Rift-, Subduction- and Collision-Related Tin Belts

Abstract

Abstract: Consideration of the tectonic setting in which Cenozoic and Late Mesozoic tin-bearing granites were emplaced indicates that subduction-related settings include not only continental margin magmatic arcs (inner zone of southwest Japan, Cretaceous; Aleutian arc, Miocene) but also outer arcs adjacent to the trench (outer zone of southwest Japan, Miocene) and back-arc magmatic belts (Bolivia, Tertiary, and Western Belt of Southeast Asia, Cretaceous-Eocene). The only well-documented post-Palaeozoic example of significant tin mineralisation in a rift or hot-spot related setting is the Jurassic belt of Nigeria. Recent descriptions of tin and associated metals from the Himalaya granites with radiometric evidence of an Oligocene age of emplacement indicates the importance of continental collision as a setting for generation of tin-bearing granites. Possible ancient examples of collision-related tin belts are the Main Range Malaysia, southwest England and the Erzgebirge. There are significant differences among the plutonic rocks, host rocks, adjacent major structural belts and in some cases styles of mineralisation in the various types of tectonic setting which facilitate their recognition. Most tin is apparently derived from trace amounts in the crust and there is little evidence for the presence of primitive concentrations of the metal in the crust or upper mantle.