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Originally published in Science Express on 13 May 2004
Science 4 June 2004:
Vol. 304. no. 5676, pp. 1469 - 1476
DOI: 10.1126/science.1093925
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Research Articles

Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia

L. Becker,1* R. J. Poreda,2 A. R. Basu,2 K. O. Pope,3 T. M. Harrison,4 C. Nicholson,1 R. Iasky5

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.

1 Institute for Crustal Studies, Department of Geological Sciences, University of California, Santa Barbara, CA 93106, USA.
2 Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, USA.
3 Geo Eco Arc Research, Aquasco, MD 20608.
4 Australian National University, Canberra, Australia.
5 Geological Survey Western Australia, Perth, Australia.

* To whom correspondence should be addressed. E-mail: lbecker{at}crustal.ucsb.edu. Web page: http://beckeraustralia.ucsb.edu

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