塔里木盆地西北缘乌什西次凹的地层系统和构造特征OA北大核心CSTPCD

The western subsag of Wushi Sag is located in the northwest margin of Tarim Basin and belongs to Kuqa Depression.It is located between the main mountain range of the South Tianshan Mountain(Halke Mountains)and the Kalpin-Wenshu uplift.In terms of regional tectonic framework,it is the natural extension of Tarim Craton to the northwest.The Akqi fault on the northern margin of western subsag of Wushi Sag is the boundary between the southern Tianshan orogenic belt and the Tarim Craton.A Late Precambrian to Paleozoic stratigraphic system similar to that on the Kalpin-Wenshu uplift,including Cambrian,Ordovician and Carboniferous source rocks,is developed in the subsag.Neogene-Quaternary clastic formation directly unconformably overlie the deformed Paleozoic passive continental margin clastic-carbonate formations.In profile,it thickens towards the South Tianshan and thins towards the Tarim Craton,showing a typical profile feature of foreland basin.This is a Late Cenozoic intracontinental foreland basin superimposed on the Late Hercynian to Yanshanian paleo-uplift.There are three major deformation stages,namely Middle Hercynian,Late Hercynian-Indosinian and Late Himalayan or Late Alpine.The deformation is dominated by the thick-skinned structures,while the thin-skinned structure is not developed.On the plane,the main structural line strikes NE-SW.On the profile,the thrusts are mainly from the South Tianshan to the Tarim Basin,forming a basement-involved thrust belt.