| 湘西北花垣矿集区铅锌矿床成矿流体来源及矿床成因 |
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| 引用本文： | 李堃,赵少瑞,汤朝阳,段其发,李建威.湘西北花垣矿集区铅锌矿床成矿流体来源及矿床成因[J].地球科学,2018,43(7):2449-2464. |
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| 作者姓名： | 李堃 赵少瑞 汤朝阳 段其发 李建威 |
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| 作者单位： | 1.中国地质大学资源学院, 湖北武汉 430074 |
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| 基金项目： | 中国地质调查局项目1212010632005中国地质调查局项目1212011121100 |
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| 摘 要： | 湘西北花垣矿集区位于扬子地台东南缘，是湘西-鄂西成矿带上最典型的超大型铅锌矿床所在地.通过对花垣矿集区典型铅锌矿床流体包裹体显微测温、成分分析及C、H、O同位素研究，结果表明，该区铅锌矿床闪锌矿与方解石中流体包裹体的均一温度范围集中在120~200℃，盐度范围集中在8%~20% NaCleqv.流体中液相离子成分主要为Ca2+、Na+、Mg2+、SO42-、Cl-，气相成分主要为H2O、N2和CO2及少量的CO、CH4和H2.流体的δDSMOW值范围为-60.4‰~-33.0‰，δ18O流体值范围为3.8‰~9.2‰.以上流体包裹体和稳定同位素分析结果表明，花垣矿集区铅锌矿床的成矿流体具有热卤水的性质，主要来源于建造水和大气降水.成矿期方解石的δ13CPDB值范围为-4.89‰~0.57‰，δ18OSMOW值范围为13.37‰~21.73‰，略低于碳酸盐围岩，说明成矿流体中的碳主要来源于碳酸盐围岩的溶解作用.矿石沉淀机制可能为两种流体的混合，即来自深部的富含金属物质的热卤水与富含有机质和硫酸盐的建造水及下渗大气降水的混合导致了铅锌矿石的沉淀.对地质和地球化学资料的综合结果表明，花垣矿集区铅锌矿床属于密西西比河谷型（MVT）铅锌矿床.
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| 关 键 词： | 流体包裹体 碳、氢、氧同位素 流体来源 矿床成因 花垣矿集区 MVT型铅锌矿床 化学分析 |
| 收稿时间： | 2018-02-12 |
Fluid Sources and Ore Genesis of the Pb-Zn Deposits of Huayuan Ore-Concentrated District,Northwest Hunan Province,China |
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| Abstract: | The Pb-Zn deposits of Huayuan ore-concentrated district in northwest Hunan Province are located on the southeastern margin of the Yangtze Craton. It has been one of the most important giant Pb-Zn deposits in Xiangxi-Exi metallogenic belt. Through the microthermometric and component analysis of the fluid inclusion, and the C, H, O isotope study of the Pb-Zn deposits in Huayuan ore-concentrated district, the results show that 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. Compositionally, the fluid inclusions are dominated by Ca2+, Na+, Mg2+, SO42- and Cl-, whereas the gaseous species consist of H2O, N2, CO2 with a small amount of CO, CH4, H2. Based on hydrogen isotopes of fluid inclusion waters and oxygen isotopic compositions of calcite, the ore fluids have δDSMOW and δ18O fluid of -60.4‰ to -33.0‰ and 3.8‰ to 9.2‰, respectively. Thus, the isotope data suggest that the ore-forming fluids were mostly derived from formation water, with variable amounts of meteoric water. The δ13CPDB and δ18OSMOW of calcite range from -4.89‰ to 0.57‰ and from 13.37‰ to 21.73‰, respectively, indicating that carbon in the ore-forming fluids was mainly sourced from carbonate wall rocks through water-rock reactions. Precipitation of the sulfide ores was attributed to mixing of two end-member fluids, i.e., metalliferous fluid and organic-and sulfate-rich fluids. Integration of geological and geochemical data suggest that the Pb-Zn deposits of Huayuan ore-concentrated district can be best classified as the MVT Pb-Zn deposit. |
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