopic composition of sulfide and sulfate,Sr-Nd isotopic composition of barite and calcite and C-O isotopic composition of calcite collectively imply that the ore-forming material of the Xigou molybdenum deposit may have mainly come from the mantle.The Xigou molybdenum deposit is a carbonate vein deposit according to its geological characteristics,metallogenic age and metallogenic material source in comparison with other carbonate molybdenum deposits in the Eastern Qinling.

关 键 词：地球化学 碳酸岩脉型矿床 辉钼矿RE-OS定年 S-Sr-Nd-C-O同位素组成 西沟钼矿床 东秦岭 

分 类 号：P618.65[天文地球—矿床学]