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Surveys across the western Coral Sea Basin during 1978 and 1980-81 by the Federal Institute for Geosciences and Natural Resources, F.R. Germany, in cooperation with the Australian Bureau of Mineral Resources, have provided new information on the change from continental to oceanic crust in this area.
The opposing margins of the Queensland and Papuan Plateaus are underlain by part of a complex rift zone which would have been up to 50 mi (80 km) wide prior to continental break up. Marginal or "outer" basement highs, which appear to have low angle contacts with the oceanic crust, occur in the oceanward part of the rift zone on both sides of the Coral Sea Basin. Similar highs also occur beneath the lower slope of the Eastern Plateau and within the northern Queensland Trough and the Osprey Embayment. The origin of these highs--listrically faulted and rotated continental blocks, late-stage uplifts of pre-rift rocks, or massive accumulations of volcanic rocks--and its consequences for the deposition and nature of the rift phase sediments are discussed.
The northern Queensland Trough and the western margin of the Eastern Plateau are considered to have the best petroleum potential in the region, in that they are underlain by grabens containing up to 3.1 mi (5 km) of sediments, part of which may be a Mesozoic deltaic sequence similar to that intersected in the Anchor Cay 1 well, or a deeper water equivalent. As these depocenters generally lie in water depths greater than 6,500 ft (2,000 m), they can probably only be considered as long-term prospects. Gently folded ?Mesozoic sediments beneath the eastern margin of the Eastern Plateau, in water depths of just over 4,900 ft (1,500 m), may also have some petroleum potential.
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