GONDWANALAND DISPERSION, ASIAN ACCRETION AND EVOLUTION OF EASTERN TETHYS

Most east and southeast Asian continental blocks, comprising North and South China, Indochina (including the Qamdo-Simao Block), Tarim (incl uding the Kunlun and Ala Shan Terranes), Qaidam, Sibumasu, Qiangtang, Lhasa, Kurosegawa, Northwest and Southeast Hainan, West Burma and Woyl a Terranes, had their origins on the northern margin of Gondwanaland. Phanerozoic evolution of ea:stern Gondwanaland and Tethys involved the successive rifting and separation of three continental slivers (now r ecognised as collages of terranes) from northern Gondwanaland, their n orthwards drift, and amalgamation/accretion to form east and southeast Asia, These continental slivers separated from the margin of Gondwana land in the Late Devonian (North China, South China, Indochina, Qaidam , Tarim and Hainan Island Terranes), Early-mid-Permian (the Cimmerian continent including the Sibumasu and Qiangtang Terranes), and Late Tri assic-Late Jurassic (Lhasa, West Burma and Woyla Terranes). The northw ards drift of these terranes was accompanied by the opening and closin g of three successive oceans, the Palaeo-Tethys, Meso-Tethys and Ceno- Tethys. Assembly of Gondwanaland-derived Asian terranes began with the amalgamation of South China and Indochina during the Early Carbonifer ous along the Song Ma Suture to form 'Cathaysialand'. Cathaysialand an d North China formed large continental regions at low northern/equator ial latitudes within the Palaeo-Tethys during the Late Carboniferous a nd Permian. The Tarim, Kunlun, Qaidam and Ala Shan Terranes accreted t o Kazakstan/Siberia in the Permian. Separation and northward drifting of the Cimmerian continent from northeast Gondwanaland in the late Ear ly Permian was accompanied by the opening of the Meso-Tethys. This was followed by the suturing of Sibumasu and Qiangtang to Cathaysialand i n the Late Permian-Early Triassic, largely closing the Palaeo-Tethys. North and South China amalgamated in the Permian-Triassic and accreted to Laurasia in the Late Triassic-Early Jurassic. The Lhasa, West Burm a and Woyla Terranes separated from northwest Australian Gondwanaland during the Late Triassic to Early Cretaceous as the Ceno-Tethys opened and the Meso-Tethys was destroyed by subduction beneath Eurasia. Thes e terranes accreted to proto-southeast Asia in the Early to Late Creta ceous.