Gondwana Dispersion & Asian Accretion: An update

East & Southeast Asia comprises a collage of continental terranes derived directly or indirectly from the India-Austra-lian margin of eastern Gondwana (Figures 1 and 2 below). The Late Palaeozoic and Mesozoic evolution of the region involved the rifting and separation of three elongate continental slivers or collages of terranes from eastern Gondwana and the successive opening and closure of three ocean basins, the Palaeo-Tethys, Meso-Tethys and Ceno-Tethys. Recent work in mainland SE Asia (Thailand, Sumatra and Burma in particular) has led to reinterpretation of some tec-tonic units and their origins and palaeogeographic positions in the Palaeozoic and Mesozoic. The Sukhothai Island Arc System, including the Linchang, Sukhothai and Chanthaburi terranes is identified between the Sibumasu and Indochina-East Malaya terranes in Thailand (Sone & Metcalfe, 2008) and possibly extends into Peninsular Malaysia beneath the Central Belt of the Malay Peninsula (Metcalfe, in press) and was formed by back-arc spreading in the Permian. The Jinghong, Nan-Uttaradit and Sra Kaeo sutures represent this closed back arc basin. The Palaeo-Tethys is represented to the west by the Changning-Menglian, Chiang Mai/Inthanon and Bentong-Raub suture zones. The Cenozoic Mai Yuam Fault does not represent the trace of the Palaeo-Tethys as suggested by some authors (e.g. Ueno & Hisada 2001; Ueno 2003; Ferrari et al. 2008). The concept, definition and recent contradictory application of the term “Shan-Thai ” to tectonic units in the region has caused unnecessary confusion and recent usage of this term fo