© Google Earth
has been
presented in the journal
Nature Communications.
Dated at 2.229 billion years, 200 million years older than the next known asteroid strike at Vredefort Dome in South Africa, the impact coincides with the end of a deep freeze known as early
Snowball Earth and could have contributed to the ice thawing.
After this time period there are no rock records of large glacial deposits for 400 million years, says lead author Timmons Erickson from NASA Johnson Space Centre, Houston, US.
"Because of this, we were interested in seeing the role that an impact crater could have had during a time of global glaciations and whether an impact could release enough water vapour, a strong greenhouse gas, to significantly warm the planet."
Calculating the impact of the meteorite on an icy continent, they found that it could have sent half a trillion tonnes of water vapour into the atmosphere, thereby contributing to the global ice melt.
This highlights why the timing of "extraterrestrial bombardment" is important, as the authors write, so its effects on the Earth's environment can be understood.
To date, the historical impact record is fragmented, making it hard to understand how meteorites affect the planet - apart from the
Chicxulub asteroid that triggered the last mass extinction and could explain the ocean's acidification.
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