The Tin Metallogenic Provinces of S.E. Asia and China: A Gondwanaland Inheritance

Abstract

Southeast Asia is interpreted as a composite of stable continental blocks which rifted from the northern margin of Australia and drifted northwards. The intervening highly deformed mobile and suture belts are the remains of the Paleotethys ocean when the blocks collided. The first blocks coalesced to form a Cathaysian East Asian Continent which occupied equatorial latitudes in the Permian. Other blocks rifted later from Australia and collided in Mesozoic and Cenozoic times with the East Asian continent to form the Eurasian Plate.

The tin was carried in the continental infrastructure of these blocks, which are all of Gondwanaland ancestry. Tectonic events which have the greatest continental crustal involvement are the most important in mobilizing tin into economic concentrations.

The foremost tin metallogenic event is a Malayan-type collision between two continental blocks, resulting in crustal thickening and S-type granite batholiths. Any subsequent igneous event superimposed on a Malayan-type belt will also have the ability to mobilize tin. The two important Malayan-type tin belts are (a) the Mesozoic belt formed by the colusión of Sinoburmalaya, the Burma Plate, the Qantang-Tangla, and the Lhasa-Gandise blocks with the East Asian Continent, (b) the Caledonian East China belt.

Pre-rift thermal reworking of continental crust produces roughly concentric areas of subalkaline anorogenic granite with a high potential for tin mobilization, commonly with a tantalum-niobium association. The most important areas are centred in South China — North Vietnam, with isolated examples in Peninsular Malaysia.