ABSTRACT: Exploration of the Banda Orogen, Indonesia
R. A. Harris, M. G. Audley-Charles, S. L. Tobing
An integrated geologic evaluation of the late Miocene to present Banda orogen and its petroleum potential is in progress. The focus of the investigation involves sedimentary sections of the NW Australian continental margin incorporated into the Banda orogen.
The islands of Timor and Seram, and several other islands throughout the Banda orogenic arc, are the closest exposed lithostratigraphic equivalents of the hydrocarbon producing NW Australian subsurface stratigraphy. Hydrocarbon occurrences are well documented on many of the islands, and over 13 million barrels of oil have been produced from the Bula field in Seram.
Recent studies of seeps in Timor and associated stratigraphic, structural, and geochemical relations indicate that (1) oil and gas seeps occur throughout the Permian to Pliocene stratigraphic section; (2) bituminous limestones of the Triassic Aituti Formation are the most likely source for many of the seeps; (3) preliminary geochemical analyses of the oils indicate a mixed terrestrial and marine organic source, and suggest a genetic link between the Aitutu oils and oils seeping from Tertiary reservoirs; (4) triterpane and sterane parameters indicate some of these oils are highly mature; (5) palynomorph coloration, conodont alteration, and clay mineralogy data yield paleotemperature estimates in the range of hydrocarbon generation from much of the pre-rift sequence (Permian-Jurassic); 6) structural modeling suggests that the initial decollement zone of the orogenic wedge formed near the Jurassic breakup unconformity of the underthrust NW Australian margin, imbricating the post-rift sequence; (7) in Timor and Seram the decollement has stepped to deeper levels involving pre-rift sequences that form structural culminations in the core of the orogen. The culminations are expressed as topographic highs as in New Guinea and Oman.
AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990