【作者】 张晗；

【导师】 李碧乐；

【作者基本信息】 吉林大学 ， 矿物学、岩石学、矿床学， 2009， 硕士

【摘要】 阿克塔什、萨落依VMS矿床位于西昆仑造山带北带,萨落依铜矿产于下石炭统乌鲁阿特组中-基性火山岩岩层中,阿克塔什VMS产于上石炭统克孜里奇曼组酸性火山岩中,它们属于VMS类型矿床,结合前人研究成果,研究认为这两个矿床所在的昆盖山北坡石炭纪火山岩生成环境为洋壳,下石炭统萨落依地区玄武岩即表现出MORB特征,又在一些方面显示出岛弧火山岩的特征;而上石炭统阿克塔什地区亏损不相容元素的中酸性火山岩很可能是亏损不相容元素的源区部分熔融形成的,昆盖山北坡石炭纪火山岩很可能是昆北带石炭纪弧后盆地发展到不同阶段的产物,其性质和昆北带的蛇绿岩非常类似,很可能为昆北蛇绿岩带中石炭纪蛇绿岩的北沿部分。通过岩矿鉴定、岩石微量元素分析、流体包裹体测试等方法手段,对矿石矿物特征、成矿地质、物理化学条件等进行了分析研究,探讨了矿床地质特征、成矿物质来源、成矿流体条件以及成矿机制。研究认为阿克塔什-萨落依的成矿流体主体为海水,在火山活动提供的热场驱动下,循环水可以从围岩中提取成矿物质,载矿流体喷入海水环境后,由于物化条件的变化,导致混合流体在适当的位置卸载成矿物质,形成层状矿体和热水沉积岩,另一部分的矿化发生在通道相中,形成脉状矿化。另外,一些间接的证据表明,Cu也有可能来源于岩体并可能有岩浆流体带入最终的成矿流体系统。更多还原

【Abstract】 Western Kunlun Orogenic Belt locates in the northwestern part of China.As a result of natural conditions in the West Kunlun, the relative lack of basic geological data, Also Aktash and Saluoyi (SLY) deposits are relative lack of research, and make the ore genesis of these two deposits there is a dispute,besides the unclear of deposits geological information, the key problems led to this situation is the lack of study of tecotonic elvolution of Kungaishan mountain area,.According to the main stratigraphy and regional structure of the West Kunlun, it is usually divided into three zone,namely the North Zone,the Middle Zone and the South Zone. There are a series of ophiolites locates in the North Zone, from west to east, distribute the Oytag, the Kudi and the Subasi ophiolite respectively. The Lower Carboniferous volcanic rocks of the Wuluate formation is mainly composed of tholeiites which associated with intermediate volcanic rocks are spilite - keratophyre series, The Keziliqima formation which host Akatsh VMS is composed of a group Upper Carboniferous volcanic rocks (spilite - keratophyre - quartz keratophyre) and marine sedimentary rocks.According to geochemisitry study of Lower Carboniferous basalt of this aera ,the mafic volcano of Saluoyi shown geochemistry of MORB+OIB, Chondrite-normalized rare earth-element patterns for the tholeiite associations from the SLY is similar to MORB’s, and the distribution of trace elements show the characteristics of island arc basalt. Nb*2 vs. Zr vs.4-Y discrimination diagram show that it formed in the E-MORB or N-MORB background, TiO2 vs. Zr show that it formed in the MORB background, Hf/3 vs.Th vs.Ta discrimination diagram show it formed in MORB background too, however, crystallization differentiation of homologous basaltic andesite and andesite basalt is in the region of island-arc environment. Geochemical natures of those are similar to the tholeiite of the Oytag-Kudi-Subasi ophiolite. Therefore the Kungaishan volcanic rocks is likely to a part of ophiolite of the North Zone. The Upper Carboniferous volcanic rocks are characterized by its incompatible elements are depleted, It can be derived from a source region which is relative loss the incompatible elements, the geochemical characteristics of volcanic rocks indicate that this is the generation of oceanic-crust environment. Geochemistry of the basalt of SLY have complex geochemical features of mixed MORB and island arc basalt features , It is worth mentioning that the basalt of SLY show accordance with the performance of the E-MORB + IAT characteristic, Shichito modern back-arc basin that show the feature similar to that (Yasuo Ikeda and Makoto Yuasa, 1989), suggesting that the Lower Carboniferous and Upper Carboniferous volcanic rocks of the Kungaishan mountain is likely to be the product of back-arc basin in different stages.SLY VMS hosted in the Lower Carboniferous volcanic rocks of Wuluate formation, mineralization often associated with the fractionated surrounding rock,ore types of No.ⅠandⅡore boby are mainly briquette-like type , disseminated type or stockwork type, Alteration of wall rocks associated with mineralization are chloritization, silicification, epidotization, carbonation. Ore-types of No.Ⅲore body of SLY is massive type, banded type . Ore body is composed of two parts, the upper exhalative rock, the thickness of about 3m; the lower ore body is composed of the massive, banded type ore, mainly by chalcopyrite and associated with a small amount of pyrite, sphalerite, magnetite etc., the thickness of about 2m. According to mineral assemblage, the combination of primary sulfide ores can be divided into three main types: pyrite ore, pyrite - chalcopyrite type and pyrite-chalcopyrite-sphalerite ore. According to structure of ore, it can be divided into three main types: massive, banded ore and disseminated- stockwork type.Aktash VMS hosted in the acidic end-member of the Upper Carboniferous volcanic rocks, which is depleted LILS and HFSE. Ore body is layered or plate-like between the tuff and the rhyolite which Metamorphosed to quartz schist or quartz-mica schist already. Ore body is composed of two parts, the upper massive, banded ore, and the lower disseminated- stockwork ore.Metal minerals mainly pyrite, a small amount of chalcopyrite, sphalerite and trace tennantite, such as the composition of the main gangue mineral is quartz, a small amount of sericite, muscovite and calcite, etc..The fluid in the fluid inclusions of epidote-quartz rock of SLY can be divided into two groups: a group of about 4% salinity, the other group without salinity (salinity may too low to detect), two types of packages with the similar gas-liquid ratio, and estimated the ore-forming temperature range of 167.4℃-217℃by limit the pressure of fluid.Comparison of modern seaftoor polymetallic massive sulfides hydrothermal system, combined with the ore-forming geological characteristics and the tectonic setting of SLY and Aktash VMS deposits, SLY is the Cyprus-type VMS; Aktash is similar to the product of the modern LAU back-arc basin "chimneys" ,and its geological features are similar to the Noranda-type VMS except ore-forming age. The geological features of Aktshi and SLY VMS show that the Pb, Zn are most likely to come from the surrounding rock.Some indirect evidence suggesting that Cu may also be derived from igneous rock by magmatic fluid and added into the hydrothermal system eventually .更多还原