HR: 08:45h
AN: B31E-04    [Abstracts]
TI: Meteorite Impact at the Bedout High, NW Australian Margin, and Seismic Velocities: is There a Connection?
AU: * Goncharov, A
EM: alexey.goncharov@ga.gov.au
AF: Geoscience Australia, GPO Box 378, Canberra, ACT 2601 Australia
AU: Kennard, J
EM: john.kennard@ga.gov.au
AF: Geoscience Australia, GPO Box 378, Canberra, ACT 2601 Australia
AU: Becker, L
EM: lbecker@crustal.ucsb.edu
AF: University of California Santa Barbara, Institute of Crustal Studies, 1140 Girvetz Hall, Santa Barbara, CA 93106 United States
AB: The Bedout High in the Roebuck Basin at the NW Australian Margin (NWAM) appears to be a good candidate for a massive impact structure associated with the global Permian/Triassic extinction event. On a regional and crustal scale, the NWAM is one of the best studied offshore areas of Australia: ocean-bottom seismograph (OBS) survey supplemented by deep reflection seismic studies in the region has enabled co-interpretation of conventional deep seismic reflection data and accurate seismic velocity models on several transects, including one across the Bedout High. The purpose of this research is to investigate if there is any manifestation of the meteorite impact on a crustal scale, and also on a finer scale of seismic velocity variation in the basement. The impact of the suggested magnitude may have significantly modified the crustal structure in the region. Depth conversion of reflection seismic data indicates that depth to basement at the top of the Bedout High is approximately 3.9 km, and that the High stands more than 4 km above the surrounding sedimentary basins. The basement and crust in the Roebuck Basin have a number of features that distinguish it from other basins at the NWAM. Rapid crustal thinning outboard of the Bedout High and the presence of a thick layer of magmatic underplating in the lower crust are among these features. The meteorite impact may have been one of the possible causes to have triggered upper mantle melting and generation of a voluminous layer of underplated material. On a finer scale, OBS-derived seismic velocity variation along the basement is speculatively interpreted to be consistent with impact-related effects. However, existing seismic and potential field data do not allow accurate estimates of the extent of the crust affected by the meteorite impact, and effects that it may have had on the subsequent rifting, thermal, sedimentation and hydrocarbon maturation regimes in the area. Further multidisciplinary research is necessary to answer these questions.
DE: 0935 Seismic methods (3025)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting