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%NaCl_(eqv).流体中液相离子成分主要为Ca^(2+)、Na^+、Mg^(2+)、SO_4^(2-)、Cl^-,气相成分主要为H_2O、N_2和CO_2及少量的CO、CH_4和H_2.流体的δDSMOW值范围为-60.4‰^-33.0‰,δ^(18)O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δ^(13)CPDB值范围为-4.89‰~0.57‰,δ^(18)OSMOW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.
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 Ca^2＋,Na^＋,Mg^2＋,SO4^2- and Cl^-,whereas the gaseous species consist of H2 O,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 δ^18O 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.Theδ13 CPDB and δ^18O SMOWof 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-andsulfate-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.
作者
李堃
赵少瑞
汤朝阳
段其发
李建威
Li Kun;Zhao Shaorui;Tang Zhaoyang;Duan Qifa;Li Jianwei(Faculty of Earth Resources,China University of Geosciences,Wuhan 430074,China;Wuhan Center of China Geological Survey,Wuhan 430205,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2018年第7期2449-2464,共16页
Earth Science
基金
中国地质调查局项目(Nos.1212011121100
1212010632005)
