ABSTRACT: Frontier Petroleum Basins off Eastern Australia

P. A. Symonds, J. B. Willcox, J. B. Colwell, D. A. Falvey

The passive continental margin of eastern Australia extends for a distance of 5000 km from the Gulf of Papua in the north to the southern end of the South Tasman Rise. Apart from the highly productive Gippsland basin, which accounts for about 90% of Australia's oil production, the margin is virtually unexplored. The margin is the result of a Cretaceous rift phase followed by breakup and sea-floor spreading, which commenced in the Late Cretaceous in the south, in the Paleocene in the north, and ceased along the length of the system during the early Eocene. Variations in the style and geometry of extension have produced a complex arrangement of marginal plateaus and rift troughs in the northeast and a narrow, largely basin-free margin in the southeast, where much of the rif system was detached from Australia and now lies on the western Lord Howe Rise.

Recent research programs by the Bureau of Mineral Resources have confirmed that large sedimentary basins, some of considerable thickness and structural complexity, occur in deep water (200-2000 m) beyond the frontier of conventional offshore exploration activity along the eastern Australian margin and its conjugate. The most prospective areas are adjacent to the Gulf of Papua in a distal foreland basin setting and in rift-related depocenters in the Queensland and Townsville Troughs, beneath the western flank of Lord Howe Rise, in the deep-water part of the Gippsland basin and beneath the flanks of the South Tasman Rise.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990