The granites which make up the Western Province are of S- and I-type, and although they were thought all to be of Cretaceous age that age bracket has now been expanded, in part because many previously determined ages (e.g. Charusiri et al., 1993) were based on mica Ar–Ar cooling spectra. U–Pb zircon ages of 212 2 Ma and 214 2 Ma (both Late Triassic) have been obtained from an I-type granite from Phuket in Thailand, albeit with zircon rims showing a Late Cretaceous thermal overprint of 81.2 1.2 and 85–75 Ma (Searle et al., 2012).