投稿时间：2014-05-06
修订日期：2015-08-03
网络发布日期：2015-10-29
中文摘要:江西武山铜矿床是长江中下游多金属成矿带内重要的矽卡岩型矿床之一。文章对该矿床中的流体包裹体进行了详细研究,重点分析了成矿流体的演化过程及其成矿意义。根据野外地质产状和室内岩相学特征,将武山矽卡岩型铜矿床热液成矿过程分为气成-高温热液期和热液期,前者包括矽卡岩阶段和磁铁矿阶段,后者包括石英-硫化物阶段和碳酸盐阶段。其中,石英-硫化物阶段是该铜矿形成的主要阶段,可进一步细分为辉钼矿-石英和黄铁矿-黄铜矿-石英2个阶段。岩相学观察显示,包裹体类型有Ⅰ型含子矿物包裹体(L+V+S)、Ⅱ型气液两相包裹体(L+V)和Ⅲ型气相包裹体(Ⅴ)。气成-高温热液期的石榴子石中流体包裹体数量不多,但Ⅰ型、Ⅱ型和Ⅲ型包裹体都有;而热液期的石英与方解石中流体包裹体数量众多,以Ⅱ型包裹体为主。从早期矽卡岩阶段至碳酸盐阶段,成矿热液经历了从高温(378～518℃)、高盐度〔w(NaCleq)介于17.3%～45.1%〕向低温(113～250℃)、低盐度〔w(NaCleq)介于3.4%～11.9%〕的持续演化。热液演化过程中发生了流体沸腾作用和岩浆热液与大气降水的混合作用。其中,矽卡岩阶段的水-岩作用、沸腾作用与矽卡岩的形成密切相关,而成矿阶段的沸腾作用与混合作用可能是铜矿床形成的重要机制。H、O同位素研究表明,各成矿阶段的成矿流体以岩浆水为主,但随着成矿作用的进行,大气降水在成矿流体中的体积质量逐渐增大。
Abstract:The Wushan copper deposit is one of the most important skarn-type deposits along the Middle and Lower Yangtze River metallogenic belt. A detailed study of fluid inclusions in minerals of this deposit was carried out, with the emphasis placed on the evolution of ore-forming fluid and its ore-forming implications. Field investigation and petrographic observation indicate the existence of two periods of mineralization, i.e., pneumatolytic-hydrothermal mineralization period and hydrothermal mineralization period. The first period includes skarn and magnetite stages, whereas the second consists of quartz-sulfide and carbonate stages. As the main mineralization stage, the quartz-sulfide stage can be divided into two sub-stages, including quartz-molybdenite and quartz-pyrite- chalcopyrite respectively. Three types (Ⅰ, Ⅱ and Ⅲ) of fluid inclusions were observed in minerals of the deposit. Type Ⅰ consists of three-phase (vapor-liquid-solid) inclusions with daughter minerals, type Ⅱ of two-phase (vapor-liquid) inclusions, and type Ⅲ of one phase (vapor) inclusions. Fluid inclusions are rarely distributed in garnet formed during the pneumatolytic-hydrothermal epoch and include types Ⅰ, Ⅱ and Ⅲ. In contrast, fluid inclusions widely occur in quartz and calcite formed during the hydrothermal epoch and predominated by type Ⅱ. From the early skarn stage to the carbonate stage, temperature and salinity of ore-forming fluids continuously decreased from 378～518℃ to 113～250℃ and from 17.3%～45.1% to 3.4%～11.9%, respectively. Fluid boiling and mixing of magmatic hydrothermal fluid with meteoric water occurred during this evolution. The water-rock interaction and hydrothermal boiling in the skarn stage were related to the formation of skarn. The hydrothermal boiling and mixing in the quartz-sulfide stage might have been a significant mechanism for the formation of the copper deposit. Hydrogen and oxygen isotopic studies indicate that the ore-forming fluids were predominated by magmatic water during the formation of the deposit, with the gradual increasing of meteoric water.
keywords:geochemistry ore-forming fluids skarn thermometry of fluid inclusions H O isotope Wushan copper deposit
文章编号：
中图分类号：P618.41
文献标志码：
基金项目:本文研究得到中国地质调查局项目(编号:12120113069900)和国家自然科学基金项目(编号:40672045)联合资助
引用文本：
东前,杜杨松,苗文韬,曹毅,庞振山,曾锐,王剑波.2015.江西武山矽卡岩型铜矿床成矿流体演化及其成矿意义[J].矿床地质,34(5):929~947DONG Qian,DU YangSong,MIAO WenTao,CAO Yi,PANG ZhenShan,ZENG Rui,WANG JianBo.2015.Evolution of ore-forming fluids in Wushan skarn copper deposit, Jiangxi Province and its ore-forming implications[J].Mineral Deposits34(5):929~947
图/表
