【作者】 陈斌；

【导师】 周洪瑞；

【作者基本信息】 中国地质大学（北京） ， 古生物学与地层学， 2011， 硕士

【摘要】 研究区位于内蒙古东部,大兴安岭中段,构造位置属于兴蒙造山带(中亚造山带东段),晚古生代处于古亚洲洋的范围内。二叠纪时期古亚洲洋范围逐渐缩小至消亡,西伯利亚板块与华北板块最终碰撞闭合,褶皱造山形成兴蒙造山带。本文研究对象为中二叠统的哲斯组和上二叠统的林西组,通过剖面特征分析、岩石组合分析、砂岩骨架成分分析和岩石地球化学特征分析,分别对两者的沉积特征、沉积环境和大地构造背景进行研究。研究结果表明,研究区内哲斯组和林西组的碎屑粒度总体表现为由下至上逐渐变粗的特征,反映了当时由于构造抬升,海平面逐渐下降的过程。岩石及化石组合特征表明沉积环境早期较稳定,为浅海相沉积,后期构造活动增强,由浅海相过渡到海陆交互相沉积。再运用Dickinson、Bhatia和Roser等学者的构造环境判别图解等方法对哲斯组和林西组物源区的大地构造背景进行了砂岩碎屑分析,结果表明哲斯组的物源主要来自安第斯型大陆边缘,同时也含有来自大陆岛弧的成分特征,林西组的物源特征则主要表现为大陆岛弧。结合区域地质资料分析,二叠纪区内西伯利亚板块向南东俯冲于华北板块之下,板块缝合线位于研究区南部。研究区南部构造环境为活动大陆边缘,北部为大陆岛弧。研究区二叠纪的演化过程为,早二叠世火山活动活跃,至中二叠世环境趋于稳定,火山活动停止,由于板块间挤压碰撞,地壳逐渐抬升,到晚二叠世末期,海水逐渐退出本区。更多还原

【Abstract】 The study area located in the middle part of the Great Xing’an Range which is in the east of Inner Mongolian Autonomous Region, and belongs to the Xingmeng Orogenic Belt（eastern segment of Central Asian Orogenic Belt） tectonically. In late paleozoic, Paleo-Asian Ocean covered this area. From Permian, Paleo-Asian Ocean decreased,then the collision between Siberia Plate and North China Plate took place which led to the formation of Xingmeng Orogenic Belt. The subjects of this study is Zhesi Formation of middle Permian and Linxi Formation of upper Permian. The study uses the theory of stratigraphy, sedimentology and rock geochemistry to analyze the characteristics of sections, rock assemblages and the skeletal component of sandstone which are enssential to research the sedimentary environments and tectonic setting.The achievements of study are as follows: Firstly, the gain size of the two formations increases from bottom to top which represents a tectonical lifting event with waters regional regression. Secondly, rock assemblages and fossil data indicate that in the early stage the tectonic setting was stable and the strata was of shallow marine facies. Then the sedimentary facies transferred to paralic as the tectonic activity strengthened. Thirdly, by using achievements and diagrams of Dickinson, Bhatia and Roser, this study analyzes the geotectonic background of provenance and the conclusions are that the Zhesi Formation is mainly of active continental margin of Andes Type which also shows some characteristics of island arc, the Linxi Formation represents island arc environment.Based on regional geologic data and works mentioned above,the thesis can draw following conclusions: （1）Siberia Plate took Southeast subduction towards North China Plate and the geosuture might locate in the southern of the study area. （2）The tectonic setting of the southern part is active continental margin,and that of the northern part is island arc. （3）The evolutionary processes of the study area in Permian is that volcanic activities were active in P1,but stoped in P2,and tectonic environment became stable, then as the collision between Siberia Plate and North China Plate took place, the ground surface elevated which caused marine regression and despair in P₃. At the end of Permian, the study area was mainly in continental environment.更多还原