Bedout: a possible end-Permian impact crater offshore of northwestern Australia.
The Bedout High, located on the northwestern continental margin of Australia, has emerged as a prime candidate for an end-Permian impact structure. Seismic imaging, gravity data, and the identification of melt rocks and impact breccias from drill cores located on top of Bedout are consistent with the presence of a buried impact crater. The impact breccias contain nearly pure silica glass (SiO2), fractured and shock-melted plagioclases, and spherulitic glass. The distribution of glass and shocked minerals over hundreds of meters of core material implies that a melt sheet is present. Available gravity and seismic data suggest that the Bedout High represents the central uplift of a crater similar in size to Chicxulub. A plagioclase separate from the Lagrange-1 exploration well has an Ar/Ar age of 250.1 +/- 4.5 million years. The location, size, and age of the Bedout crater can account for reported occurrences of impact debris in Permian-Triassic boundary sediments worldwide.
Becker
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Institute for Crustal Studies, Department of Geological Sciences, University of California, Santa Barbara, CA 93106, USA. lbecker@crustal.ucsb.edu
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D001128:Argon; D001315:Australia; D003460:Crystallization; D005843:Geography; D019015:Geologic Sediments; D005898:Glass; D019110:Meteoroids; D008903:Minerals; D011868:Radioisotopes; D012822:Silicon Dioxide
D008903:Minerals; D011868:Radioisotopes; D001128:Argon; D012822:Silicon Dioxide