ABSTRACT: Neogene sedimentary features of the North Makassar Basin, Indonesia

Moss, Steve J.¹, Peter W Baillie², A Edy Hermantoro³, and Suryadi Oemar⁴
(1) Ikoda Pty Ltd, West Perth, Australia
(2) TGS-NOPEC Geophysical Company, West Perth, Australia
(3) MIGAS, Jakarta, Indonesia
(4) Pertamina, Jakarta, Indonesia

The North Makassar Basin, outboard and east of the Kutai Basin of East Kalimantan, is a marginal oceanic basin that opened via Middle Eocene seafloor spreading coupled with the extension and formation of the Kutai Basin to the west. The basin, bounded to the west by Sulawesi, north by the Sankulirang fault zone and to the south by the Adang fault zone, comprises a maximum of seven kilometers of Palaeogene and Neogene sediments overlying oceanic and attenuated continental crust. During Miocene times sedimentation was clastic deep marine with a multiple-sourced mixed mud/sand-rich submarine fan depositional system fed from the palaeo-Mahakam Delta which had commenced eastward progradation in the N5/6 zones, following Late Oligocene uplift in central Borneo. Sediment was fed into the fan system primarily during lowstands of relative sea level and resultant erosion, incision and reworking of the delta plain, delta front and shelf. Depositional elements recognised on seismic data include sheet mounds (basin floor or lowstand fans), complex mounds (slope fan or lowstand wedge), channel-levee complexes, feeder canyons, ponded sand bodies and mass transport complexes. Limited seismic data suggest that clastic sedimentation was sourced primarily from the west and north with virtually no input into the basin from Sulawesi. During the Pliocene and Quaternary, sedimentation over the entire basin was mainly pelagic and fans, where present, are comprised mainly of reworked deepwater sediments.

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