内蒙古固阳地区石炭纪花岗岩类岩石学特征研究

发布时间：2018-06-10 09:09

本文选题：花岗岩类 + 岩石学特征　；参考：《石家庄经济学院》2015年硕士论文

【摘要】：内蒙古固阳地区位于华北板块北缘中段,索伦缝合线和集宁—隆化断裂以南。一般认为,古亚洲洋板块向华北板块的俯冲时间为古生代时期,对本区石炭纪花岗岩类岩石的岩石学特征、岩石成因以及构造背景的研究,对更好的认识石炭纪花岗岩类乃至整个古生代的花岗岩类以及整个华北板块的构造演化有重要的理论意义。本论文依托于内蒙古自治区大老虎店等四幅1:5万区域地质矿产调查,在基于前人研究成果的基础上,通过对固阳地区石炭纪花岗岩类的分布、产出规模、以及岩石学特征的研究,利用固阳地区花岗岩类的主量元素、微量元素以及稀土元素并结合花岗岩新的理论研究成果,对固阳地区石炭纪花岗岩类的形成原因及构造背景进行了进一步的探讨,主要得到了以下认识:(1)固阳地区石炭纪花岗岩类在岩性上主要有三种,分别是黑云母花岗闪长岩、石英二长岩和黑云母正长花岗岩,本文主要对黑云母花岗闪长岩和石英二长岩进行了研究,通过对其地球化学元素特征的分析,两者均为准铝质高钾钙碱性I型花岗岩类。(2)黑云母花岗闪长岩和石英二长岩均具有较高的结晶分异指数(DI),说明其岩浆在演化过程中经历了较好的结晶分异作用。(3)从微量元素和稀土元素含量特征来看,两者均具有高Sr、低Yb、轻重稀土高度分馏的特点,再结合其具有较高的Al2O3(大于等于15%)及较小的Mg O(小于等于3%)等主量元素的特点,笔者认为固阳地区石炭纪花岗岩类为与典型埃达克岩具有相似地球化学特征的埃达克质岩。(4)通过对固阳地区石炭纪花岗岩类的形成原因和构造背景的分析可知,该地区石炭纪花岗岩类在成因上为古亚洲洋板块向华北板块俯冲作用下形成的壳幔混合型幔源岩浆熔融而成;在构造背景上,黑云母花岗闪长岩形成于板块消减过程的大陆弧环境,石英二长岩形成于板块俯冲作用的晚造山期环境。
[Abstract]:Guyang area, Inner Mongolia is located in the middle of the northern margin of North China plate, south of Soren suture line and Jining-uplift fault. It is generally believed that the subduction time of the paleo-Asian oceanic plate to the North China plate was Paleozoic, and the petrological characteristics, petrogenesis and tectonic setting of the Carboniferous granitic rocks in the area were studied. It is of great theoretical significance to better understand the tectonic evolution of the Carboniferous granitoids and the entire Paleozoic granitoids and the North China plate. This paper is based on the investigation of regional geological and mineral resources of 11: 50, 000 in four pieces of Daghudian, Inner Mongolia Autonomous region. Based on the previous research results, the distribution and production scale of Carboniferous granites in Guyang area are studied. And the study of petrological characteristics, using the main elements, trace elements and rare earth elements of granites in Guyang area, and combining with the new theoretical research results of granite. The formation causes and tectonic background of Carboniferous granites in Guyang area are further discussed. The main conclusions are as follows: (1) Carboniferous granodiorites in Guyang area are mainly of three kinds in lithology, which are biotite granodiorite. Quartz monzolite and biotite syenite granodiorite and quartz monzonite are studied in this paper. Both quasi aluminous high potassium calc alkaline I type granitic granodiorite and quartz monzonite have higher crystallization differentiation index, indicating that their magma experienced better crystallization differentiation in the evolution process. From the characteristics of trace elements and rare earth elements, Both have the characteristics of high Sr, low Yb, and high fractionation of heavy and heavy rare earths, combined with the characteristics of higher Al _ 2O _ 3 (> 15) and smaller MgO (less than and equal to 3), etc. The authors consider that the Carboniferous granitic rocks in Guyang area are adakitic rocks with similar geochemical characteristics as typical adakites. The formation causes and tectonic background of Carboniferous granitoids in Guyang area are analyzed. The Carboniferous granitoids were formed from the melting of the crust and mantle mixed mantle magma formed by the subduction of the paleo-Asian oceanic plate to the North China plate. Biotite granodiorite was formed in the continental arc environment during plate subduction, while quartz monzonite was formed in the late orogenic environment of plate subduction.
【学位授予单位】：石家庄经济学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.121

【参考文献】