The geology and prospectivity of Buton Island, S.E. Sulawesi, Indonesia
Year: 1991
Proceedings Title : Proc. Indon. Petrol. Assoc., 20th Ann. Conv., 1991
Buton Island is located in Eastern Indonesia, off the southeast coast of Sulawesi. The island's stratigraphy and structural style are distinctly different from S.E. Sulawesi and Muna Island. However, broad similarities are recognized between Buton and adjacent islands in the Banda Arc, specifically Timor, Seram, and Buru.Sedimentation on .Buton was controlled by four tectonic events, a Permian to Late Triassic ",Pre-rift", event, a Late Triassic to Oligocene ",Rift-Drift", event, an Early Miocene to Pliocene ",Syn- and Post-Orogenic", event, and a Recent ",Orogenic", event.",Pre-Rift", sedimentation includes Permian(?) metasediments unconformably overlain by Early Triassic turbidites derived from the Australia- New Guinea continent. Deposition was on the continental shelf, possibly in rift-grabens. ",Rift-Drift", sedimentation was in response to Late Triassic rifting. Middle Jurassic breakup, and Late Jurassic to Oligocene northwestward drift of the Buton microcontinent from the Australia-New Guinea continent. Stratigraphy consists of Late Triassic turbidites, and Jurassic to Oligocene, deep marine calcilutites. ",Syn- and Post-Orogenic", sediments include Early to Middle Miocene coarse clastics, Late Miocene fine clastics, and Pliocene mads / claystones. The coarse clastics were deposited within intra-thrust basins, generated by the Early to Middle Miocene collision of the Buton microcontinent with Muna / S.E. Sulawesi. Pliocene sedimentation coincided with regional subsidence of Buton following accretion of the island to Sulawesi, and an easterly shift of the subduction zone. Quaternary to Recent sedimentation consists of reefal limestones deposited during regional uplift, wrench faulting, and northerly tilting of the island. Deformation was in response to the oblique collision of the Tukang-Besi and Buton microcontinents.The hydrocarbon prospectivity of Buton is considered favorable. Abundant asphalt occurrences, coupled with numerous gas and ",live", oil seeps, confirm that hydrocarbons have been generated. Triassic bituminous shales and limestones are the primary source rocks. Upper Cretaceous, Early to Middle Miocene, and Pliocene clastics and carbonates are potential reservoirs. Primary traps include Miocene thrust and / or Pliocene wrench-related anticlines. Faults are the principal conduits for hydrocarbon migration.
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