The asteroid that 'changed Earth'
2013-02-15 14:17
Sydney - A strike from a big asteroid more than 300
million years ago left a huge impact zone buried in Australia and changed the
face of the Earth, researchers said on Friday.
"The dust and greenhouse gases released from the
crater, the seismic shock and the initial fireball would have incinerated large
parts of the Earth," said Andrew Glikson, a visiting fellow at the
Australian National University.
The asteroid was bigger than 10km in diameter, while the
impact zone itself was larger than 200km - the third largest impact zone in the
world.
"The greenhouse gases would stay in the atmosphere
for tens of thousands of years," Glikson told Reuters.
The discovery was made after another researcher alerted
Glikson to some unusual mineral deposits in the East Warburton Basin in South
Australia.
Glikson and colleagues analysed quartz grains drawn from
deep beneath the earth's surface in research starting in 2010 and the crater itself
was recently identified, he added.
The strike may have been part of an asteroid impact
cluster which caused an era of mass extinction, wiping out primitive coral
reefs and other species, added Glikson, co-author of a study published in the
journal Tectonophysics.
The impact happened before the dinosaurs, he said.
The announcement of the discovery came just before a
newly discovered asteroid about half the size of a football field was set to
pass some 27 520 km from Earth.
