Abstract

The observed subsidence in well data and on reflection profiles from the Makassar Basin appears to be compatible with those produced by the simple instantaneous extension of the lithosphere as envisaged by the stretching model of McKenzie (1978). The formation of the basin started with rifting in Lower-Middle Eocene or probably earlier, and continued until the Lower Miocene. Rifting had ceased by the end of Lower Miocene, and since then the sediments have been deposited continuously across the basin without siginificant deformation. Multichannel reflection seismic data from the basin indicate that deposition of the sediments has occurred at a uniform rate while the basin itself was subsiding uniformly, which resulted in deposition of more than 6 km of sediments during the Tertiary.

The stretching model also predicts that oceanic crust will occur at a stretching factor of 2.9, corresponding to a present water depth of not less than 3.2 km. Since such a depth of water does not occur in the basin, it is believed that spreading, - as in the sense of Atlantic-type margins has not yet been developed in the Makassar Basin. The Basin is underlain only by a thinner continental crust compared with the surrounding areas.

With regard to hydrocarbon prospects, it appears that sediments beneath the C2 marker (pre-Lower Miocene sediments) which were deposited at a depth greater than 2.5 km have reached a sufficient temperature for hydrocarbon generation.