Scientists have determined that the Earth’s oldest asteroid crater – named the Yarrabubba crater – happened 2.229 billion years ago. The crater, which is located between Sandstone and Meekatharra in Western Australia’s outback, measures 43 miles wide.
A team of experts from Curtin University in Perth were able to determine the exact age of the crater by using isotopic analysis of the minerals found at the impact zone. They studied zircon and monazite minerals that were found at the bottom of the Yarrabubba crater and were “shock recrystallized” because of the impact. Their study was published in Nature Communications and can be read in full here.
It was always agreed upon that the Yarrabubba crater was one of the oldest on Earth but scientists weren’t able to determine its exact age until recently. In fact, it’s so old that it happened 200 million years before the next oldest impact zone that’s located in South Africa and called the Vredefort crater.
What’s even more interesting is that this impact may have helped lift our planet out of an ancient ice age called “Snowball Earth”. Curtin University Professor Chris Kirkland explained, “Now we know the Yarrabubba crater was made right at the end of what’s commonly referred to as the early Snowball Earth – a time when the atmosphere and oceans were evolving and becoming more oxygenated and when rocks deposited on many continents recorded glacial conditions.” “This twist of fate suggests that the large meteorite impact may have influenced global climate,” added Associate Professor Nicholas Timms.
Half a trillion tons of water vapour would have been sent into Earth’s atmosphere with such a large asteroid hitting a continent covered in ice, therefore, possibly causing changes to our climate. “This finding raises the question whether this impact may have tipped the scales enough to end glacial conditions,” said Timms.
Their study is very important in properly dating ancient craters, some of which may even be older than Yarrabubba. “Yarrabubba is about half the age of the Earth and it raises the question of whether all older impact craters have been eroded or if they are still out there waiting to be discovered,” stated Dr. Aaron Cavosie from Curtin University. As a matter of fact, materials that came from an ancient impact crater have been found in Africa and Australia and they date back to over 2 billion years old, however, the craters in which they came from are still unidentified.