四川理塘地区花岗岩地质地球化学特征及其成矿意义

发布时间：2018-03-01 21:47

本文关键词： 理塘地区黑云母二长花岗岩地球化学特征成矿意义　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】：“三江”地区一直以来都是我国地质学家研究的重点区域,义敦岛弧碰撞造山带是其研究的重要组成部分。勇杰岩体和二四九岩体分布于岛弧区内,但均以断续形态、较小面积出露,对区域格架的研究有着不可替代的作用。本次研究主要从岩石学、地球化学两个方面分析讨论花岗岩岩体岩石地球化学特征,并分析其成因。为制约二四九岩体和勇杰岩体侵位时代和源区,本文利用高精度LA-ICP-MS微区原位分析技术对两种花岗岩中的锆石进行U-Pb同位素定年。锆石地质年代学研究显示,勇杰岩体中粒黑云母二长花岗岩侵位年龄为221.0±1.9Ma,细粒黑云母二长花岗岩侵位年龄为226.1±1.7Ma,二四九岩体细粒黑云母二长花岗岩226.7±2.1Ma,侵位时代均为晚三叠世。通过分别对两种花岗岩地球化学主量元素、微量元素和稀土元素对比分析,配分曲线的高度一致说明两者为同源花岗岩,且配分模式与岛弧岩浆岩的模式十分吻合。再通过构造环境投图判断,同样显示两种花岗岩为典型岛弧型岩浆岩。因此,本文认为岩体主要由晚三叠世黑云母二长花岗岩组成,属于义敦-沙鲁里岛弧岩带。从侵位时代(226-221Ma)判断,二四九岩体与勇杰岩体均为印支期大规模俯冲造山作用下的产物。本文通过对比普朗斑岩型铜矿床岩体岩体地球化学特征,探讨理塘地区花岗岩体的成矿意义,结合高度一致的年代学特征,成岩时代均为221Ma左右,认为二四九岩体、勇杰岩体具有在区域内形成斑岩型铜矿的潜力。
[Abstract]:The "Sanjiang" area has always been the focus of geologists in China, and the Yidun island arc collision orogenic belt is an important part of the study. The Yongjie rock mass and the 249 rock mass are distributed in the island arc area, but they are in intermittent form. The small area outcrop plays an irreplaceable role in the study of the regional framework. This study mainly discusses the petrogeochemical characteristics of the granite rock mass from two aspects: petrology and geochemistry. In order to restrict the emplacement age and source region of the 249 and Yongjie intrusions, the U-Pb isotopic dating of zircons from two kinds of granites was performed by using high-precision LA-ICP-MS microanalysis technique. The emplacement age of biotite monzogranite in Yongjie rock mass is 221.0 卤1.9 Ma., the emplacement age of fine-grained biotite monzogranite is 226.1 卤1.7 Ma., and that of 249 rock mass is 226.7 卤2.1 Ma.The emplacement age is all late Triassic. Main geochemical elements of granite, By contrast analysis of trace elements and rare earth elements, the height of the partition curve shows that they are homologous granite, and the distribution model is in good agreement with the model of island arc magma. It is also shown that the two types of granites are typical island arc type magmatic rocks. Therefore, it is considered that the rock mass is mainly composed of late Triassic biotite monzonitic granite, which belongs to the Yidong-Shaluli island arc rock belt, judging from the emplacement age of 226-221 Ma. The 249 rock mass and the Yongjie rock mass are both the products of Indosinian large-scale subduction orogeny. By comparing the geochemical characteristics of rock mass of Plang porphyry copper deposit, the metallogenic significance of granite body in Litang area is discussed in this paper. In combination with the highly consistent chronological characteristics, the diagenetic age is about 221 Ma. It is considered that the 249 rock mass and the Yongjie rock body have the potential to form porphyry copper deposits in the region.
【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】：P588.121;P612

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