Tectonic settings for emplacement of Southeast Asian tin granites

Most tin-bearing granitic rocks in Southeast Asia occur in one of three main belts: an eastern belt largely of Late Carboniferous to Early Triassic age, a central belt with abundant Late Triassic granites, and a western belt with widespread Cretaceous to Early Eocene plutons. From the Palaeozoic to Early Triassic four main stratigraphic-structural zones are recognised: the Shan States-Northwest Thailand-Peninsular Burma and Thailand-Western Malaya (Zone 1)the Eastern Foothills of Malaya (Zone 2)medial Malaya and central Thailand (Zone 3) and eastern Malaya and east central Thailand (Zone 4). Lithology and deformation of these Zones indicates that the eastern belt of tin-bearing granites was emplaced in continental crust of Zone 4 above an eastward-dipping Benioff zonethere is little evidence of either a pre-Carboniferous concentration of metal in the crust, or of remobilisation of metal in the older mineraIised granites by the younger granites