柴达木盆地断裂体系划分及其成盆动力学意义

断裂体系是具有成生联系的各项不同产状、不同等级、不同性质和不同序次的断层组合,柴达木盆地受到印度、西伯利亚和太平洋三大板块的共同影响,围绕中部刚性基底周边发育北部祁连山、南部东昆仑山及西部阿尔金山三大断裂体系,每个断裂体系都是由主要断裂及其伴生的断层相关褶皱组成三排波浪式冲断构造,低序次断层及其相关褶皱呈斜列式分布于其间,整个盆地可以看成三大断裂体系叠合的产物,其根本动力学背景是柴达木地块受到南部印度板块向北挤压、北部阿拉善地块的阻挡及东侧华北板块和西侧塔里木板块的侧滑而形成的力偶环境,结合平衡剖面分析结果提出盆地发展经历了早—中侏罗世南北向拉张、新生代多次幕式挤压并叠加东西向侧向走滑、并于第四纪形成现今的构造面貌的发展历史。

Dividing of Fault System and Its Implication for Formation Dynamics in Qaidam Basin

The fault system is a combination which consist of all types of fault element,and the element maybe occurred in different shape,different grade,different feature and different level.Under the common and integrated influence of the India plate,the Siberia plate and the Pacific plate,three fault systems,that is,the northern Qilian mountain fault system,the southern Kunlun mountain fault system and the western Altun mountain fault system,were developed around the middle rigid block in Qaidam basin.Each of the fault system contains three thrust structural belts which consists of several main faults and their relevant folds; and the sublevel faults and their relevant folds distributed within the thrust structural belts diagonally;and the structural framework of Qaidam basin could be regarded as a superposition of the three great fault system.The basic dynamic setting is that the Qaidam block was compressed by India plate from south to north on the southern margin,resisted by Alashan plate from north to south on the northern margin and side-slipped from north China plate on eastern margin and from Tarim plate on western margin.Combining the analysis of balance profile,the preliminary dynamic evolution model of the basin was established,that is,the Qaidam Basin experienced a pull-apart within the period of early to middle Jurassic and the poly-episodic compressions and composited sideslips within the period of Cenozoic,and finally the structural framework of Qaidam basin was formed within Quaternary.