Mesozoic-Cenozoic tectonic framework of southern Northeast Asia
GE Xiao-hong, MA Wen-pu (Geosciences College, Jilin University, Changchun 130061, China; China University of Geosciences, Beijing 100083, China)
Southern Northeast Asia covers the area where the West Pacific tectonic belt, North America or Okhotsk Plate, Central Asia orogenic belt, the Sino-Korea and the Yangtze blocks meet together. In the course of Pangaea and supercontinent assembling and disintegration this belt has experienced multple tectonic events since the Mesozoic and has acquired a rather complicated structure. The tectonic affiliation of many middle-scaled and small scaled blocks, including that of the Korea Peninsula, have long been disputed. Based on recent obtained SHRIMP geochronologic data and palaeobiogeographic and tectonic evidences, the authores in this paper deem that the Korea Peninsula and the Hida-Oki belt of Japan might have been affiliated to the Sino-Korea Plate during the Paleozoic, Sakhalin-Hokkaido massifs, to the North America Plate, and the Bureya-Jiamusi-Khanka massifs, to Siberia Plate. Since the 80's of last century most authors have regarded the discussed area as connected with the westward subduction of the West Pacific oceanic crust under Northeast Asia since the Mesozoic. But recently more and more scholars prefer to interpret the geodynamics of crust-lithospheric thinning of Eastern Asia from continent collision and extrusion. The southern Northeast Asia belt has experienced two stages of tectonic development: consumption of the Palaeo-Asian Ocean during the late Hercynian-Indosinian epoch and convergence-collision between the southern and the northern continents during the late Yanshanian epoch (late Jurassic to early Cretaceous). It was these processes that resulted in the extension of the Central Asia orogenic belt to the Yinshan-Yanshan region at the northern edge of the Sino-Korea plate and the formation of a plateau morphology caused by crustal thickening similar to the Qinghai-Tibet Plateau today. In the late Cretaceous to Palaeogene, the crust-lithosphere thinning of this area caused the appearance of large scale extension type Basin-Range structure. In the meantime, the northward section of the Tanlu faults system underwent sinistral displacement. Along the East Asia continental margin occurred accretion, and the rotation of the Pacific plate caused compressional deformation and extensive peneplanation. Many heavy metal and noble metal placeres in the fault basins bordering Palaogene uplifts in Heilongjiang and Jinin were formed in this period. In the Neogene the crust-lithosphere further thinned and the continental rifts developed into the East Asia-Pacific rift belt and the NNE-trending Basin-Range structure came to appear. The Sea of Japan opened, the Western Pacific island arcs appeared. The recent topographic steps of China was initiated at the end of the Early Pleistocene. But the present geomorphic frame that controls the nowadays climate and river system was not formed until post-late Pleistocene time.