| 湘西-黔东地区碳酸盐岩容矿铅锌矿床成矿模式 |
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| 引用本文： | 李堃,刘飞,赵武强,赵少瑞,汤朝阳,段其发,曹亮.湘西-黔东地区碳酸盐岩容矿铅锌矿床成矿模式[J].地球科学,2021,46(4):1151-1172. |
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| 作者姓名： | 李堃 刘飞 赵武强 赵少瑞 汤朝阳 段其发 曹亮 |
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| 作者单位： | 中国地质调查局武汉地质调查中心,湖北武汉 430205;中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉 430205;中国地质大学资源学院,湖北武汉 430074 |
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| 摘 要： | 湘西-黔东地区位于扬子陆块东南缘，在该地区碳酸盐岩地层中，目前已发现大、中、小型铅锌矿床及矿点200余处.为了解湘西-黔东地区铅锌矿床成矿作用过程，系统总结了区内主要铅锌矿床地质与地球化学特征，并对成矿机制进行探讨，建立成矿模式.区内铅锌矿床主要赋存于下寒武统碳酸盐岩中，分布明显受断裂及褶皱构造控制，矿体主要为层状、似层状或透镜状，矿物组成主要为闪锌矿、方铅矿、黄铁矿、方解石及少量萤石、重晶石和沥青，并伴随着广泛的以方解石化为主的热液蚀变.闪锌矿与方解石中的流体包裹体均一温度集中在120~200℃之间，盐度集中在8%~20%(NaCleqv)之间；成矿期方解石的δ13CPDB值范围为-4.89‰~1.50‰，δ18OSMOW值范围为13.37‰~25.09‰，略低于碳酸盐围岩；矿石硫化物δ34S值变化范围为22.3‰~36.1‰，以富含重硫为主；矿石硫化物铅同位素组成较为均一，变化范围较小，206Pb/204Pb在17.952~18.678之间，207Pb/204Pb在15.635~15.832之间，208Pb/204Pb在38.015~39.255之间.对地质和地球化学资料的综合分析表明，湘西-黔东地区铅锌矿床成矿流体为低温、中高盐度热卤水，主要来源于建造水和大气降水，成矿流体中的碳主要来源于碳酸盐围岩的溶解作用，硫来源于碳酸盐岩地层中硫酸盐热化学还原作用(TSR)，铅锌主要来源于下伏地层，成矿时代为晚志留世-早泥盆世，属于比较典型的密西西比河谷型(MVT)铅锌矿床.综合以上分析建立了该地区铅锌矿床有机质参与下的多源流体混合成矿模式.
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| 关 键 词： | MVT铅锌矿床 成矿流体 成矿物质来源 成矿模式 碳酸盐岩 湘西-黔东 矿床学 |
| 收稿时间： | 2020-06-02 |
Metallogenic Model of Carbonate-Hosted Pb-Zn Deposits in West Hunan and East Guizhou Provinces,South China |
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| Li Kun,Liu Fei,Zhao Wuqiang,Zhao Shaorui,Tang Zhaoyang,Duan Qifa,Cao Liang.Metallogenic Model of Carbonate-Hosted Pb-Zn Deposits in West Hunan and East Guizhou Provinces,South China[J].Earth Science-Journal of China University of Geosciences,2021,46(4):1151-1172. |
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| Authors: | Li Kun Liu Fei Zhao Wuqiang Zhao Shaorui Tang Zhaoyang Duan Qifa Cao Liang |
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| Abstract: | The West Hunan and East Guizhou district is located in the southeast margin of the Yangtze craton and developed with more than 200 Pb-Zn deposits/occurrences in carbonate rocks. In order to understand the metallogenic process of Pb-Zn deposits in West Hunan and East Guizhou district, in the paper it systematically summarizes the geological and geochemical characteristics of the typical Pb-Zn deposits, discusses the metallogenic mechanism, and establishes the metallogenic model. The Pb-Zn deposits are dominantly hosted in carbonate rocks of the Lower Cambrian, and the distribution is obviously controlled by fault and fold structure. The ore bodies are mainly stratiform, stratoid and lentoid. The minerals mainly consist of sphalerite, galena, pyrite and calcite, with less fluorite, barite, and bitumen. The Pb-Zn deposits are accompanied by extensive hydrothermal alteration dominated by calcilization. Fluid inclusions hosted in sphalerite and calcite have total homogenization temperatures concentrated of 120 to 200℃ and calculated salinities concentrated of 8% to 20% NaCleqv. Compared with the wall rocks, the hydrothermal calcite is characterized by relatively lower δ13CPDB value (range from -4.89‰ to 1.50‰) and significantly lower δ18OSMOW values (from 13.37‰ to 25.09‰). The sulfides from these Pb-Zn deposits yield narrow δ34S values (from 22.3‰ to 36.1‰). The lead isotope compositions of sulfides, with the 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb ratios ranging from 17.952 to 18.678, 15.635 to 15.832, 38.015 to 39.255, respectively, are relatively homogeneous. Integrating geological and geochemical data of the Pb-Zn deposits in West Hunan and East Guizhou district, it is suggested that low temperature and medium-high salinity ore-forming fluids were mostly derived from formation water with variable amounts of meteoric water; carbon in the ore-forming fluids was mainly sourced from carbonate wall rocks through water-rock reactions; sulfur was derived from the carbonate wall rocks by thermochemical sulfate reduction, and underlying strata supplied the metals for the Pb-Zn mineralization. The Pb-Zn deposits in West Hunan and East Guizhou district, formed in Late Silurian to Early Devonian, can be best classified as the MVT Pb-Zn deposit, and fluid mixing metallogenic model with the participation of organic matter was established in this district. |
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