'Earth's oldest crater from space rock impact revealed'

The 70-kilometre wide Yarrabubba crater in Western Australia is the Earth's oldest preserved impact structure by over 200 million years, according to a study which revealed that a meteorite hit the site more than 2.2 billion years ago.

The study, published in the journal Nature Communications, found that a meteorite hit the site 2.229 billion years ago by assessing the age of shocked minerals within the crater which revealed signs of impact related deformation and heating.

According to the researchers, including Timmons Erickson from NASA Johnson Space Center in the US, the Yarrabubba impact structure is regarded as one of Earth's oldest craters, but lacked a precise age until now.

Erickson and his colleagues assessed special minerals within the crater like monzogranite, zircon, and monazite grains, which they said preserved a range of impact-related microstructures.

Based on the analysis, the researchers said the precise age of the impact event could be 2.229 billion years with a margin of error of five million years.

"This result establishes Yarrabubba as the oldest recognised meteorite impact structure on Earth, extending the terrestrial cratering record back by more than 200 million years," the researchers wrote in the study.

They added that this new date for Yarrabubba coincides with a period of glaciation in the same region.

Based on impact simulations, the scientists said if the Yarrabubba-forming meteorite collided into a continental ice sheet -- like modern day Antarctica -- it may have released between 87 trillion and 5,000 trillion kilograms of water vapour into the atmosphere instantaneously.

According to the scientists this may have potentially played a role in modifying the Earth's climate during this period.