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ABSTRACT: The Geology and Petroleum Potential of the Arafura Sea

Jeanette M. McLennan, John S. Rasidi, Richard L. Holmes, Greg C. Smith

The northern Bonaparte basin and the Arafura-Money Shoal basins lie along Australia's offshore northern margin. Although adjacent, they offer significantly different exploration prospects resulting from their opposing tectonic and burial histories. The Arafura basin is dominated by a deep, faulted and folded, NW-SE-oriented graben. Basin-fill is mainly Paleozoic on Precambrian basement. Major emergence and erosion in the Triassic-Jurassic preceded the development of the Money Shoal basin, which records only moderate subsidence and sedimentation with subtle structuring. In the northeastern Bonaparte basin, significant extension of Precambrian basement did not occur until the Mesozoic, resulting in the development of the deep NE-SW-oriented Malita graben with mainly Jurassi to Recent basin-fill.

A variety of potential structural and stratigraphic traps occur in the region, especially associated with the grabens. They include tilted or horst fault blocks and large compressional, drape, and rollover anticlines. Some inversion and possibly interference anticlines result from late Cenozoic collision of the Australian plate with Timor and the Pacific Plate.

In the Arafura-Money Shoal basins, good petroleum source rocks occur in the Cambrian, Carboniferous, and Jurassic-Cretaceous sequences although maturation is biased towards early graben development. Reservoir quality decreases with depth: The Jurassic-Neocomian sandstones have the best potential, Carboniferous clastics offer moderate prospects, and the lower Paleozoic carbonates require porosity enhancement.

The Malita graben probably contains good potential Jurassic source rocks that commenced generation in the Late Cretaceous, Deep burial in the graben has decreased porosity of the Jurassic-Neocomian sandstones significantly but potential reservoirs may occur on the shallower flanks.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990