Latest Permian-earliest Triassic nappe structure in the Ulan Haya area on the northern margin of the North China platform

Abstract: The Latest Permian-earliest Triassic Menggusi-Panyangshan-Ulan Haya nappe structure was found in the Ulan Haya area on the northern margin of the North China platform. The greenstone series of the Neo-archean Serteng Mountain Group-complex is thrust over the limestone of the Sinian Shinagan Formation and Paleozoic clastic series. The thrust surface strikes in a nearly E-W direction with an extension length of> 50km, the vergence of thrusting is 180-230 ° and the displacement is> 4.5km. Middle Triassic (U-Pb age 231Ma) monzogranite intrudes along the thrust surface and is in turn overlain unconformably by the Middle Jurassic Daqingshan Formation. The discovery of this nappe structure changes the previous view that no latest Paleozoic large-scale nappe structure exists in the area and has great significance in understanding the tectonic development and crustal evolution in the North China platform (plate). This implies that a large-scale intracontinental orogenic event occurred in the North China platform (plate) in the terminal Late Paleozoic and it is inferred that its dynamic source was derived from tremendous compressional stress produced by the collision between the North China plate and South China plate.