青海同德加吾矿区岩浆作用及钨矿成矿机理研究

发布时间：2018-01-13 17:07

本文关键词：青海同德加吾矿区岩浆作用及钨矿成矿机理研究　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：青海同德加吾矿区处于青海南山微造山带,属于西秦岭造山带与东昆仑造山带的接触部位。本文通过岩相学、全岩地球化学、矿物学、流体地球化学的研究,结合前人资料,进一步阐述加吾矿区岩浆岩的成因与金属矿物成因,探讨了区域动力学、热力学特征及白钨矿成矿机理,对于指导该区地质找矿具有重要的意义。通过本次研究,取得了以下主要成果与认识:加吾矿区花岗岩类均为I型花岗岩。花岗闪长岩具有富钠、贫钾、过铝质、高钾钙碱性花岗岩特征;富集大离子亲石元素(LILE):铷、钡、铀、钍,轻度亏损高场强元素(HFSE):铌、钽、钛;轻重稀土分馏明显,铕、铈异常不明显,锶轻微负异常。花岗斑岩具有富钠、贫钾、过铝质、钙碱性花岗岩特征;富集大离子亲石元素(LILE):铷、钡,亏损高场强元素(HFSE):铌、钽、钛;轻重稀土的分异较大,钇值含量较低,同时具有弱铕负异常,锶含量低。结合区域动力学研究及成岩时代分析,花岗斑岩源自老地壳,花岗闪长岩源自岩石圈地幔。加吾矿区不同产出状态含矿石英脉流体包裹体类型主要为富液包裹体,成矿流体温度总体在200~290°C,盐度总体小于10wt%Na Cl,显示出浅成低温热液特征。成矿流体的氢氧同位素特征指示其很可能来源于岩浆流体,同时不排除混入少量变质流体的可能性。电子探针分析显示白钨矿主要成分与理论值相比,钨含量偏低,而钙含量略偏高,钼含量低于0.1%。通过与不同类型白钨矿成分组成进行对比,加吾白钨矿显示出石英脉型白钨矿的特点;同时,WO3-Ca O关系和白钨矿阳离子W-Mo-Ca三角图解分析,加吾白钨矿均显示为石英脉型白钨矿。综上所述,加吾钨矿床成矿流体表现出浅成低温热液特征,其成因上与该区花岗岩类关系密切,矿床类型为石英脉型白钨矿。
[Abstract]:Tongde Jiawu ore area in Qinghai is located in the Nanshan microorogenic belt, which belongs to the contact site between the West Qinling orogenic belt and the East Kunlun orogenic belt. This paper studies the petrography, whole rock geochemistry, mineralogy and fluid geochemistry. Based on the previous data, the genesis of magmatic rocks and metal minerals in Jiawu mining area is further expounded, and the regional dynamics, thermodynamic characteristics and metallogenic mechanism of scheelite are discussed. It is of great significance to guide geological prospecting in this area. Through this study, the following main achievements and understandings have been obtained: the granitoids in Jiawu mining area are all I-type granites, and granodiorite is rich in sodium and poor in potassium. Peraluminous, high-potassium calc-alkaline granites; Enrichment of large ion lithophile elements Lilei: rubidium, barium, uranium, thorium, slightly depleted high field strength elements HFSE: niobium, tantalum, titanium; The fractionation of heavy and heavy rare earths is obvious, the anomaly of europium and cerium is not obvious, and the anomaly of strontium is slightly negative. The granitic porphyry is characterized by rich in sodium, poor in potassium, peraluminous and calc-alkaline granite. Enrichment of large ion lithophile elements Lilei: rubidium, barium, depleted high field strength elements HFSE: niobium, tantalum, titanium; The heavy and heavy rare earth elements have large differentiation, low yttrium content, weak europium negative anomaly and low strontium content. Combined with regional dynamics and diagenetic age analysis, granitic porphyry originated from the old crust. The granodiorite originates from the lithospheric mantle. The fluid inclusions of different ore-bearing veins in Jiawu ore area are mainly liquid-rich inclusions, and the temperature of ore-forming fluid is generally at 290 掳C. The salinity is less than 10 wtNa Cl, showing the characteristics of epithermal hydrothermal solution. The hydrogen and oxygen isotopic characteristics of the ore-forming fluid indicate that it probably originated from the magmatic fluid. At the same time, the possibility of mixing a small amount of metamorphic fluid is not excluded. Electron probe analysis shows that the main composition of scheelite is lower than the theoretical value, and the content of calcium is slightly higher. The molybdenum content is less than 0.1%. Compared with the composition of different types of scheelite, Jiawu scheelite shows the characteristics of quartz vein type scheelite. At the same time, the WO _ 3-CaO relationship and W-Mo-Ca triangular diagram analysis of scheelite show that the scheelite is quartz vein type scheelite. The ore-forming fluid of Jiawu tungsten deposit shows the characteristics of epithermal hydrothermal formation, and its genesis is closely related to the granitic type in this area, and the type of deposit is quartz vein type scheelite deposit.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.67

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