Within Australia's marine jurisdiction (AMJ) there are at least ten deepwater basins related to Mesozoic rifted margins that have the potential to contribute at least one new petroleum province of global significance. Current offshore exploration activity in Australia is focussed around giant fields in the north west (North West Shelf) and in the south east (Bass Strait) quadrants of the AMJ, representing less than one percent of the prospective acreage. Frontier basins in deepwater along Australia's southern and eastern margins are vastly under-explored with only three exploration wells having been drilled in water depths beyond 500 metres and limited, sometimes only regional, seismic coverage. Despite this minimal exploration, active petroleum systems are indicated by remote sensing techniques (SAR, ALF), seismic evidence of bottom simulating reflectors (BSRs), flat spots and gas escape structures, beach strandings of asphaltites, and oil and gas shows in the few wells in this region. Key prospects for hydrocarbon exploration in the future include the basins of the Great Australian Bight, the west Tasmanian margin and the Lord Howe Rise.
Australia's southern margin is conjugate with Antarctica and was the site of a major Mesozoic rift valley system approximately 4,000 kilometres long. At its eastern end the giant Gippsland Basin fields were discovered in the 1960s, but the western two-thirds of the margin is essentially unexplored. A giant Late Cretaceous delta complex is apparent even on present day bathymetry. It is comparable in area to the Niger Delta, with prograding sequences up to 5,000 metres thick. These sand-rich sequences overlie mobile units representing Albian and Turonian marine shales; and the total sedimentary section is up to 15,000 metres thick.
Along the western margin of Tasmania and on the South Tasman Rise the break-up had a strong transcurrent component producing a series of strike-slip basins up to 6,000 metres thick. Restricted marine environments were maintained along this part of the margin until the final separation of Australia and Antarctica in the Oligocene.
The Lord Howe Rise is a large continental fragment lying between Australia, New Caledonia and New Zealand in the Tasman Sea. It covers an area of 740,000 square kilometres in waters shallower than 3000 metres. It is underlain by a number of sedimentary basins, some in excess of 4,000 metres thick.
BSRs indicative of gas hydrates, flat spots and diapiric features have been observed on the limited seismic coverage.
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Australia's marine jurisdiction covers 14.2 million square kilomet
