Bedout

For the French Navy officer, see Jacques Bedout

Bedout /bᵻˈduː/, or more specifically the Bedout High, is a geological and geophysical feature centered about 250 km off the northwestern coast of Australia in the Canning and overlying Roebuck basins. Although not obvious from sea floor topography, it is a roughly circular area about 30 km in diameter where older rocks have been uplifted as much as 4 km towards the surface. The Bedout High was penetrated by two petroleum exploration wells (Bedout-1, Lagrange-1) in the 1970s and 1980s. It is named after nearby Bedout Island.

Impact hypothesis

In 1996 Australian geologist John Gorter first suggested that the Bedout High might mark the centre of a very large buried impact crater up to 250 km in diameter, based mainly on its internal geological structure as revealed on a single seismic survey line, and suggested that it may be of near end Permian age, based on the reported age of volcanic rocks in Lagrange-1. The impact hypothesis was developed further by Luanne Becker (University of California) and coworkers who claimed to have confirmed that the supposed volcanic rocks in the petroleum wells are actually impact melt breccia showing evidence of shock metamorphism, and re-dated these rocks at 250.1 ± 4.5 Ma. The new age is essentially coincident with the Permian-Triassic boundary and associated extinction event, and Becker speculates that there is a likely connection. It was subsequently reported, based on very limited preliminary data, that the impact hypothesis is further supported by chromium isotope evidence for the presence of extraterrestrial material.