The impact zone of a meteorite that may have hit the Earth in the Australian outback around 300 million years ago is double the size originally thought, making it the largest ever discovered. The crater caused by the collision has vanished with time but signs of a possible double impact exist below the surface and were discovered during drilling for another research project. The research team say it is the largest impact zone discovered in the world, with the scars reaching more than 190km long and 30km deep.
“The two asteroids must each have been over 10 kilometres across – it would have been curtains for many life species on the planet at the time,” Glikson said in an article for ANU in March. “Large impacts like these may have had a far more significant role in the Earth’s evolution than previously thought.”
The new research regarding the impact at the Warburton Basin site in central Australia has been published in journal Tectonophysics on Mar. 7.
The original discovery of the Warburton Basin site in 2013 was widely reported, but the size of the site was at the time believed to be only 200km and the existence of a secondary scar had not been confirmed. Glickson said at the time, the meteorite would have had “a global impact, not just regional.”
It is generally believed by geophysicists that a meteorite that hit the Yucatan peninsula in Mexico 65 million years ago caused the mass extinction of the dinosaurs. The size of the crater is much smaller than the new discovery at just 180 kilometers, yet the meteor that hit is believed to be of similar size at 10km wide.
In the most recent paper, scientists say a layer of sediment that forms from the dust after a meteorite hits — as is the case in the Yucatan example — is not present in the rocks that are 300 million years old. This lack of evidence has left scientists confused to the extent of the effect the collision had on the Earth.
“It’s a mystery – we can’t find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300 million years,” Glikson said. Read more…