ABSTRACT: Gravity field and structure of the crust beneath the Makassar Strait, Central Indonesia

Sardjono , Geological Research and Development Centre, Bandung, Indonesia

The region of the Makassar Strait has been identified as a major geological feature and is considered to be highly potential for hydrocarbon exploration. Despite extensive investigation, carried out mostly commercially, the present geoscientific knowledge about this region is not yet well established. The region is situated between two major terrane provinces, i.e. terranes with the Eurasian affinity on the west and Australian affinity on the east. Basement of the Makassar Strait comprises highly attenuated continental crustal rocks and probably also parts of upper mantle materials. Basins with sediment thickness of up to about 15,000 metres and water depth within the range of 2,000-3,000 metres suggest complex tectonic processes related to the formation of the sedimentary basins in the region.

SEASAT-derived potential data defined the free-air gravity field of the Makassar Strait. Results of processing, enhancement and analyses of the gravity field demonstrate delineation of structural trends as well as structure of the crust beneath the water of the Makassar Strait. Results also indicate that the development of sedimentary basins in the Makassar Strait involved regional stretching of the continental crust which started in the Miocene or earlier but tectonic polarity changed, probably started from Late Miocene. Geometry of the crustal models indicates buckle-up of the lower crustal rocks, suggesting that regional stretching had ceased and regional compression has been prevailing until the present day.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia