西藏古堆地区金锑多金属矿床地球化学特征及成矿模式

发布时间：2018-06-26 09:43

  本文选题：矿床地球化学 + 流体包裹体　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：西藏冈底斯-喜马拉雅造山系中的古堆地区,位于藏南江孜-隆子金锑多金属成矿带上,成矿潜力巨大。该地区地质工作程度不高,多金属矿床的勘查程度偏低,对区内典型多金属矿床的地球化学特征及成矿流体进行研究还十分薄弱,也缺乏区域成矿规律的总结与研究。研究区的多金属矿床与三叠系涅如组二段、三段,侏罗系遮拉组联系紧密,岩性都以泥质成分为主,普遍含碳较高,并含有灰岩、铁硅结核,推断沉积环境为差异升降下的水下扇沉积的进积型地层对成矿较为有利。碰撞造山和拆离伸展两个阶段形成的压扭、伸展作用叠加形成的近EW、NE和NW向断裂构造及次级断裂交汇处,是有利的成矿控矿构造。古近纪40Ma左右的花岗岩与金锑多金属成矿关系密切,新近纪20Ma左右的花岗岩与锑铅锌关系密切。本文取得如下成果和认识:(1)流体包裹体类型主要有水溶液包裹体(W型)、CO2-H2O型包裹体(C型),少量气液两相包裹体,无含子矿物多相包裹体。三个典型矿床均一温度为170-220℃,盐度平均6.82%,成矿压力为50-55MPa,成矿深度为1.5-2.5km,可判断其属于浅成低温热液型矿床;激光拉曼光谱分析得出成矿流体的气体成分都以CO2为主,推断古堆地区多金属矿床流体都为中低温低盐度NaCl-H2O热液体系。(2)氢、氧、硫、铅同位素组成显示,成矿流体主要为建造水,部分为变质水与建造水的混合。硫具有深源岩浆硫的特征,铅具有从造山带向上地壳铅演化的趋势,形成了与围岩相同的铅同位素组成。(3)分析了控矿因素,建立了研究区成矿模式图,认为达拉岩体岩浆活动为成矿物质提供了初始热源及运移动力,地幔热液的上涌及中酸性次火山岩侵入作用,产生动力热液变质作用并汲取多种成矿元素,使之活化成含矿热液,并且迁移、沉淀,在区内一系列近EW向主断裂与近SN向次级断裂交汇处富集成矿。
[Abstract]:The Gudui area of the Gangdis Himalayan orogenic system in Tibet is located in the Jiangzi-Longzi gold-antimony polymetallic metallogenic belt in southern Tibet with great metallogenic potential. The degree of geological work in this area is not high and the degree of exploration of polymetallic deposits is on the low side. The geochemical characteristics and ore-forming fluids of typical polymetallic deposits in this area are still very weak, and the summary and study of regional metallogenic laws are also lacking. The polymetallic deposits in the study area are closely related to the second, third and Jurassic Chola formations of the Triassic, and their lithology is dominated by muddy compositions, generally with high carbon content, and with limestone and iron-silicon nodules. It is inferred that the precession of the subaqueous fan deposits in the depositional environment is favorable for metallogenesis. The compression and torsion formed in the two stages of collision orogeny and detachment extension, the superposition of extensional action to form near EWU NE and NW trending fault structures and the junction of secondary faults are favorable ore-controlling structures. The granites about 40 Ma in Paleogene are closely related to Au-SB polymetallic mineralization, while the granites of about 20 Ma in Neogene are closely related to antimony, lead and zinc. The main results of this paper are as follows: (1) the types of fluid inclusions are mainly aqueous inclusions (W type) and CO _ 2-H _ 2O inclusions (C type), a small amount of gas-liquid two-phase inclusions, and no multiphase inclusions containing sub-minerals. The homogenization temperature of the three typical deposits is 170-220 鈩，

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