Publications

Continuing consumption of crustal material within the collision areas of South East Asia destroys critical geohistorical evidence. What remains is a patchwork quilt of incomplete and frequently contradictory evidence, from which we must deduce the four dimensional truth. This poster reviews the published work on the area and adds further insights concerning the Paleogene growth and eventual demise of the Celebes Sea spreading centre.The Celebes Sea (Fig. 1) located in Indonesian and Philippine territorial waters, is a Paleogene spreading centre which was active until about 37Ma, coincidentally at the same time as the Sarawak Orogeny (Hutchinson 1996). It is an area of deep water with a very narrow marginal shelf. This extensional feature is responsible for much of the Paleogene tectonism of the region, apparently more so than the effects of extrusion tectonics (Tapponnier et al, 1982), but the evidence for its activities is being progressively destroyed by more modern events. The extension approximates the entire length of the Makassar Straits separating the old, stable craton of Kalimantan from the young and active continental fragments within Sulawesi. The southern limit of extension is considered to be the Masalima Trough, leading into the North East Java Sea. The southern limit of its effects may well stretch as far south as the Sumba Fracture (Audley Charles, 1975). The northern limits of its effects are the Cotabato and Negros Trenches where subduction under the western edge of the Philippine Plate is active.The Makassar Straits are a depocentre for material eroded from the Kalimantan mountains, and this is the principal factor in the areas Neogene hydrocarbon prospectivity. However, there are also hydrocarbon source and reservoir rocks of Paleogene age recognised in the area, particularly South west Sulawesi. This poster examines some of the Paleogene processes responsible for those rocks, and it attempts to integrate new ideas with the previously published data and interpretations. This poster does not address Neogene processes beyond those critical to Paleogene understandings.