POTENTIAL GEODYNAMIC LINK BETWEEN THE PALEO-ASIAN OCEAN AND THE TETHYAN OCEANS TECTONIC DOMAINS

Almost all the major continents and microcontinents underwent northward drift during the Phanerozoic, resulting in the gradual breakup of the Gondwana and the southward growth of the Asian continent. The amalgamation of the Asian continent was controlled by two different and successive ocean systems: the Paleo-Asian Ocean and the Tethyan Oceans, which were responsible for the early and late stages of construction of the Asian continent. The initial subduction in the Paleo-Asian Ocean took place at ca. 1.0Ga, long before the earliest Tethys Ocean, however it overlapped with the Paleo-Tethys Ocean during its late stage of tectonic evolution. In contrary to the Tethyan Oceans that were short-lived and internal oceans, the Paleo-Asian Ocean was long-lived with tremendous juvenile continental crust accreted to its margins, forming one of the largest accretionary orogens in the world, the Central Asian Orogenic Belt. The Siberia, Tarim and North China blocks first underwent northward drift during the early Paleozoic, the driving force for the northward drift of them were provided by the subduction of oceanic plates in the Paleo-Asian Ocean tectonic domain. The rifting of Tarim and North China blocks from the Gondwana represented the initial breakup of the Gondwana and coeval birth of the Paleo-Tethys Ocean. This indicates that there was geodynamic link between the Paleo-Asian Ocean and the Tethyan Oceans tectonic domains, which needs to be investigated in the future. There is also some similarity in the drift form of continental blocks between them, for instance, the late Paleozoic northward drift of the Tarim block and the Cretaceous northward drift of the India block, which was the development of passive continental margin on the northern part of both continental blocks, indicating the pull force of the subducting South Tianshan and Neo-Tethys oceanic plates toward the north provided the driving force. This is different from what happened in the eastern Pacific, where the westward drift of the American continents and the opening of the Atlantic Ocean resulted in the development of the Cordilleran accretionary orogens. These indicate that there was geodynamic link between the Paleo-Asian Ocean and the Tethyan Oceans tectonic domains, the successive development of them resulted in the assembly of the current Asian continent.