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Carbonate Platform Development in Northeast Australia

Peter J. Davies, P. A. Symonds, D. A. Feary, C. J. Pigram

In northeast Australia, the Great Barrier Reef and the Queensland and Marion plateaus comprise carbonate platforms separated by major rift basins. Cenozoic platform evolution has been dependent upon (1) northward drift of Australia from temperate into tropical latitudes; (2) subsidence pulses in the Eocene/Oligocene and the Pliocene/Pleistocene; (3) sea level oscillations; (4) continental and oceanic influences; and (5) paleophysiography and paleo-ocean chemistry. The evolution of each platform reflects the interaction of these factors on its development. Further, the evolution of the Queensland Plateau has markedly affected that of the Great Barrier Reef through its influence on circulation patterns. In the Eocene/Oligocene, the shelf on which the Great Barrier Reef grew protected the Marion Plateau from terrigenous influences, while in the late Miocene to early Pliocene the Marion Plateau formed the "springboard" from which the central and southern Great Barrier Reef developed.

Models of platform development must take account of (1) early Eocene reef initiation on the Queensland Plateau concomitant with marine transgression into the adjacent rift troughs; (2) Eocene/Oligocene subsidence resulting in stepback of the reefs from the flank of the Queensland Plateau and reestablishment at higher bathymetric levels, concomitant clastic sedimentation along the tropical northern continental margin and temperate(?) carbonate progradation along the margin of the Marion Plateau; (3) extensive growth of Miocene reef complexes on the Queensland Plateau and the initiation of reef complexes on the Marion Plateau and on the northern section of the Great Barrier Reef; and (4) Pliocene subsidence leading to contraction of the area of reef growth on the Queensland Plateau, wit almost total "drowning" of the Marion Plateau and stepback of the Miocene barrier and platform reefs to their present position on the central Great Barrier Reef. Post-Pliocene evolution of the Great Barrier Reef is related to sea level change causing low sea level fluvio-deltaic deposition and high sea level reef growth.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.