内蒙古阿拉善南部地区变质岩特征与意义

发布时间：2018-04-05 00:37

  本文选题：元古代　切入点：阿拉善　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：内蒙古阿拉善南部地区的前寒武纪变质岩石可分为乌拉山岩群和阿拉善岩群。阿拉善岩群可划分为哈乌拉岩组、德尔和通特岩组、祖宗毛道岩组。本文针对南部区出露的乌拉山岩群、哈乌拉岩组、祖宗毛道岩组进行研究。研究区内的区域变质作用为三期,第一期变质相为角闪岩相;第二期变质相为高绿片岩相-低角闪岩相;第三期变质相为高绿片岩相。乌拉山岩群中三期变质特点都较为明显,阿拉善岩群的哈乌拉岩组主要发育第二期和第三期变质,祖宗毛道岩组主要发育第三期变质。乌拉山岩群主要岩石组合为斜长角闪岩、黑云斜长片麻岩、变粒岩,原岩为一套碎屑沉积岩和火山岩的组合,变质温度为500~750℃,压力为0.35~0.45GPa。阿拉善岩群哈乌拉岩组岩石组合为斜长角闪岩、黑云斜长片麻岩、变粒岩,原岩为一套火山岩为主夹有碎屑沉积岩的变质表壳岩,变质温度为600~720℃,压力为0.5GPa左右。祖宗毛道岩组岩石类型为二云母石英片岩、二长变粒岩。原岩为一套碎屑沉积岩和火山岩的组合,变质温度为400~530℃,压力为0.6GPa。将研究区内的变质岩与同时期华北板块的变质岩进行对比,变质程度较华北板块低,应处于不同的区域变质环境。推测在元古代时期研究区与华北板块并不同属一个大地构造单元。
[Abstract]:The Precambrian metamorphic rocks in the southern part of Alashan, Inner Mongolia can be divided into the Wulashan rock group and the Alashan rock group.The Alashan rock group can be divided into the Hawulan formation, the Del and Tonte formation, and the ancestral Maodaoyan formation.In this paper, the outcropping of the Wulashan rock group, the Hawulan formation and the ancestral Maodaoyan formation in the southern region are studied.The regional metamorphism in the study area is divided into three stages, the first metamorphic facies is amphibolite facies, the second metamorphic facies is high greenschist facies-low amphibolite facies and the third metamorphic facies is high greenschist facies.The characteristics of three metamorphic stages in the Wulashan rock group are obvious. The second and third metamorphic stages are mainly developed in the Hawularite formation of the Alashan rock group and the third metamorphism in the ancestral Maodaoyan formation.The main rock assemblages of the Wulashan rock group are amphibolite, biotite gneiss, granulite, and the primary rock is a combination of clastic sedimentary rocks and volcanic rocks. The metamorphic temperature is 500 ~ 750 鈩，

本文编号：1712445