江苏观山铜铅金矿床成矿流体地球化学和成因  

Geochemistry of ore-forming fluids and genesis of Guanshan Cu-Pb-Au polymetallic deposit in Jiangsu Province

作　　者：梁业恒[1] 孙晓明[1,2] 翟伟[1] 马春 吴志强 丁存根 王堂喜 李爱菊[2,3] 梁金龙[2] 

机构地区：[1]中山大学地球科学系,广东广州510275 [2]中山大学有色金属华东地勘局隐伏矿床勘查研究院,江苏南京210007 [3]华东有色地质矿产勘查开发院,江苏南京210007

出　　处：《矿床地质》2008年第5期605-612,共8页Mineral Deposits

基　　金：江苏省有色金属华东地质勘查局委托研究项目资助

摘　　要：观山铜铅金矿矿石中含有4种类型的流体包裹体:(Ⅰ)纯液相水溶液包裹体;(Ⅱ)富液相气液两相水溶液包裹体;(Ⅲ)富气相气液两相水溶液包裹体;(Ⅳ)纯气相包裹体。它们的气相分数变化较大,显示成矿过程中可能发生过沸腾作用。流体包裹体的显微测温结果显示,成矿流体的冰点温度为-0.3℃^-4.7℃,流体盐度w(NaCleq)变化范围为0.48%~7.39%,均一温度为133~304℃,对应流体密度为0.70~0.98g/cm3。同位素测定显示成矿流体的氢氧同位素组成分别为δD水=-81.0‰^-90.0‰,δ18O水=0.1‰~2.3‰,说明成矿流体主要为大气降水,但在矿体深部可能有少量岩浆水的加入。热液方解石碳同位素δ13C方解石=-1.2‰~2.9‰,显示其中的C主要来源于流体对流循环过程中对基底岩石中碳酸盐地层的溶解。综合成矿地质特征、成矿流体的证据与围岩蚀变类型,初步推断观山铜铅金矿为高硫型浅成低温热液金属矿床,沸腾作用可能是引起矿质发生沉淀富集成矿的重要因素之一。Four types of fluid inclusions were recognized in the Guanshan Cu-Pb-Au deposit, i.e., （Ⅰ） liquid aqueous inclusions, （Ⅱ） liquid-rich two-phase fluid inclusions, （Ⅲ） gas-rich two-phase inclusions, and （Ⅳ） pure gaseous inclusions. Different types of inclusions with remarkably varied vapor/liquid ratios exist together, implying that boiling might have occurred during mineralization. Microthermornetric measurement of the fluid in- clusions show that the ice melting temperatures range from - 0. 3℃ to - 4. 7℃, and the corresponding salinities vary from 0.48 wt % to 7.39 wt% NaCleq. The homogenization temperatures range from 133℃to 304℃, with densities from 0.70 to 0.98 g/cm^3. Isotopic analyses show that δDH2O and δ^18OH2O values of the ore-forming fluids are -81.0‰ to - 90.0‰ and 0.1‰ to 2.3‰, respectively, indicating that the ore-forming fluids are composed mainly of meteoric water, probably with the involvement of magmatie fluids. Carbon isotopic composition of hydrothermal calcites form the ore veins （δ^13Ccalcite） are - 1.2‰-2.9‰, suggesting that carbon in the ore-forming fluids was derived from carbonate sediments in the basement rocks. Geological characteristics, ore- forming fluid geochemistry and alteration assemblage suggest that the Guanshan Cu-Pb-Au deposit might be a high sulfidation type epithermal polyrnetallic deposit, and boiling seems likely to be the main factor for the deposition of ore solutions.

关 键 词：地球化学 流体包裹体 氢氧同位素组成 浅成低温热液矿床 观山铜铅金矿 

分 类 号：P618.51[天文地球—矿床学]