辽东三家子地区南辽河群斜长角闪岩的成因及地质意义

发布时间：2018-03-17 21:26

本文选题：辽东三家子地区　切入点：南辽河群　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：辽东三家子地区出露有一套古元古代角闪岩相变质基性岩石,由于缺乏系统的岩相学、矿物学及变质作用、地球化学以及年代学等研究,严重制约了对其成因和构造意义的探讨。针对这些亟待解决的问题,本文以三家子地区南辽河群斜长角闪岩为研究对象,在野外地质调查的基础上,对其进行了系统的岩相学、矿物学及变质作用、地球化学以及年代学研究,并结合前人有限的年代学和地球化学测试分析数据,探讨三家子地区南辽河群斜长角闪岩的成因,为南辽河群的沉积环境和当时的地壳演化提供有价值的资料。三家子地区斜长角闪岩出露于南辽河群的北段,主体呈层状、似层状或透镜状产出于变粒岩、浅粒岩和古元古代花岗岩中,岩石类型主要包括:斜长角闪岩和透辉斜长角闪岩。岩相学及变质作用研究表明,三家子地区斜长角闪岩主要由角闪石和斜长石组成,部分含有透辉石。根据岩石地球化学特征表明,三家子地区斜长角闪岩亏损Nb、Ta、Zr、Hf等高场强元素,其原岩属于拉斑玄武岩系列,来自于大陆岩石圈地幔,在形成过程中受到地壳物质的混染作用,表明其原岩的形成与岛弧或活动大陆边缘有关。矿物化学研究表明,三家子地区南辽河群斜长角闪岩总体上经历了高角闪岩相的区域变质作用类型,温压范围为:T=646-755℃,P=0.47-0.71Gpa。同位素年代学表明,南辽河群里尔峪组斜长角闪岩原岩年龄为2150Ma,变质年龄为1850Ma。结合该组变粒岩碎屑锆石年龄资料,说明南辽河群地层沉积开始于2150Ma左右,并在1850Ma左右发生变质作用形成区域上的胶-辽-吉造山带。
[Abstract]:There is a set of ancient amphibolite metamorphic basic rocks in Sanjiazi area, eastern Liaoning Province. Due to the lack of systematic studies on petrography, mineralogy and metamorphism, geochemistry and geochronology, etc., The discussion of its genesis and tectonic significance is seriously restricted. In view of these problems, this paper takes the amphibolite of the South Liaohe Group in Sanjiazi area as the research object, and makes a systematic petrographic study on it on the basis of the field geological survey. Mineralogy, metamorphism, geochemistry and chronology, combined with the limited geochronological and geochemical data, the origin of the amphibolite in the South Liaohe Group in Sanjiazi area is discussed. It provides valuable data for the sedimentary environment of the South Liaohe Group and the crustal evolution at that time. The amphibolite in the Sanjiazi area is exposed to the northern part of the South Liaohe Group, and its main body is layered, laminar or lenticular, which occurs in granulites. In shallow-grained rocks and Paleoproterozoic granites, the rock types mainly include: amphibolite and amphibolite. The petrographic and metamorphic studies show that the amphibolite is mainly composed of amphibolite and plagioclase. Some of them contain diopside. According to their petrogeochemical characteristics, the amphibolite in Sanjiazi area is depleted in high field strength elements, such as Nbtaitazhuanghf, which belongs to tholeiite series and is derived from the continental lithospheric mantle, the source rocks of which belong to the tholeiite series, and are derived from the continental lithospheric mantle. It is indicated that the formation of the original rock is related to the island arc or the active continental margin during the process of formation, and the mineralogical chemistry shows that the formation of the original rock is related to the formation of the island arc or the active continental margin. The amphibolite of the South Liaohe Group in Sanjiazi area has generally undergone the regional metamorphism of high amphibolite facies, and the range of temperature and pressure is in the range of 0.477-0.71Gpa.Isotope chronology shows that the amphibolite in the South Liaohe Group has a range of temperature and pressure of 0.47-0.71Gpa. The age of the amphibolite is 2150 Ma and the metamorphic age is 1850 Ma. combined with the zircon age of the metamorphic rocks, the stratigraphic deposits of the South Liaohe formation started at about 2150 Ma. The Jiao-Liao-Ji orogenic belt was formed by metamorphism around 1850 Ma.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P588.3

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