【摘要】 长江中下游地区是中国重要的铜、金、硫产地,区内分布着一系列喷流沉积及喷流沉积热液叠加改造型层状铜金矿床。本文以冬瓜山层状铜矿床为例,通过热液流体和矿石同位素地球化学研究,探讨层状铜矿床的成矿机制,重点分析了成矿物质的来源。冬瓜山铜矿床热液流体氢、氧、碳和锶同位素分析表明,成矿热液流体主要来自岩浆,混有少量大气降水;CO2可能主要来自被岩浆同化的原始地层中海相沉积碳酸盐;ISr具有地壳物质来源的特征。各种类型矿石的硫、铅同位素研究显示,硫具有海底喷流沉积和后期岩浆热液叠加作用的特征,铅则以上地壳铅为主,混有少量的地幔铅。上述同位素地球化学特征表明冬瓜山层状铜矿床是在原始沉积基础上,经燕山期岩浆热液叠加成矿作用所形成。更多还原

【Abstract】 The region of the middle—lower reach of the Yangtze River is an important mining district of copper, gold and other elements where a series of sedimentary-hydrothermal diplogenetic stratabound copper mineral deposits. Taking the Dongguashan deposit as a study case, this study invesitigates the mineralizing material origin and metallogenic mechanism of these sedimentary-hydrothermal diplogenetic stratabound copper deposits based on the analysis of isotope geochemistry. The hydrogen and oxygen isotope composition of the fluid inclusions in vein quartz of different stages shows that the ore-forming fluids are mainly originated from magmatic fluid with a minor mixture of meteoric water. δ13C of the inclusions shows that CO2 was derived from the carbonate assimilated by magma. ISr proves that ore-forming materials mainly originated from the crust, and δ34S data indicates that the sulfur is from submarine exhalation sedimentation and exhibits characteristics of hydrothermal superimposing. In addition, the similarity in lead isotopic compositions of different ores indicates that the ore-forming material was mainly derived from the upper crust, and partly originated from the magma. By integrating the isotopic dating data and the geological setting, it is proposed that the mineralizing processes of Dongguashan copper deposit could be divided into two stages. In the first stage, stratiform sedimentary deposit or protore layer formed in later Devonian to later Carboniferous period. In the second stage, the pre-existing protore was diplogeneticaly alternated by the hydrothermal fluids mainly derived from the Yanshanian magmatic activities.更多还原