Abstract

Recently available geological data on Tibet, Yunnan and Burma facilitate recognition of Phanerozoic subduction systems and two continental fragments of Gondwanaland which extend through mainland SE Asia. A Cambrian subduction system and 5 Mesozoic-early Caenozoic collision belts are identified in the region. Indochina, eastern Thailand and Central Tibet accreted to China in the early Triassic; western SE Asia and S Tibet separated from Gondwanaland in the Permian or early Triassic and collided with Asia in the late Triassic, and the western Burma island arc system collided with Asia in the Jurassic. Upper Triassic flysch and schist in the eastern Indoburman Ranges were accreted to western Burma in the Jurassic-early Cretaceous during eastward subduction and formation of a back-arc thrust belt. Following collision of Greater India with arc complexes to the N in the Cretaceous, and with Tibet in the early Eocene, western Burma moved northwards about 450 km along the Sagaing-Namyin ridge-thrust transform fault. Formation of the 3 major belts of tin granites and the porphyry copper deposits in the region took place in specific tectonic settings within the subduction systems and collision belts.

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