新疆乌恰县萨热克铜矿床地质特征及硫、铅同位素地球化学

摘要

萨热克铜矿是塔里木盆地西北缘中新生界沉积盆地内的大型矿床.矿床定位于托云中生代拉分盆地西缘与东阿赖海西晚期深海盆之间的萨热克巴依中生代断陷盆地内,矿体呈层状、透镜状分布于上侏罗统库孜贡苏组上段(J3k2)灰绿色砾岩层位中,矿石矿物主要为辉铜矿、孔雀石,围岩蚀变较弱.矿石中辉铜矿δ34S=-24.0‰～- 19.0‰,指示硫来自地层中大量硫酸盐的生物还原作用,辉铜矿206Pb/204 Pb比值范围为18.475～18.642,207Pb/204 Pb为15.606～15.676,208Pb/204Pb为38.585 ～38.795,指示成矿金属来自于上地壳和造山带剥蚀区.结合矿床地质及地球化学研究,判断萨热克铜矿是与盆地流体活动相关的砾岩型铜矿.%Sareke copper deposit in Meso-Cenozoic sedimentary basins of northwestern margin of Tarim Basin is a large-scale deposit. The tectonic location of the deposit is located in the Sarekebayi Mesozoic fault basin, which is seated between the western margin of Tuoyun Meso-Cenozoic pull-apart basin and Late Hercynian deep ocean basin in east Alai. The orebodies, with the layered and lens-like shape, occurred in the gray green conglomerate belonging to the second lithologic section of Upper Jurassic Kuzigongsu Formation. The main metallic minerals are chalcoeite and malachite with weak country rock alteration. S S of chalcocite is in the range of -24. 0‰~ -19. 0‰, indicating that the sulfur are mainly derived from biological reduction of the strata sul-fate. The ratio of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb are 18.475 ~ 18.642, 15.606 ~ 15.676, and 38. 585 ~ 38. 795, respectively, which illustrate that the ore-forming matters are mainly from upper crust and orogenic erosion zone. Geological characteristics and geochemistry of the copper deposit lead to the conclusion that Sareke copper deposit is a basin fluid-related conglomerate type deposit.