Abstract: Integrated Sequence Stratigraphic Analysis: An Example from the Mesozoic/Cenozoic of Australia

Malcolm I. Ross, Peter Vail

Sedimentation patterns in a basin are controlled by the complex interaction of tectonics, eustacy, sediment supply, and climate. We have taken an integrated approach to understanding the relative tectonic and eustatic signatures seen in the Mesozoic/Cenozoic transgressive and regressive cycles of Australia. A detailed plate tectonic model for the circum-Australian region has been constructed and tied to the global tectonic model of Scotese et al (1992). This model constrains the timing and location of basin subsidence and regional structural styles. These tectonic events are shown to be synchronous with the onset of major transgressive-regressive facies cycle wedges in the Exmouth Plateau, Otway, and Gippsland basins. Total tectonic subsidence plots (Sawyer, 1985) have been made for e ch region to tie the transgressive and regressive cycles to the tectonics events. A detailed analysis of structural deformation timing and styles has been carried out to distinguish, identify, and classify structurally induced local stratigraphic effects.

An independent and internally consistent sequence stratigraphic interpretation for Australia has been constructed based solely on the physical and/or seismic stratigraphic expression of facies progressions. The Exmouth Plateau was used to constrain the Early Mesozoic, the Otway basin the late Mesozoic and the Gippsland the Tertiary (after Rahmanian, 1990). High resolution palynology by Morgan (unpublished) was used and placed in the zonal context provided by Helby, Morgan, and Partridge (1987), providing an internally consistent age-control scheme. Two Ocean Drilling Program (ODP) sites on the outer Exmouth Plateau provide ties to the global timescale (Brenner, 1992, Bralower and Siesser, 1992; Jones and Wonders, 1992). This sequence stratigraphic interpretation has been compared that of Jacquin et al (this meeting). Preliminary results indicated excellent agreement (within the resolution of the age-control scheme).

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994