A preliminary study of the structure and reformation of the Permian and Carboniferous strata in Yingen-Ejin basin and its periphery

In this study, structure deformation features of the Carboniferous, Permian and Meso-Cenozoic strata were analyzed in Yingen-Ejin basin and its periphery, and geological survey was conducted mainly based on geophysical prospecting and drilling in the interior of the basin. The deformation of the Carboniferous and Permian outcrops is stronger than that in the interior of the basin, and stronger in Beishan than in Honggeershan. The tectonic deformation stages and dynamic mechanism after Permian were preliminarily discussed. Four tectonic stages, i.e., Late Variscan, Early Yanshanian, Late Yanshanian and Himalayan tectonic movement, were distinguished. The deformation was strong in the first period. The second phase deformation is the strongest in the region in that large-scale nappe structure and regional uplift were formed during this period; the overall tectonic pattern was formed in the Late Jurassic. The third and fourth stages were mainly characterized by differential uplifting and subsidence, with the dynamic mechanism being separately controlled by the remote effects of the subductions of the Pacific plate under the North China block and the subduction of the India plate under the Eurasia. The source rock of Carboniferous-Permian was buried most deeply with the formation of oil until the end of Early Cretaceous. Furthermore, the structural activities were insignificant after the Early Cretaceous, which was favorable for the formation of hydrocarbon reservoir.