--> ABSTRACT: Seismic Stratigraphy in the Gulf of Carpentaria, Northern Australia, by N. Terence Edgar, Muriel S. Grim, Blaine C. Cecil, John Chappell; #91020 (1995).

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Seismic Stratigraphy in the Gulf of Carpentaria, Northern Australia

N. Terence Edgar, Muriel S. Grim, Blaine C. Cecil, John Chappell

The 900- by 600-km Gulf of Carpentaria is a shallow epicontinental sea that lies between northern Australia and New Guinea and is a good modern analogue for assessing the application of systems track analysis to siliciclastic sedimentation in epicontinental seas. The gulf, with a maximum water depth of about 70 m and a bottom gradient of less than 1:16,000 in some areas, contains sediments that appear to record numerous sea-level changes. A high-resolution seismic survey conducted by the U.S. Geological Survey and the Australian National University recorded reflections from the upper 100-to 150 m of the sedimentary section. Numerous reflections on these records are interpreted as low-stand exposure surfaces with coeval channels, some of which cut as deep as 80 m into pree isting strata. Low sedimentation rates, numerous Type-1 sequence boundaries, and low seafloor gradients result in sequences less than 10 m thick. Many of the marine depositional features associated with lowstands of sea level are missing in many sequences because the gulf was totally dry during low stands when sea level dropped more than 70 m. The parasequences and parasequence sets extend over large areas because transgressions and regressions ranged over hundreds of kilometers. Because of this geometry and numerous discontinuous reflections, seismic stratigraphy of anticipated sedimentary deposits accumulated in shallow epicontinental seas may be difficult to interpret.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995