THREE DIFFERENT TYPES OF PHANEROZOIC OROGENESIS OF NORTHERN BORDER AREA OF NORTH CHINA CRATON

Three different types of Phanerozoic orogenesis are identified in the northern border area of North China Craton.In the Paleozoic era,the northern border area of North China Craton belonged to the tectonic domain of south peri-Paleozoic ocean and is characterized by subduction-collision orogenesis,leading to the formation of EW-to ENE-trending folds,thrust faults,nappes and ductile shear zones etc.In the Mesozoic era,it was located in the interior of east Eurasia continent and belonged to west peri-Pacific tectonic domain and underwent intracontinental compression orogenesis separated by 6 periods of regional unconformity,more than 5 periods of regional volcanic eruption and plutonism,and strong compressional deformation,producing E-W-,NE-, and NNE-trending folds,thrust faults,nappes,ductile shear zones in the whole area,and structural systems of solid state plastic flow and ring structures in some local areas due to northwestward to westward increasing compression arising mainly from the subduction of the Pacific plate.In the Cenozoic era,it experienced intracontinental extensional orogenesis marked by widespread rifting and extensional faulting with weak folding,giving rise eventually to the present-day tectonogeomorphic features of basins and ranges.This regional extension is believed to be caused by the westward motion of Eurasia plate from the subduction zone.
The transfer of these orogenesis types occurred respectively in the early-middle Triassic and late Cretaceous.