【作者】 李春雷；

【导师】 刘俊来；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2007， 硕士

【摘要】 漠河盆地是兴安岭盆地群中的一个独特盆地,具有独特的盆地展布方向和构造方向及成盆时代。沉积盆地所处的大地构造决定着盆地的类型,而基底的构造演化制约着盆地的演化类型,因此开展对漠河盆地构造特征及演化分析有助于我们更加清楚的认识东北地区盆地的构造特点、成盆动力学机制乃至晚中生代火成岩的成因,及其对于中国东部岩石圈伸展与减薄过程的正确理解。本文在借鉴前人大量研究成果基础上,综合野外调查测量、地球物理资料、分析测试资料及室内资料的整理,从构造-岩浆-盆地的演化关系入手,并结合分析区域动力学演化。研究发现漠河盆地主要由前中生代基底变质岩、晚侏罗世陆相碎屑沉积岩、早白垩世火山-火山碎屑岩三个大的组成单元。晚侏罗世时期,漠河盆地的主体构造格局呈近EW向展布,具有南北高,中部低的分带构造特征。这一时期形成了近EW向的基底断裂和局部地区NE向断裂,控制晚侏罗世沉积。同时,漠河地区在接受北部造山带及南部基底剥蚀的碎屑物共同沉积作用下,发育了额木尔河群冲积扇、辫状河、扇三角洲、辫状河三角洲和湖泊相沉积岩,形成了漠河前陆盆地。这一阶段的晚期,在盆地西部地区发生了由北向南逆冲-推覆作用,使得地层强烈变形,并在局部有变质作用发生。到了早白垩时期,漠河盆地原有的构造格局发生改造,形成了NW-SE向的堑垒相间的格局,早期形成的NE向断裂重新活化,并且发育了NNE向的断裂,控制了火山岩的分布。在129±17Ma～117±3Ma分别形成了塔木兰沟组、上库力组和之后的依列克得组中基性-中酸性火山熔岩,角度不整合覆盖在上侏罗统沉积岩之上,形成了双盖层的特点,形成了火山断陷盆地。漠河盆地是一个白垩纪火山断陷盆地与侏罗纪前陆盆地复合叠加的叠合盆地。在晚侏罗世时期,受到华北板块和西伯利亚板块的拼合、蒙古-鄂霍茨克洋关闭的影响,漠河地区受到近南北向强烈的挤压作用,造成盆地南北边缘隆起,形成了近东西向的控盆断裂,进入了前陆盆地演化阶段。在早白垩世时期,区域应力场发生重大转变,早期南北向挤压转变为NW-SE向伸展。由于剧烈的岩浆活动、地幔的上隆导致岩石圈发生伸展-减薄作用,在这种陆内到板缘的伸展环境下漠河地区发生断陷并形成大面积火山岩,进入火山断陷盆地演化阶段。更多还原

【Abstract】 The Mohe basin is a unique basin in Hinggan Mountains basin group. It is different from the other basins in its extension, directions of structural lines and age of basin formation. The type of basin was governed by tectonic setting, but the evolution of the basin is often controlled by the structural evolution of basin basement. The analysis of structural characteristics and evolution of the Mohe basin will contribute to our better understanding of the structural characteristic of basins in Northeast China, dynamic mechanisms of basin formation, the genesis of late Mesozoic igneous rock in adjacent areas, and the tectonic process of lithosphere extension and thinning in East China.Based on synthetic field geological survey, analysis of geophysical data, and geochemical analysis, this paper discussed the relationship between tectonic and magmatic processes and basin evolution, moreover studies of regional geodynamic evolution. We found the Mohe basin is constituted by three parts, a pre-Mesozoic basement of metamorphic rocks, a group of late Jurassic terrestrial clastic sedimentary rocks and a sequence of early Cretaceous volcano-pyroclastic rocks.During late Jurassic, the main tectonic framework of Mohe basin trends EW,with structural characteristic that the north and south parts are higher than the middle part. Basement faults which trends E-W and some small scale faults trending N-E are formed during the period. They controlled late Jurassic sedimentation. Affected by clastic deposition which denuded from the orogenic belts at the northern side and basement at the southern, sedimentary rocks of the Eumr River group are deposited. They are of alluvial fans, braid river, fan delta, braid river delat and lacustrine facies. As a result, a foreland basin was developed in Mohe area. Later in this stage, thrust-nappe from north to south, which caused intense deformation and regional metamorphism of the sedimentary rocks, was formed in the western part of basin.During early Cretaceous,the tectonic framework of Mohe basin was changed into the graben- horst pattern trending NE-SW. Pre-existing faults trending NE was reactivated, and faults trending NNE was developed. They controlled distribution ofvolcanic rocks of early Cretaceous. During 129±17Ma and 117±3Ma, intermediate basic- intermediate to acidic lava, of Tamulangou formation, Shangkuli formation and subsequent Yiliekede formation, was formed. An angular unconformity was formed between lower Cretaceous and upper Jurassic, leading to the occurrence of the bi-mantles of the basin with a volcanic faultdepression.The Mohe basin is a superimposed basin formed by a late volcanic fault basin of Cretaceous superimposed on a foreland basin of late Jurassic. In late Jurassic, influenced by closing of Mongolian -Okhotsk ocean due to convergence of North China plate with Siberia plate, a SN compression affected the Mohe basin. The southern and northern margins of the basin were uplifted due to faulting in EW direction. This is foreland stage of the Mohe basin. During early Cretaceous, there is a significant change of orientation of regional stress field. Regional stress field changed from SN compression into NW-SE extension. Extensive uplifting of mantle, magma activity resulted in subsequent lithosphere thinning. Large scale fault depression was formed in this area and extensive volcanic rocks were erupted at the background of extensional setting from intracontinental to plate margin. The Mohe basin at this stage was evolving into a new stage of volcanic fault depression.更多还原