广西西大明山地区燕山期岩浆活动及其成矿效应

发布时间：2018-02-03 04:48

  本文关键词： 燕山期 岩石成因 地球化学 西大明山　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】：西大明山矿集区是2015年新探明的具有良好经济前景的钨-锌-银多金属矿集区,位于钦杭成矿带上西南部和西大明山凸起的中西部,与华南地区燕山晚期的岩浆活动和成矿作用的关系十分紧密。在前人研究基础上,本文选择西大明山矿集区内燕山期岩浆岩为研究对象,开展岩石地球化学分析、年代学分析和同位素地球化学分析;并与丹池成矿带内岩浆岩对比分析,查明西大明山矿集区燕山期岩浆岩的地球化学特征和成因,探讨了西大明山矿集区燕山晚期成岩成矿作用。罗维花岗岩岩体与丹池成矿带上的其他岩体类似,为同碰撞向板内构造环境转换的环境下形成的过铝质碱性A型花岗岩。罗维隐伏岩体的微量元素蛛网图显示样品相对富集Rb、U、Nd、Pb、Th等大离子亲石元素,亏损Ba、Sr、Ti等高场强元素;稀土配分模式图为具明显负铕(Eu)异常的右倾的“V”字形配分曲线。锆石U-Pb测年结果为94.3±1.9Ma,花岗岩εHf(t)值为-3~-7,显示其来源于下地壳。那宁山顶出露的石英斑岩蚀变严重,其锆石U-Pb谐和年龄为93.46±0.46Ma,属于燕山晚期岩浆岩,与该地区的成岩成矿年龄一致,并且与矿集区内的成矿作用有密切联系。辉绿岩为拉张环境下形成的碱性大洋环境玄武岩;样品微量元素曲线显示板内玄武岩的特征;稀土配分曲线显示为壳源岩浆的特征的无Eu异常的右倾曲线。辉绿岩锆石U-Pb年龄中有一期94Ma左右的年龄,与矿集区内酸性岩形成时代相近。辉绿岩中成矿元素(Mn、Cu、Zn、Ni)含量较高,尤其Mn含量最高,可能与矿集区内锰矿的形成有关。以上研究显示,西大明山矿集区内燕山期岩浆岩活动时间与华南地区燕山晚期大规模岩浆活动时限基本一致。通过搜集前人资料,西大明山矿集区内典型矿床流体包裹体H-O同位素中,δ18O-δD的值显示矿集区内成矿流体主要为岩浆水。矿石中硫化物的S、Pb同位素显示其金属成矿物质主要来自岩浆岩,且Pb同位素与罗维隐伏岩体Pb同位素基本一致,表明该地区燕山晚期岩浆岩与成矿有密切的联系。矿集区内矿体空间展布特征、元素地球化学、同位素组成特征等显示该区为一个与深部隐伏岩体密切相关的岩浆热液成矿系统。
[Abstract]:In 2015, the West Daming Mountain ore concentration area is a newly proved tungsten, zinc-silver polymetallic area with good economic prospects. It is located in the southwest of the Qinghang metallogenic belt and the central and western part of the West Daming Mountain uplift. It is closely related to the late Yanshanian magmatism and mineralization in South China. On the basis of previous studies, this paper chooses Yanshanian magmatic rocks in the West Daming Mountain ore concentration area as the object of study. Rock geochemistry analysis, geochronology analysis and isotopic geochemical analysis are carried out. The geochemical characteristics and genesis of Yanshanian magmatic rocks in the West Daming Mountain ore concentration area are studied by comparing with the magmatic rocks in the Danchi metallogenic belt. This paper discusses the late Yanshanian diagenesis and mineralization in the West Daming Mountain ore concentration area. The Luowei granite body is similar to other rock bodies in the Danchi metallogenic belt. The trace element cobwebs of the Luowei cryptic rock show that the samples are relatively rich in RbHU Ndndlb Pb, which is formed in the environment of the concollision to the intraplate tectonic environment. Large ion lithophile elements such as Th and depleted high field strength elements such as Ba-Sr-Ti; The REE partition pattern is a "V" zigzag partition curve with obvious negative europium EU) anomaly. The zircon U-Pb dating results are 94.3 卤1.9 Ma. The 蔚 Hft value of the granite is -3 ~ (-7), indicating that it originated from the lower crust. The quartz porphyry exposed from the top of Nanning is seriously altered, and its zircon U-Pb harmonic age is 93.46 卤0.46 Ma. It belongs to the late Yanshanian magmatic rock, which is consistent with the diagenetic and metallogenic age of the area, and is closely related to the mineralization in the ore concentration area. The diabase is an alkaline oceanic basalt formed in the extensional environment. The characteristics of trace element curve display basalt in the sample; The REE distribution curve shows the characteristics of crust-derived magma with no EU anomaly and the U-Pb zircon age of diabase is about 94 Ma. It is similar to the formation age of acidic rocks in the ore concentration area. The content of the ore-forming element of diabase is high, especially the mn content is the highest. It may be related to the formation of manganese ore in the ore concentration area. The Yanshanian magmatic activity time in the West Daming Mountain Ore concentration area is basically consistent with that of the late Yanshanian magmatic activities in South China. In the H-O isotopes of fluid inclusions of typical deposits in the West Daming Mountain ore concentration area, the values of 未 18O- 未 D indicate that the ore-forming fluids are mainly magmatic water and S of sulphide in ore. The Pb isotope shows that the metallogenic material mainly comes from magmatic rocks, and the Pb isotopes are basically consistent with the Pb isotopes of the Lowe concealed rock mass. The results show that the late Yanshanian magmatic rocks are closely related to mineralization. The spatial distribution characteristics and element geochemistry of orebodies in the ore concentration area. The isotopic composition features indicate that the area is a magmatic hydrothermal metallogenic system closely related to the deep concealed rock mass.
【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】：P612;P588.11
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本文编号：1486463