【作者】 李志丹；

【导师】 薛春纪；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2011， 硕士

【摘要】 新疆南天山盆地沉积环境中铅锌资源丰富。典型铅锌矿床主要有两类:一类为晚古生代盆地内碳酸盐岩容矿铅锌矿床,以霍什布拉克,沙里塔什为代表;一类为中新生代盆地内碎屑岩容矿铅锌矿床,以乌拉根为代表。两类铅锌矿床具有重要的理论及经济意义。前人针对典型矿床已取得大量研究成果,但矿床成因类型仍争议颇多,严重制约了区域铅锌找矿。对典型矿床地质、地球化学及成因的认识亟待提高。晚古生代盆地内铅锌矿床以泥盆系碳酸盐岩为容矿岩石,矿体呈层状、似层状、板状,总体上严格层控,矿石矿物为闪锌矿和方铅矿,宏观及微观具有明显后生成矿特征,围岩蚀变较弱。中新生代盆地内乌拉根铅锌矿床以下白垩统砂砾岩及古新统白云岩为容矿主岩,矿体呈层状、似层状,矿石矿物为闪锌矿、方铅矿,以浸染状、脉状产出,围岩蚀变较弱。晚古生代盆地内霍什布拉克铅锌矿床单矿物稀土元素组成暗示成矿与重结晶泥晶灰岩相关,黄铁矿微量元素Co/Ni<1,暗示沉积成因,热液碳酸盐矿物C、H、O同位素指示成矿流体为盆地中的封存水,其中的碳主要来源于围岩碳酸盐岩。硫化物硫同位素组成(主要为16‰~ 24‰)反映硫来源于海相硫酸盐的热化学还原;铅同位素指示围岩提供了成矿物质。中新生代盆地内乌拉根矿床容矿地层地球化学特征指示容矿岩石为长石石英砂岩和岩屑石英砂岩,物源区构造背景为被动大陆边缘。硫化物硫同位素组成(-27.9‰~ 14.6‰)指示成矿所需的硫来自于相邻地层硫酸盐的生物动力分馏,铅同位素组成指示成矿物质来源于上地壳及造山带剥蚀区。结合当前铅锌成矿理论现状及典型矿床地质、地球化学研究,综合判定南天山晚古生代盆地内铅锌矿床成因类型为MVT;中新生代盆地内乌拉根铅锌矿床在与相近铅锌矿床成因类型对比后,判断其为少有的陆相沉积环境下的超大型砂岩型铅锌矿床。并认为乌拉根矿床的勘查突破开拓了中新生代陆相砂岩中寻找除金顶型矿床之外的超大型铅锌矿床的成功范例。更多还原

【Abstract】 The lead and zinc resources in sedimentary basin of southern Tianshan in Xinjiang are abundant. There are two typical deposits: one is hosted in carbonate rock of late Paleozoic basins, represented by Huoshibulake and Shalitashi ore; the other is hosted in clastic rock of Meso-cenozoic basins, represented by Wulagen deposit. These deposits are important for theoretical research and economic development. Although many researches have been carried out, there are still many controversies on deposit genisis. Therefore, the understanding of the deposit is in urgent need to be improved.The deposits in Paleozoic basins are hosted by the Devonian carbonate rock. The Pb-Zn ore body,with tabular shape as well as stratiform and stratoid, controlled by the strata. The ore minerals are mainly galena and sphalerite. The mineralization shows the evident epigenetic characteristics, with a weak wall-rock alteration. The Wulagen deposit in Paleozoic basin is hosted by the lower cretaceous sandy conglomerate and Paleocene dolomite. The orebody is stratiform and stratoid in shape and the ore minerals are mainly galena and sphalerite, occurring as disseminated and vein conditions. The wall-rock alteration is also weak.The REE compositions of monomineral in Huoshibulake indicated that the mineralization is related to recrystallization of micritic limestone. The Co/Ni<1 of pyrite indicates the genesis related to sedimentary basin fluid processes.δ¹³C_V-PDB,δD_V-SMOW andδ¹⁸O_V-SMOW shows the ore-forming fluids are likely to be the pent-up water in the basin, and the CO2 in the ore-forming fluids might be related to the strata of marine carbonate. Theδ³⁴S of the sulfide in ores mostly fall in the range from 16‰to 24‰, which indicates that the sulfur derives from the marine sulfate thermal chemical reduction. The Pb-isotopic compositions and related parameters suggest that the ore-forming material should be mainly from the upper crust supported by strata.The geochemistry of ore-bearing strata in Wulagen deposit in Meso-cenozoic basin show that the ore-hosted rock types are feldspar-quartz sandstone and lithic quartz sandstone and its provenance is passive continental margin. Theδ³⁴S of the sulfide in ore mostly fall in the range from -27.9‰to 14.6‰, which indicates that the sulfur derives from the marine sulfate bacterial reduction. The lead isotope composition suggests that the ore metals were derived from the erosion source of upper crust and orogenic belt.The lead-zinc metallegenic theory and the geological and geochemical charactersitcs of typical deposit lead to the conclusion that the ore type in Paleozoic basins is Mississippi valley type. After comparing with the lead-zinc ore type, we conclude that the Wulagen deposit in Meso-cenozoic basins is sandstone type in continental sedimentary environment and the exploration of Wulagen deposit is an successful example to find giant lead-zinc deposit in Meso-cenozoic sandstone of continental sedimentary environment.更多还原