400km meteorite crater discovered in Australia

SYDNEY: An ancient meteorite crater 400km wide – the largest yet discovered – has been found in central Australia, scientists said on Monday.

The meteorite broke into two pieces shortly before impact, according to Andrew Glikson from the Australian National University, who led research published in the journal Tectonophysics.

“There are two huge deep domes in the crust, formed by the Earth’s crust rebounding after the huge impacts, and bringing up rock from the mantle below,” Glikson said.

Both asteroids may have more been than 10km wide, and hit an area called the Warburton Basin, near the borders of South Australia, Queensland and the Northern Territory.

The meteorite slammed into Earth so long ago that the crater has since been covered by more than 2km of sediment and there is no sign of it on the surface, Glikson said.

The impact could only be detected by drilling 2km down into the Earth’s crust – as part of geothermal research – to find traces of rocks turned to glass by the enormous heat. One clue that something big happened was what Glikson called “huge deep domes” deep in the crust – signals of the planet rebounding from the impact.

Surrounding rocks are between 300million and 600 million years old, but Glikson said the impact may have occurred much earlier. At that time the Australian continent was part of Earth’s massive single southern continent called Gondwana.

The impact may have caused a global annihilation of living creatures and could have played a significant role in Earth’s evolution, Glikson said.

Glikson and others believe the impact was felt across the world, changing life’s course and spewing a blanket of ash into the atmosphere that blanketed out the sun. “It’s likely to be part of a particular cluster that was linked with a mass extinction at that time,” he said.