Geological history of the Sibumasu Block in Peninsular Thailand: report of a Geologists’ Association Field Meeting in 2007

It is widely accepted that Thailand consists of two principal blocks or terranes, both of Gondwana origin, which collided and fused in the Late Triassic. The western of the two is the Sibumasu Block, and the purpose of this field meeting was to examine Peninsular Thailand where the succession reveals the nature of Sibumasuʹs Late Palaeozoic rifting from Gondwana in the context of the overall Phanerozoic history of this block. Sedimentary rocks ranging from Cambrian to Miocene crop out in Peninsular Thailand, as well as granite plutons which are aligned in N-S chains, the western chain of Cretaceous–Palaeogene age and those further east of Triassic age. Of particular importance in that history was the NNE-SSW Khlong Marui Fault belt which coincides with the conspicuous bend of the Peninsula; it formed the (present day) eastern boundary of a Late Palaeozoic rift and has been active intermittently since.