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现代地质 ›› 2022, Vol. 36 ›› Issue (06): 1486-1496.DOI: 10.19657/j.geoscience.1000-8527.2022.06.04

• 矿床学 • 上一篇    下一篇

四川坪河晶质石墨矿床地球化学特征及成因分析

夏锦胜1,2(), 孙莉1(), 张鹏3(), 陈昌阔4, 汪君珠2, 司江福2   

  1. 1.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
    2.六盘水市自然资源局,贵州 六盘水 553000
    3.山东省第五地质矿产勘查院,山东 泰安 271000
    4.贵州省地矿局 113地质大队,贵州 六盘水 553000
  • 收稿日期:2021-12-04 修回日期:2022-06-13 出版日期:2022-12-10 发布日期:2023-01-11
  • 通讯作者: 孙莉,张鹏
  • 作者简介:张鹏,男,高级工程师,1980年出生,地质调查与矿产勘查专业,从事区域矿产调查及矿产勘查评价工作。Email:zhang_6999@163.com
    孙莉,女,研究员,1981年出生,矿产普查与勘探专业,从事矿产资源评价工作。Email:sunli0727@163.com
    夏锦胜,男,硕士,1991年出生,矿物学、岩石学、矿床学专业,主要从事矿床地球化学研究、国土空间生态修复和地质灾害防治工作。Email: lpsszrzyj@163.com
  • 基金资助:
    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);国家自然科学基金项目(41802250);国家重点研发计划项目(2016YFC0600504);中国地质调查局地质调查项目“全国矿产资源潜力动态评价”(DD20160100)

Geochemical Characteristics and Genesis of Pinghe Crystalline Graphite Deposit in Sichuan Province

XIA Jinsheng1,2(), SUN Li1(), ZHANG Peng3(), CHEN Changkuo4, WANG Junzhu2, SI Jiangfu2   

  1. 1. MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China
    2. Natural Resources Bureau of Liupanshui,Liupanshui,Guizhou 553000,China
    3. Shandong Fifth Institute of Geology and Mineral Exploration,Taian,Shandong 271000,China
    4.113 Geological Party,Guizhou Bureau of Geology and Mineral Exploration,Liupanshui,Guizhou 553000,China
  • Received:2021-12-04 Revised:2022-06-13 Online:2022-12-10 Published:2023-01-11
  • Contact: SUN Li,ZHANG Peng

摘要:

四川坪河晶质石墨矿床大地构造位置位于扬子古陆块内的米仓山—大巴山基底逆冲带上,是中国重要的晶质石墨矿床之一。为研究其矿床成因,通过野外地质特征调查和矿物特征研究,结合含石墨变质岩系的地球化学特征分析可知,坪河晶质石墨矿床主要赋存在中元古界火地垭群麻窝子组地层中,矿体在平面、剖面上形态呈层状到不规则透镜状,矿体产状与围岩基本一致。主要含矿岩石为含石墨片岩,次为含石墨白云质大理岩,矿石平均固定碳含量16.32%;石墨矿物多呈鳞片状,其中大鳞片石墨(>0.15 mm)占37%,中小鳞片石墨(<0.15 mm)占63%;主量元素和微量元素分析结果表明: 坪河晶质石墨矿床含石墨变质岩系原岩为泥质粉砂岩,物源为陆源;锆石SHRIMP U-Pb测年结果显示含石墨片岩变质时代为新元古代(751.6±4.5) Ma;石墨矿δ13C测试平均值为-24.17‰,表明石墨的碳质来源为有机碳。综合推测坪河晶质石墨矿床成因为有机成因的区域变质矿床。

关键词: 四川坪河, 晶质石墨矿, 地球化学特征, 矿床成因

Abstract:

The Pinghe scaly graphite deposit,one of the crucial graphite deposits in China,located on the Micangshan-Dabashan thrust belt of upper Yangtze Block.Field survey,mineralogical and geochemical analysis of graphite bearing metamorphic rocks were carried out to study the ore genesis of this deposit.The ore bodies are hosted in the Mawozi Formation of the Mesoproterozoic Huodiya Group.The ore bodies which conform to the wall rocks mainly display bedding to lenticular occurrence.The host rocks of the deposit are mainly graphite schists and minor graphite bearing dolomotic marbles.The average fixed carbon content of the ore bodies is 16.32%.Graphites in the ore bodies mainly show flake textures with big flakes (>0.15 mm) of 37% and small to middle flakes (<0.15 mm) of 63%.The analysis on major and trace elements indicates that the protolith of the graphite-bearing schist has affinity to terrigenious argillaceous siltstone.Zircon SHRIMP U-Pb dating yields the metamorphic age of the graphite-bearing schist at (751.6±4.5) Ma.The δ13C of graphites averages on -24.17‰,which indicates the genesis of graphite in the deposit is mainly attributed to organic carbon.Therefore,we infer that the formation of the Pinghe deposit is closely linked to an organic origin and regional metamorphism.

Key words: Pinghe,Sichuan, scaly graphite deposit, geochemical feature, ore genesis

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