Written by Beth Askham Image: Newly discovered impacts suggest an asteroid broke up and hit the Earth over 300 million years ago.
Credit: ©istock.com/SIYAMA9
Deep underground in the centre of Australia is evidence of the biggest asteroid impact in the Earth’s history.
It wasn’t just a single impact, but a twin strike from a meteorite that may have split into two as it plummeted towards Earth.
Researchers unexpectedly found signs of the collisions in the middle of Australia, at the tripoint where South Australia, Queensland and the Northern Territory meet. They were drilling almost two kilometres into the Earth’s surface, investigating the geothermal energy in the area.
The drill core they pulled out contained traces of rocks that had turned to glass, a sign of the extreme temperature and pressure caused by a major impact.
The exact date of the event remains unclear. The surrounding rocks are 300 to 600 million years old.
The researcher who found the craters, Andrew Glikson, says it’s all very much a mystery. “We can’t find an extinction event that matches these collisions. I have a suspicion the impacts could be older than 300 million years,” he says.
“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,” says Andrew.
The two asteroid impact zones total more than 400 kilometres across, in the Warburton Basin in Central Australia. “The two asteroids must each have been over 10 kilometres across,” says Andrew.
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