Abstract

The Bone Basin is situated between the southwestern volcanic arc and southeastern collision complex of South Sulawesi region. The basin is clearly rimmed by major N-S oriented marginal faults, sub parallel to its axis. The southwestern margin of the basin is bounded by N-S oriented Walanae and West Bone Bay Fault Systems, while the northeastern margin of the basin is bordered by East Bone Fault System. Three main depocentres can be identified in this area. Firstly, the easterly dipping depocentre, known as North Bone Sub-basin, is located in the northern tip of the basin. The other two depocentres are located in the southwestern part of the Basin. One is a westerly dipping half graben system of South Bone Sub-basin, which is bounded in its western margin by the easterly dipping of West Bone Bay Fault System. The other depocentre is located in the southwestern most part of the basin and is typified by an easterly dipping half graben system of the SW Bone Sub-basin. It is bordered on its eastern margin by the westerly dipping Walanae Fault System.

Tertiary sedimentation filling of the Bone Basin was initiated by deposition of the Middle-Late Eocene (or older?) syn-rift deltaic-shallow marine sediment equivalent to the Toraja / Malawa Formation and followed by deposition of the Oligo-Miocene marine carbonate-clastic sediment equivalent to the Tonasa/Makale Formation. The Middle Miocene to Pliocene sediments comprise clastic/volcanoclastic deposits equivalent to the Camba Formation with carbonate deposition in some parts of the basin. The Late Miocene depositional process in this basin was typified by shallow marine carbonate deposition equivalent to the Tacipi Formation, which laterally changes to deep marine sediment and is subsequently followed by development of Late Miocene-Pliocene progradation type sediment equivalent to the Walanae Formation.

The Middle-Late Eocene deltaic-shallow marine syn-rift sediment, deposited within the N-S trending graben system, can act as a potential source rock for hydrocarbons in this basin that reached maturity in Middle-Late Miocene time. The hydrocarbon plays for the Bone Basin comprise: the Middle-Late Eocene tilted fault block play that is formed along the western margin of the basin, including the area of SW Bone Sub-basin, and the faulted anticlinal play that involves deltaic- shallow to deep marine Middle-Late Eocene reservoirs. The other hydrocarbon plays that are developed in this basin include Middle and Late Miocene reefal carbonates that developed along western and northeastern margin of the basin, and a combination lateral pinch-out and tilted fault block play for clastic turbidites that occur along the slope of the basin.