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 Tarimplate 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.