Australasian Science: Australia's authority on science since 1938

Small Crater Responsible for the Great Dying

By Stephen Luntz

An Australian scientist believes he has identified the crater responsible for the greatest extinction in our planet’s history.

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The crater was once considered far too small to have caused the event known as The Great Dying, but a new angle suggests that its formation might indeed have been the cause.

The Chicxulub crater in Mexico is thought to have been formed by the asteroid that wiped out the dinosaurs. However, one-quarter of the animal and plant species alive during the Cretaceous survived that event.

Since Chicxulub is 180 km across it was thought that the object responsible for the Permian–Triassic (P-Tr) extinction event 187 million years earlier must have been even larger. The P-Tr event wiped 96% of marine species from the fossil record, and marks the only known mass extinction of insects.

The Araguainha crater in Brazil is 40 km across, making it an unlikely cause for such a large extinction. Moreover, previous estimates of its age put it 8 million years after the P-Tr extinction event.

However, Dr Eric Tohver of the University of Western Australia’s School of Earth and Environment has been working with fellow WA-based researchers Martin Schmieder and Fred Jourdan to improve the dating of impact structures around the world (AS, October 2013, pp.16–20). “We were particularly interested in the Araguainha crater, since the original age determined in the 1990s was relatively close to the Permo-Triassic boundary,” says Tohver. “The refinements in geochronological...

The full text of this article can be purchased from Informit.