Earth’s Oldest Impact Crater Found in Australia, Could Have Warmed the Planet 2.2 Billion Years Ago
TL;DR
Scientists have identified Yarrabubba crater in Western Australia as the Earth’s oldest known impact site, dating back 2.2 billion years. This discovery pushes the known impact record back by over 200 million years and links to a period when Earth was emerging from a glacial phase. Researchers believe the impact may have released enough water vapor to influence the planet’s climate and melt ice sheets. The crater, located in one of Earth’s oldest crustal regions, provides critical insights into ancient meteorite impacts and their effects on Earth’s atmosphere and life.
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A 70-kilometer-wide crater in Western Australia has been confirmed as the Earth’s oldest known impact site. The Yarrabubba crater is approximately 2.2 billion years old, with an error margin of 5 million years, according to research published in Nature Communications.
Due to tectonic movements and erosion, much of the evidence for craters older than 2 billion years has been erased, leaving scientists with limited information on how ancient meteorite impacts may have influenced Earth’s atmosphere and life. While ancient impact materials dating back over 2.4 billion years have been found in parts of Western Australia and South Africa, no associated craters had been identified.
Yarrabubba, situated in one of the planet’s oldest crustal regions known as the Yilgarn craton, extends the known impact record by more than 200 million years. The previous oldest crater was Vredefort crater in South Africa.
Previous estimates placed Yarrabubba’s age between 2.6 billion and 1.2 billion years, based on earlier studies of surrounding rocks. In this new study, scientists accurately determined the crater’s age by dating microscopic structures in rocks that formed during the impact.
Determining the age of Earth’s oldest crater wasn’t the only noteworthy discovery, says study coauthor Timmons Erickson, a geologist at NASA’s Astromaterials Research & Exploration Science Division in Houston. The crater’s age coincides with the end of an ancient glacial period. A computer model suggests that an impact the size of Yarrabubba’s could have released up to 200 trillion kilograms of water vapor into the atmosphere, which the researchers suggest might have warmed the planet and melted the ice sheets.
Yarrabubba crater sits on one of the most ancient pieces of Earth’s crust, called Yilgarn craton in Western Australia. Stars indicate locations where rock samples were taken; the dotted line marks a magnetic signature that researchers used to identify the deeply buried center of the crater.
