ABSTRACT: Structure and Collision History of the Buton Continental Fragment, Eastern Indonesia

MILSOM, JOHN, University College, London, United Kingdom

Although often reservoired within Tertiary rocks, the known hydrocarbons of eastern Indonesia are widely believed to be source from sediments deposited as part of the Mesozoic succession of the Australian continental margin. Fragments of this margin are now widely dispersed as allochthonous terranes throughout eastern Indonesia, one of the most far traveled examples being exposed on the island of Buton, southeast of Sulawesi. Asphalt reserves on Buton support a significant local industry and exploration continues for oil and natural gas. In common with other prospective Australian margin terranes, Buton is now separated from Australia by the active plate boundary marked by the Sunda and Banda arcs. Determinations of the subsurface limits of the Buton Terrane and reconstructions of its evolutionary history have an important role to play in guiding future exploration.

Geophysical studies of the Buton region have utilized gravity, magnetic and seismic reflection techniques. On the basis of these data it would seem that there have been significant relative rotations within the Buton terrane and that it has minor extensions beneath the adjacent island of Muna. However, the Tukang Besi platform, which lies to the east of Buton, appears to be a distinct, and possibly unrelated, unit.

Ophiolitic rocks exposed on Buton do not seem to be attached to deep roots and have probably been transported with the terrane as thin overthrust sheets. They therefore do not mark a terrane boundary and their presence has little effect on the prospectivity of the region.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)