GONDWANALAND ORIGIN, DISPERSION, AND ACCRETION OF EAST AND SOUTHEAST-ASIAN CONTINENTAL TERRANES

East and Southeast Asia is a complex assembly of allochthonous contine ntal terranes, island arcs, accretionary complexes and small ocean bas ins. The boundaries between continental terranes are marked by major f ault zones or by, sutures recognized by the presence of ophiolites, me langes and accretionary complexes. Stratigraphical, sedimentological, paleobiogeographical and paleomagnetic data suggest that all of the Ea st and Southeast Asian continental terranes were derived directly or i ndirectly from the Iran-Himalaya-Australia margin of Gondwanaland. The evolution of the terranes is one of rifting from Gondwanaland, northw ards drift and amalgamation/accretion to form present day East Asia. T hree continental slivers were rifted from the northeast margin of Gond wanaland in the Silurian-Early Devonian (North China, South China, Ind ochina/East Malaya, Qamdo-Simao and Tarim terranes), Early-Middle Perm ian (Sibumasu, Lhasa and Qiangtang terranes) and Late Jurassic (West B urma terrane, Woyla terranes). The northwards drift of these terranes was effected by the opening and closing of three successive Tethys oce ans, the Paleo-Tethys, Meso-Tethys and Ceno-Tethys. Terrane assembly t ook place between the Late Paleozoic and Cenozoic, but the precise tim ings of amalgamation and accretion are still contentious. Amalgamation of South China and Indochina/East Malaya occurred during the Early Ca rboniferous along the Song Ma Suture to form ''Cathaysialand''. Cathay sialand, together with North China, formed a large continental region within the Paleotethys during the Late Carboniferous and Permian. Pale omagnetic data indicate that this continental region was in equatorial to low northern paleolatitudes which is consistent with the tropical Cathaysian flora developed on these terranes. The Tarim terrane (toget her with the Kunlun, Qaidam and Ala Shan terranes) accreted to Kazakhs tan/Siberia in the Permian. This was followed by the suturing of Sibum asu and Qiangtang to Cathaysialand in the Late Permian-Early Triassic, largely closing the Paleo-Tethys. North and South China were amalgama ted in the Late Triassic-Early Jurassic and finally welded to Laurasia around the same time. The Lhasa terrane accreted to the Sibumasu-Qian gtang terrane in the Late Jurassic and the Kurosegawa terrane of Japan , interpreted to be derived from Australian Gondwanaland, accreted to Japanese Eurasia, also in the Late Jurassic. The West Burma and Woyla terranes drifted northwards during the Late Jurassic and Early Cretace ous as the Ceno-Tethys opened and the Meso-Tethys was destroyed by sub duction beneath Eurasia and were accreted to proto-Southeast Asia in t he Early to Late Cretaceous. The Southwest Borneo and Semitau terranes amalgamated to each other and accreted to Indochina/East Malaya in th e Late Cretaceous and the Hainanese terranes probably accreted to Sout h China sometime in the Cretaceous.