四川尖山晶质石墨矿床碳同位素特征及成因  

Carbon isotope characteristics and genesis of the Jianshan scaly graphite deposit in Sichuan,China

作　　者：夏锦胜 孙莉[1,2,4] 司江福 汪君珠[3] 王洋 Xia Jinsheng;Sun Li;Si Jiangfu;Wang Junzhu;Wang Yang(Key Laboratory of Metallogeny and Mineral Assessment,Ministry of Natural Resources,Beijing 100037,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;Natural Resources Bureau of Liupanshui,Liupanshui 553000,Guizhou,China;Center of Metallogenic Regularity and Prediction,China Geological Survey,Beijing 100037,China)

机构地区：[1]自然资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质科学院矿产资源研究所,北京100037 [3]六盘水市自然资源局,贵州六盘水553000 [4]中国地质调查局矿产资源成矿规律与成矿预测研究中心,北京100037

出　　处：《地质学刊》2023年第1期8-12,共5页Journal of Geology

基　　金：中国地质调查局地质调查项目“全国矿产资源国情调查与综合评价(2022—2025)”(DD20221694)、“全国矿产资源潜力动态评价”(DD20160100);国家自然科学基金项目(41802250);国家重点研发计划项目(2016YFC0600504)。

摘　　要：四川尖山晶质石墨矿床大地构造位于扬子陆块区上扬子古陆块米仓山—大巴山基底逆冲带之米仓山基底逆冲带,是我国重要的晶质石墨矿床之一。为确定尖山晶质石墨矿床炭质来源和矿床成因类型,通过石墨矿C同位素测试,结合野外地质特征调查和矿物特征,综合分析认为尖山石墨矿床主要赋存在中元古界火地垭群麻窝子组中,矿区出露的吕梁期侵入岩体与麻窝子组呈侵入接触关系。石墨矿体主要赋存在麻窝子组白云岩内的构造角砾岩中,含矿岩石以含石墨构造角砾岩为主,含石墨片岩和含石墨白云质大理岩次之。石墨矿物多呈鳞片集合体状或不规则细脉状,大多数鳞片片径<0.15 mm。矿石固定碳质量分数在2.39%~17.72%之间,平均值为8.40%。石墨矿δ^(13)C测试值在-15.01‰~-19.96‰之间,平均值为-17.42‰,表明石墨炭质来源为有机碳。综合推测尖山石墨矿床为有机成因的接触变质-区域变质叠加复合型晶质石墨矿床。Jianshan scaly graphite deposit,one of the key graphite deposits in China,is located at the basement thrust belt of Micangshan of the basement thrust belt of Micangshan-Dabashan in the Upper Yangtze Block of the Yangtze Block.In order to determine carbon source and genesis types of the Jianshan scaly graphite,this paper integrates carbon isotope test of graphite deposits,field geological feature survey and mineral characteristics analysis,and concludes that the Jianshan graphite deposit mainly occurs in the tectonic breccia within the dolomite of the Mawozi Formation in Mesoproterozoic Huodiya Group.The main ore-bearing rocks are graphite-bearing tectonic breccia followed by graphite-bearing schist and graphite-bearing dolomitic marble.Graphite minerals are mostly in the form of scale aggregation or irregular veinlets.Most scales are less than 0.15 mm in diameter.The fixed carbon mass fraction of the ore ranges from 2.39% to 17.72%,with an average of 8.40%.The δ^(13)C values of the graphite ore range from -15.01‰ to -19.96‰,with an average of-17.42‰,indicating that the graphite carbon is derived from organic carbon.It is concluded that the Jianshan graphite deposit is contact-metamorphic-regional-metamorphic compound scaly graphite deposit of an organic genesis.

关 键 词：晶质石墨矿 地球化学特征 矿床成因 四川尖山 

分 类 号：P597.2[天文地球—地球化学] P619.252[天文地球—地质学]