Abstract

The history and development of the peri-Borneo basins are controlled by major regional tectonic events. Tectonism has also had an important effect on geomorphology and hydrology of the Neogene delta systems around the periphery of the island. These systems formed as a result of the ability to accommodate massive amounts of sediment that became available due to Neogene uplift.

In gross geometry, the deltas are broadly similar, characterised by an inner onshore deformed zone, the modern delta and shallow shelf, a zone dominated by growth faults which may extend down the delta slope and an deepwater outer zone of folding and associated thrust faults.

From the Oligocene the geological evolution has been the result of two opposing forces; the opening of the South China Sea which commenced in the Oligocene and westerly-directed compression as micro-continental material initially sourced from the Australian Plate ("Australoid material") moved westwards since the Miocene. Overall sinistral wrenching has produced zones of deformation extending through Borneo that are the loci of the Neogene delta systems. In western Sulawesi, Neogene compression produced the West Sulawesi Fold Belt.