Transitional I S type characteristic in the Main Range Granite, Peninsular Malaysia

Abstract

The dominantly Triassic Main Range Granite of Peninsular Malaysia that occurs west of the Paleo-Tethyan Bentong–Raub suture zone was regarded exclusively as an S-type granite. The Main Range dominantly biotite granites are of batholithic proportion and host one of the world’s largest tin provinces. The S-type characteristics include high initial 87Sr/86Sr isotope ratios (>0.710), a narrow range in silica, presence of ilmenite and occasional cordierite and andalusite, and the presence of pelitic or quartzose meta-sedimentary xenoliths. However, the present review shows that the Main Range Granites also have many features that are more characteristic of I-type granites such as the very large scale of plutonism, the presence of primary titanite and amphibole, occurrence of hornblende-bearing mafic enclaves, increasing peraluminosity towards the more differentiated end-members of the suite and decreasing P2O5 with increasing SiO2 contents. The moderately peraluminous nature of the bulk Main Range Granite, without containing cordierite, Fe–Mg garnet or sillimanite, is consistent with derivation from a meta-sedimentary protolith that was itself undersaturated with respect to Al2SiO5.