中文摘要：

蟒硐铅锌矿床位于黔西北铅锌成矿区垭都-蟒硐构造成矿亚带南东部,紧邻筲箕湾铅锌矿床,为一小型矿床。对该矿床主要原生矿体主成矿期块状硫化物矿石中的黄铁矿、闪锌矿和方铅矿进行了S、Pb同位素组成分析。结果表明该矿床S同位素组成变化不大,介于＋10.7‰~＋13.7‰（均值＋12.2‰,n=12）,与筲箕湾矿床δ34S CDT值相近（＋8.4‰~＋11.6‰,均值10.5‰,n=11）,不同于δ34SCDT值在0±3‰的幔源硫,而与地层蒸发岩中所含的石膏（＋15‰）和重晶石（＋22‰~＋28‰）以及泥盆纪至三叠纪海水（＋20‰~＋35‰）的S同位素组成相近。因此,推测成矿流体中的S是地层膏盐层中海相蒸发硫酸盐热化学还原的产物。蟒硐矿床Pb同位素组成变化较小,其206Pb/204Pb为18.582~18.668（均值18.635,n=6）,207Pb/204Pb为15.706~15.811（均值15.739,n=6）和208Pb/204Pb为39.075~39.341（均值39.176,n=6）。在207Pb/204Pb-206Pb/204Pb图上位于上地壳铅平均演化线之上,主要与上泥盆统至下二叠统沉积岩投影区域重叠,部分与基底岩石投影区域重叠,与峨眉山玄武岩投影区域明显不同。因此,蟒硐矿床成矿流体中的金属主要来自赋矿沉积岩,但不能排除基底岩石的贡献。综合分析认为,蟒硐铅锌矿床成矿流体和物质均主要来自赋矿地层沉积岩,部分来自基底岩石,峨眉山玄武岩没有明显贡献,矿床成因属于与盆地卤水有关的后生热液矿床。

英文摘要：

Mangdong deposit, a small scale Pb-Zn deposit near the medium scale Shaojiwan Pb-Zn deposit, is located in the southeast of Yadu-Mangdong tectonic-metallogenic belt, northwestern Guizhou Pb-Zn metallogenic district, China. The S and Pb isotopes of the main ore-forming stage sulfide separates from the main ore body in this deposit were analyzed in this paper. Results show that S isotopic compositions of sulfide separates range from ＋10.7‰ to ＋13.7‰（average ＋12.2‰, n=12）, which is similar to those of sulfide separates from Shaojiwan deposit（＋8.4‰~＋11.6‰, average 10.5‰, n=11）, but is different from those of mantle-derived S（0±3‰）. All the δ34S CDT values of sulfide separates from Mangdong and Shaojiwan deposits are similar to those of gypsum（＋15‰） and barite-bearing（＋22‰~＋28‰） evaporites and Devonian to Triassic seawater（＋20‰~＋35‰）. Therefore, the reduced S in the ore-forming fluids was the produce of marine sulfate by thermal chemical sulfate reduction. The 206Pb/204 Pb, 207Pb/204 Pb and 208Pb/204 Pb values range from 18.582 to 18.668（average 18.635, n=6）, 15.706 to 15.811（average 15.739, n=6） and 39.075 to 39.341（average 39.176, n=6）, respectively. All the Pb isotopic data plot in the field above the upper crust Pb average evolution line, overlap with that of the Upper Devonian to Lower Permian sedimentary rocks and Proterozoic basement rocks, but are different from that of Emeishan basalts. Therefore, we propose that the ore-forming metals were mainly derived from the carbonate host rocks, but we can＇t rule out the contribution of the basement rocks. Geology and isotope geochemistry information suggest that the ore-forming fluids and metals were mainly sourced from the carbonate host rocks, parts originated from the basements, but Emeishan basalts don＇t have obvious contribution, and the ore genesis of Mangdong deposit belongs to epigenetic hydrothermal deposit related to basin brines.