本文選題：元古代　切入點：阿拉善　出處：《中國地質大學(北京)》2017年碩士論文

【摘要】：內蒙古阿拉善南部地區(qū)的前寒武紀變質巖石可分為烏拉山巖群和阿拉善巖群。阿拉善巖群可劃分為哈烏拉巖組、德爾和通特巖組、祖宗毛道巖組。本文針對南部區(qū)出露的烏拉山巖群、哈烏拉巖組、祖宗毛道巖組進行研究。研究區(qū)內的區(qū)域變質作用為三期,第一期變質相為角閃巖相;第二期變質相為高綠片巖相-低角閃巖相;第三期變質相為高綠片巖相。烏拉山巖群中三期變質特點都較為明顯,阿拉善巖群的哈烏拉巖組主要發(fā)育第二期和第三期變質,祖宗毛道巖組主要發(fā)育第三期變質。烏拉山巖群主要巖石組合為斜長角閃巖、黑云斜長片麻巖、變粒巖,原巖為一套碎屑沉積巖和火山巖的組合,變質溫度為500~750℃,壓力為0.35~0.45GPa。阿拉善巖群哈烏拉巖組巖石組合為斜長角閃巖、黑云斜長片麻巖、變粒巖,原巖為一套火山巖為主夾有碎屑沉積巖的變質表殼巖,變質溫度為600~720℃,壓力為0.5GPa左右。祖宗毛道巖組巖石類型為二云母石英片巖、二長變粒巖。原巖為一套碎屑沉積巖和火山巖的組合,變質溫度為400~530℃,壓力為0.6GPa。將研究區(qū)內的變質巖與同時期華北板塊的變質巖進行對比,變質程度較華北板塊低,應處于不同的區(qū)域變質環(huán)境。推測在元古代時期研究區(qū)與華北板塊并不同屬一個大地構造單元。
[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，

本文編號：1712445