ABSTRACT: Tectonostratigraphy of the eastern part of Sulawesi, Indonesia
Surono, Dr. , Geological Research and Development Centre, Bandung, Indonesia
In latest Oligocene-Middle Miocene an oblique collision, younger to the north, took place between the oceanic crust and an Australian continental fragment. Because of the collision, oceanic crust was thrust eastwards over the continental fragment, and the continental fragment was broken into smaller fragments (e.g. Banggai-Sula, Siombok, Tambayoli, Bungku Matarombeo, Southeast Sulawesi and Buton terranes). The oceanic terranes consist mostly of ultrabasic rocks, overlain by pelagic sediments.
The oldest rocks in the Banggai-Sula terrane are metamorphic, thinly overlain by volcanic rocks. The age of the metamorphic rocks is unknown. However, dating of the volcanics shows a Permo-Triassic age, and both metamorphics and volcanics are intruded by granitic rocks of Permo-Triassic age. These units are present as a basement to a Mesozoic basin, in which Upper Triassic shallow-marine carbonates were deposited. The carbonates were unconformably overlain successively by Jurassic clastic sediments and Cretaceous deep-sea carbonates. In turn, the Cretaceous deep-sea carbonates are overlain unconformably by Paleogene carbonate.
A similar stratigraphic sequence exists in the Southeast Sulawesi terrane where a basement, consisting of metamorphic rocks, granitic intrusions and thin volcanic rocks, underlies Upper Triassic fluviatile-marine sediments. The youngest lithologic unit in the terrane is Paleogene carbonate. It is likely that a similar stratigraphic succession is present in the other continental terranes, such as the Siombok, Tambayoli, Bungku and Matarombeo terranes.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia