陕西勉县庙坪石墨矿床地球化学特征及成矿机制研究  

Geochemical characteristics and genetic mechanism of the Miaoping graphite deposit in the Mianxian County of Shaanxi Province

作　　者：汤贺军 张宝林[3] 吴珍汉[1,2] 孟贵祥 张国梁[3] 张文斌 TANG Hejun;ZHANG Baolin;WU Zhenhan;MENG Guixiang;ZHANG Guoliang;ZHANG Wenbin(Chinese Academy of Geological Sciences,Beijing 100037,China;China Deep Exploration Center,China Geological Survey&Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;No.214 Team,Shaanxi Nuclear Industry Geological Bureau,Hanzhong,Shaanxi 723200,China)

机构地区：[1]中国地质科学院,北京100037 [2]中国地质调查局-中国地质科学院地球深部探测中心,北京100037 [3]中国科学院地质与地球物理研究所,北京100029 [4]陕西省核工业地质局二一四大队,陕西汉中723200

出　　处：《地质学报》2021年第8期2509-2520,共12页Acta Geologica Sinica

基　　金：国家重点研发计划专项课题(编号2018YFC0604002);中国地质调查局项目(编号DD20190071、DD20190012);中国地质科学院基本科研业务费项目(编号JKY201908-02)联合资助的成果。

摘　　要：新发现的勉县庙坪石墨矿床位于南秦岭勉略缝合带,工业类型为晶质鳞片状石墨矿石。本文对该矿床进行地球化学特征研究,并探讨其成因机制。研究结果表明,含矿岩石黑云母变粒岩Al2O3含量为7.32%~15.01%、TFeO为2.28%~8.68%、Na_(2)O为0.17%~3.38%、K_(2)O为1.15%~3.42%、TiO_(2)为0.50%~0.80%,稀土元素总量为106.38×10^(-6)~236.37×10^(-6);黑云母变粒岩具有明显的Eu、Sr负异常,U、Cs、Pb的正异常,Ce异常不明显。通过对本区变质原岩恢复、沉积环境及原岩物质来源分析可知,矿区变质岩原岩应为沉积岩,具有泥质砂岩、粉砂岩的特征,变质岩系原岩主要形成于缺氧还原的海洋沉积环境。碳同位素分析显示,矿石中石墨的δ13C为-23.6‰~-21.7‰,大理岩的δ13C为-7.1‰~3.3‰,石墨中的碳质来源主要为生物有机质,而大理岩的碳质来源为无机碳。本区经区域变质作用,使含碳质岩石富化成矿,矿床成因应属沉积变质型矿床。The newly discovered graphite ore deposit in the Miaoping Mianxian County is located in the southern Qinling Mian-Lüe suture zone.The industrial type is crystalline flake graphite ore.This paper systematically analyzes the geochemical characteristics of samples and discusses the metallogenic conditions and genesis of the graphite ore deposit.The results show that the content of Al2O3(7.32%~15.01%),TFeO(2.28%~8.68%),Na_(2)O(0.17%~3.38%),K_(2)O(1.15%~3.42%)and TiO_(2)(0.50%~0.80%)in biotite granulite are relatively high.TheΣREE of biotite-granulite is 106.38×10^(-6)~236.37×10^(-6).δEu and Sr of biotite granulite show the negative anomaly,U,Cs,Pb show positive anomaly,butδCe anomaly is not obvious.The protolith of metamorphic rock in the mining area should be sedimentary rock with the characteristics of argillaceous sandstone and siltstone,which was mainly formed in the marine sedimentary environment of anoxic reduction.C isotope analysis shows that theδ13C of graphite in ore is-23.6‰~-21.7‰,and that of marble is-7.1‰~3.3‰indicating that the graphite carbon is derived from biological organic matter,and carbon of marble from inorganic carbonate mass.Regional metamorphism helped to transform the rocks to ore zones.The genetic type of the deposit belongs to sedimentary metamorphic deposits.

关 键 词：勉县庙坪 石墨矿 地球化学 碳同位素 成因机制 

分 类 号：P619.252[天文地球—矿床学]