Meteorite Impact 2 Billion Years Ago May Have Ended an Ice Age

Pablo Tucker
January 22, 2020

Lead author Dr Timmons Erickson, from Curtin's School of Earth and Planetary Sciences and NASA's Johnson Space Center, together with a team including Professor Chris Kirkland, Associate Professor Nicholas Timms and Cavosie, all from Curtin's School of Earth and Planetary Sciences, analysed the minerals zircon and monazite that were "shock recrystallized" by the asteroid strike, at the base of the eroded crater to determine the exact age of Yarrabubba.

This is how the team discovered the crater's age.

Yarrabubba crater in Western Australia stretches roughly 40 miles across.

At the time, the landscape may have been ice-covered and the impact would have vaporised a large volume into the atmosphere.

The Yarrabubba impact also coincided with the disappearance of glacial deposits, which are absent in the rock record for 400 million years since the impact.

However, researchers at Curtin University have found that new asteroid impact crater in Australia dates back even further to 2.229 billion years.

Scientists now believe an ancient crater in the Australian outback is the oldest known asteroid impact and might have brought about the end of Snowball Earth, a time hypothesized as when the entire planet was essentially a giant ball of ice. Since water vapour is an important gas, it may have been enough to tip the scales to trigger global warming.

Researchers think meteorite impacts have had dramatic effects on Earth's climate throughout our planet's history.

'Our findings highlight that acquiring precise ages of known impact craters is important - this one sat in plain sight for almost two decade before its significance was realised, ' said Dr Aaron Cavosie at Curtin University.

The impact crater is about half the age of Earth itself, making it the oldest known impact structure on the planet.

The findings were published in the journal Nature Communications on Tuesday.

In order to reveal the precise date when the asteroid responsible for the crater hit Earth, Australian geologists analyzed minerals extracted from deep cores around the crater site.

If the ice had covered the entire planet, life may have died out. This vast quantity of greenhouse gas might have considerably warmed the planet, potentially causing a climate shift that relieved some regions out of an icy embrace, spelling the end for this frozen era. It was a dramatic event in the planet's evolution placing huge pressures on surviving (still microscopic) creatures and nearly destroying life on Earth altogether. "But placing that right with the context of Earth's other events makes it become really very interesting".

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