ABSTRACT: Absolute Amplitude of Neogene Sea Level from Carbonate Platforms of the Marion Plateau, Northeast Australia

C. J. Pigram, P. J. Davies, P. A. Symonds, P. A. Feary, G. Chaproniere

The Marion Plateau sequence off northeastern Australia is a shallow-water early Miocene to Holocene carbonate platform that consists of four growth phases (early Miocene, late Miocene-early Pliocene, late Pliocene-Pleistocene, and Recent) age separated by subaerial unconformities. Each unconformity is a record of the high sealevel stand. The late Miocene to Pliocene growth phase is a lowstand shallow water platform initiated on the slope deposits of the preceding early Miocene growth phase. The difference between the top of the oldest phase of shallow-water growth and the youngest shallow-water deposits of the second phase record precisely to a middle to early late Miocene sea level fall. After backstripping and correction for the effects of subsidence, compaction, and paleowater dept , a conservative estimate of 150-200 m is obtained for the absolute amplitude of this composite sea level fall. Because it is possible to constrain these factors with this method, one can avoids the uncertainties associated with estimating the amplitude of sea level fluctuations derived from other environments and use other methods such as atolls, isotopes, and siliciclastic passive margins systems.

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