Meteor impact crater of biggest extinction ever found, claim researchers
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Last Updated: Monday, August 05, 2013, 19:43
  
Melbourne: Researchers claim to have discovered the elusive impact crater of the meteor that triggered the biggest extinction ever, around 252.3 million years ago.

While the idea that an impact caused the Permian extinction has been around for a while, what's been missing is a suitable crater to confirm it, researchers said.

Researcher Eric Tohver from the University of Western Australia believe he has found the impact crater which reveals though the trigger was the same, the details are significantly different.

Last year Tohver redated an impact structure that straddles the border of the states of Mato Grosso and Goias in Brazil, called the Araguainha crater, to 254.7m years.

Previous estimates had suggested Araguainha was 10m years younger, but Tohver has put it within geological distance of the extinction date.

The Chicxulub crater in Mexico, is 180km in diameter while the Araguainha is 40 kilometres across and was thought to be too small to have caused the chain reaction which brought about such mass extinction.

"We were particularly interested in the Araguainha crater, since the original age determined in the 1990s was relatively close to the Permo-Triassic boundary. The refinements in geochronological techniques that we are applying are helping to reveal the true age of these structures," Tohver said.

The results of an extensive geological survey of the Araguainha crater revealed that a sizable amount of the rock is oil shale, researchers said.

The researchers calculated that the impact would have generated thousands of earthquakes of up to magnitude 9.9, significantly more powerful than the largest recorded by modern seismologists for hundreds of kilometres around, releasing huge amounts of oil and gas from the shattered rock.

Tohver believes the explosion of methane released into the atmosphere would have resulted in instant global warming, making things too hot for much of the planet's animal life.

It's estimated more than 90 per cent of all marine species and about 70 per cent of land-based species disappeared in the Permian extinction, researchers said.

PTI


First Published: Monday, August 05, 2013, 19:39


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