康滇地轴东缘铅锌矿床铅硫同位素地球化学研究

康滇地轴东缘不同时代碳酸盐地层中铅锌矿床的铅同位素研究表明 ,其2 0 7Pb/2 0 4 Pb与2 0 6 Pb/ 2 0 4 Pb呈良好线性关系 ,2 0 7Pb/ 2 0 6 Pb和2 0 8Pb/ 2 0 6 Pb为一常数。结合对本区矿床的稀土元素及成矿流体地球化学的研究 ,判定不同层位铅锌矿床是在同一个成矿体系同时形成的 ,一次成矿 ,其成矿年龄为 2 4 5Ma(峨眉运动 ) ;同时说明不同矿床成矿金属有相同的来源 ,主要来自上地幔。成矿硫以来自地层中的硫酸盐还原硫为主 ,幔源硫次之。本区铅锌矿床的成矿作用与峨眉山玄武岩的喷流关系密切 ,这是与著名的MVT型铅锌矿床的显著区别。

LEAD-SULFUR ISOTOPE STUDY OF CARBONATE-HOSTED LEAD-ZINC DEPOSITS AT THE EASTERN MARGIN OF THE KANGDIAN AXIS

Lead isotope data for carbonate\|hosted lead\|zinc deposits in the strata of various ages at the eastern margin of the Kangdian axis show that \{\}\+\{207\}Pb/\{\}\+\{204\}Pb versus \{\}\+\{206\}Pb/\{\}\+\{204\}Pb ratio is of good linear correlation, and \{\}\+\{207\}Pb/\{\}\+\{206\}Pb, \{\}\+\{208\}Pb/\{\}\+\{206\}Pb and \{\}\+\{208\}Pb/\{\}\+\{207\}Pb ratios are constant, respectively. REE and ore\|forming fluid geochemistry demonstrates that the lead\|zinc deposits in this district were formed at the same time in the same ore\|forming system with a mineralization age of 245Ma (Emei movement). Ore metals were derived mainly from the upper mantle and ore sulfur was derived mainly from sulfate in the strata with mantle\|derived sulfur coming next. Ore\|forming process in the district has important relationship with the eruption of the Emei basalt magma. This feature is quite different from the famous Mississippi Valley\|type deposits.