The Southeast Asian tin belt

The Southeast Asian Tin Belt is a north-south elongate zone 2800 km long and 400 km wide, extending from Burma (Myanmar) and Thailand to Peninsular Malaysia and the Indonesian Tin Islands. Altogether 9.6 million tonnes of tin, equivalent to 54% of the worldʹs tin production is derived from this region. f the granitoids in the region can be grouped geographically into elongate provinces or belts, based on petrographic and geochronological features. Main Range Granitoid Province in western Peninsular Malaysia, southern Peninsular Thailand and central Thailand is almost entirely made up of biotite granite (184–230 Ma). Tin deposits associated with these granites contributed 55% of the historic tin production of Southeast Asia. Northern Granitoid Province in northern Thailand (0.1% of tin production) also has dominant biotite granite (200–269 Ma) but it is distinguished by abundant post-intrusion deformation. Eastern Granitoid Province extends from eastern Peninsular Malaysia to eastern Thailand. The Malaysian part is subdivided into the East Coast Belt (220–263 Ma), Boundary Range Belt (197–257 Ma) and Central Belt (79–219 Ma). The granitoids cover a wide compositional range from biotite granite to hornblende-biotite granite/granodiorite and diorite-gabbro. Tin deposits are associated with biotite granite in the East Coast Belt (3% of tin production). The granitoids in the other areas of the Eastern Granitoid Province are barren. Western Granitoid Province (22–149 Ma) in northern Peninsular Thailand, western Thailand and Burma has biotite granite and hornblende-biotite granite/granodiorite. Tin deposits are associated with biotite granite, which probably is the dominant phase (14% of tin production). anitoids of the Indonesian Tin Islands (193–251 Ma) do not permit grouping into geographically distinct units. Main Range-type and Eastern Province-type plutons occur next to each other. Most of the tin deposits are associated with Main Range-type plutons (28% of tin production). neralized plutons are characterized by high concentrations of SiO2, K2O, Rb, Sn, Th and U, whereas the concentrations of Fe2O3, MgO, CaO, Na2O, Ba and Sr as well as the Fe2O3FeO ratios are low. Tin-mineralized plutons are also distinguished by high initial 87Sr86Sr ratios low magnetic susceptibilities.