鄂西黄陵背斜地区石墨矿床含矿岩石的地球化学特征及物源分析  

Geochemical characteristics and provenance analysis of ore-bearing rock in the graphite deposit of Huangling anticline,Western Hubei

作　　者：郭威 陈梦杰 闫斌[2,3] 杨宏伟 曾凯 万传辉 刘林 斯小华 王腾 范玖琳 秦元奎 刘海 GUO Wei;CHEN Meng-jie;YAN Bin;YANG Hong-wei;ZENG Kai;WAN Chuan-hui;LIU Lin;SI Xiao-hua;WANG Teng;FAN Jiu-lin;QIN Yuan-kui;LIU Hai(Hubei Institute of Metallurgical Geology(Zhongnan Institute of Metallurgical Geology),Yichang 443000,China;Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Key Laboratory of Isotope Geology of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]湖北冶金地质研究所(中南冶金地质研究所),湖北宜昌443000 [2]中国地质科学院地质研究所自然资源部深地动力学重点实验室,北京100037 [3]中国地质科学院地质研究所自然资源部同位素地质重点实验室,北京100037

出　　处：《桂林理工大学学报》2020年第3期457-469,共13页Journal of Guilin University of Technology

基　　金：湖北省自然科学基金项目(2019CFB751,2016CFB637)。

摘　　要：鄂西黄陵背斜地区石墨成矿地质条件优越,是我国晶质石墨矿的重要产区。为了厘清成矿物质来源,认识石墨矿的成矿规律,对该地区石墨矿的含矿样品进行了岩相学、元素和碳同位素地球化学分析。石墨片岩的主要成分是SiO2(46.51%~67.56%)、Al2O3(11.41%~15.24%)、固定碳(1.86%~17.85%);大理岩及钙硅酸盐岩主要成分为CaO(27.7%~32.9%)、MgO(18.40%~19.95%)和SiO2(4.22%~20.50%)。石墨片岩样品中ΣREE在(114.78~241.85)×10-6,LREE/HREE值为8.65~22.51,(La/Yb)N值为11.78~71.29;δEu为0.36~0.87,δCe为0.38~0.99;大理岩及钙硅酸盐岩ΣREE在(14.42~235.30)×10-6,LREE/HREE值为5.24~11.55,(La/Yb)N值为6.02~14.89,δEu为0.63~0.94,δCe为0.91~0.99。含矿样品稀土元素整体呈现轻稀土元素富集,轻、重稀土元素分异较强烈,具有轻微的铈负异常和明显的铕负异常。这些地球化学特征表明,含矿岩石的原岩是一套由发育在较稳定陆棚环境中的碎屑岩、泥质岩及碳酸盐岩所组成的沉积建造,含矿岩石的主要物源是野马洞岩组。石墨矿石样品δ13C值为-9.69‰^-25.35‰,说明碳主要来源于同源沉积的有机物。在黄陵背斜地区,野马洞岩组的分布区域是石墨矿潜在的有利成矿位置。The Huangling anticline area with superior geological conditions for graphite mineralizations,is an important producing area of crystalline graphite in China.In order to clarify the ore-forming material sources,and to understand the ore-forming laws graphite deposits,the ore-bearing samples are studied by electron microscope,elements and carbon isotope geochemistry analysis.The main compositions of graphite schist are SiO2(46.51%-67.56%),Al2O3(11.41%-15.24%),fixed carbon(1.86%-17.85%).The main components of marble and calcium silicate rock are CaO(27.7%-32.9%),MgO(18.40%-19.95%)and SiO2(4.22%-20.50%).The total amount of rare earth(ΣREE)in the graphite schist sample is(114.78-241.85)×10-6,LREE/HREE value is 8.65-22.51,(La/Yb)N value is 11.78-71.29;δEu is 0.36-0.87,δCe is 0.38-0.99.The marble and calcium silicate rockΣREE is(14.42-235.30)×10-6,LREE/HREE value is 5.24-11.55,(La/Yb)N value is 6.02-14.89,δEu is 0.63-0.94,δCe is 0.91-0.99.REE distribution patterns of ore-bearing samples are found enriched with LREE and flatted HREE,with the strong differentiation of LREE and HREE,the slight Ce negative anomalies and obvious Eu negative anomalies.These geochemical characteristics indicate that the protoliths of ore-bearing rock are a set of sedimentary structures composed of clastic rock.Argillaceous rock and carbonate rock developed in a relatively stable shelf environment.The main source of ore-bearing rock is the Yemadong Formation.Theδ13C ratios of graphite samples,ranging from-9.69‰to-25.35‰,suggest that the carbon source of graphite mineralization comes originally from the organic sediments.In Huangling anticline area,the distribution area of the Yemadong Formation is a potential favorable metallogenic location for graphite deposits.

关 键 词：石墨矿 地球化学 成矿物质来源 黄陵背斜地区 鄂西 

分 类 号：P588.124[天文地球—岩石学]