Geodynamics of Southeast Asia in relation to the evolution of ocean basins

Abstract

The Phanerozoic geodynamics of Southeast Asia has been closely connected with the cyclic development of large oceanic basins. These basins were Paleotethys in the Middle Paleozoic to Early Mesozoic, Tethys from the end of the Paleozoic to the beginning of the Cenozoic, and the Indian and Pacific Oceans, together with their marginal seas, in the Late Mesozoic and Cenozoic. The opening of those basins was mainly due to the fragmentation and moving apart of blocks of continental crust, and it was accompanied by the simultaneous closing of other earlier basins and by local accretion and compression of sialic crust. Thus the relative compensation of constructive and destructive processes seems to have existed in Southeast Asia. The most impressive example of such interconnected geodynamics systems was the opening of Tethys (the Indus-Tsangpo Zone, Central Burma, Sumatra) and synchronous closing of Paleotethys (Upper Yangtse, Ailaoshan, North and Central Thailand, the Malay Peninsula) in the Permian-Triassic. The opening of the Indian Ocean and simultaneous closing of Tethys north of it occurred in the same manner from the Late Jurassic till the early Neogene. All events mentioned are clearly recorded in present and ancient continental margins and collision zones. These structures can be studied by applying lateral structural-stratigraphic analysis, which helps in restoring existing and past geodynamics.