投稿时间：2020-08-04
修订日期：2021-04-18
网络发布日期：2021-07-12
中文摘要:湖南康家湾铅锌金银矿床位于南岭成矿带北部中段，是水口山矿田内发现较晚的大型隐伏矿床。该矿床的矿物组合及矿化特征复杂，前人对其成矿流体特征及成因类型存在不同认识。文章通过野外地质调查和矿物矿相学研究发现该矿床的热液成矿阶段较多，方铅矿主要形成于早期闪锌矿与晚期闪锌矿之间，而金和银的成矿阶段分别与早期闪锌矿和方铅矿趋于一致。电子探针成分分析结果显示早期闪锌矿的含铁量（x（FeS）=9.0%~19.1%）明显高于晚期闪锌矿的（x（FeS）=0.1%~4.0%），与黄铁矿和磁黄铁矿共生的闪锌矿含铁量估算得到的成矿压力值范围为100~146 MPa。早期闪锌矿中流体包裹体的均一温度范围为190~370℃，盐度w（NaCleq）范围为5%~11%，均明显高于晚期闪锌矿。基于矿物组合特征的热力学模拟计算显示早期的成矿流体具有低氧逸度和中酸性的特征，为金的沉淀提供了有利条件。总体上，康家湾矿床的成矿流体演化具有温度和压力由高变低、氧逸度由低变高、pH值由低变高但均为中酸性，金属元素含量由多变少的变化趋势。以上成矿流体特征暗示康家湾矿床具矽卡岩型矿化特征，指示深部存在找矿潜力。
Abstract:The Kangjiawan Pb-Zn-Au-Ag deposit, located in the middle segment of the northern Nanling metallogenic belt, is a buried large-sized deposit found relatively late in the Shuikoushan orefield. Due to complicated mineralization and diverse mineral assemblages, characteristics of ore-forming fluids and types of ore genesis are still in debate. In this study, field work and ore microscopic investigation revealed multiple metallogenetic stages in the deposit. The main stage of galena is between the earlier sphalerite and the later sphalerite, and the stage of gold and silver mineralization is associated with the earlier sphalerite and galena, respectively. EPMA analysis results show the higher FeS content (x(FeS)=9.0%~19.1%) in the earlier sphalerite but the lower FeS content (x(FeS)= 0.1%~4.0%) in the later sphalerite. The FeS content of the earlier sphalerite associated with pyrite and pyrrhotite indicates that the ore-forming pressure is from 100 MPa to 146 MPa. Homogenization temperatures (190~ 370℃) and salinities (w(NaCleq) 5%~11%) of fluid inclusions in the earlier sphalerite are clearly higher than those of the later sphalerite. Thermodynamic calculation based on mineral associations shows a lower fO2 and intermediate-acid conditions in the earlier ore-forming fluid that may be favorable for the precipitation of gold. Therefore, during the evolution of ore-forming fluids, temperature, pressure and content of metal elements of the fluids might be changed from high to low, whereas fO2 and pH might be increased. These results may indicate that the mineralization of the Kangjiawan deposit in the earlier metallogenetic stage is characterized by the skarn type.
keywords:geochemistry mineralogy characteristics of ore-forming fluid thermodynamic calculation PbZn-Au-Ag deposit Kangjiawan
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基金项目:本文得到国家自然科学基金（编号：41702077）和中央高校基本科研业务费专项资金（编号：2682016CX090）联合资助
引用文本：
梁翼,钟建胜,JOUKOU Suguru,裴秋明,HOSHINO Kenichi.2021.湖南康家湾矿床的成矿流体特征:基于矿物学、流体包裹体及热力学计算的制约[J].矿床地质,40(3):475~490LIANG Yi,ZHONG JianSheng,JOUKOU Suguru,PEI QiuMing,HOSHINO Kenichi.2021.Characteristics of ore-forming fluids of Kangjiawan deposit in Hunan Province: Constraints from mineralogy, fluid inclusions thermodynamic calculation[J].Mineral Deposits40(3):475~490
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