Publications

An evaluation of regional Neogene sedimentation rates across the Sunda region, together with improved regional palaeoenvironment mapping, has permitted comparison of the major delta and fan depositional systems across the region. This has enabled a reassessment of the palaeogeography of the area through the positioning of the main river systems and from establishing the timing of uplift of uplands based on sudden increases in regional sedimentation rates. The palaeo-altitude of upland areas has been established from the record of pollen characteristic of plants restricted to montane forests. This evaluation shows major differences in sedimentation patterns, especially between the Makassar Straits and offshore Sarawak, despite these areas containing similar thicknesses of Neogene sediment. During the Middle Miocene, the bulk of sedimentation across the Sunda region took place on a greatly enlarged Proto-Mahakam Delta, with minimal sedimentation offshore Sarawak. By contrast, during the Late Miocene, sedimentation rates increased dramatically offshore Sarawak and there was a sharp reduction in sedimentation within the Makassar Straits. This is interpreted to reflect redirection of sediment transport as a result of Borneo uplift and capture of the Proto Mahakam River by Sarawak rivers during the Late Miocene. This evaluation also clarifies the timing of uplift and denudation of uplands across the region from Thailand the Sunda Shelf, Borneo Sumatra, and Sulawesi.