The impact craters provide evidence of the biggest and most powerful asteroid impact discovered on Earth, and appear to have been caused by a huge asteroid which broke in two before hitting what is modern day Australia, writes Ian O’Neill for Discovery.
Massive ancient asteroid left “bruises” in Earth’s crust
These days the impact craters are buried 19 miles underneath the surface of central Australia, in rock that is between 300 and 600 million years old. Although geological processes mean that the craters are long gone, the effects of their impact would have been devastating for life on Earth. The impact zone measures around 250 miles wide, and their impact would have been apocalyptic.
“The two asteroids must each have been over 10 kilometers (6.2 miles) across — it would have been curtains for many life species on the planet at the time,” said Andrew Glikson from the Australian National University’s School of Archaeology and Anthropology.
Perhaps the most famous crater, up until this point, was the Chicxulub crater under Mexico’s Yucatan peninsula. The 10-kilometer wide asteroid which hit Earth here is famous for causing the extinction of the dinosaurs, and left an impact crater some 110 miles across. By comparison, the Warburton Basin impact zone is more than twice the size, and was caused by two 10-kilometer wide asteroids.
Mysteries still need to be solved
Scientists discovered the huge crater during a geothermal research project. Teams dug out rock from underneath South Australia and the Northern Territory, and were surprised to find that it had been turned to glass, which is a tell-tale sign of a high-energy impact. The team did not realize the extent of the impact until they carried out further tests.
Magnetic modeling of the Earth’s crust showed bulges in the rock, which they say are ancient bruises from the impact, but some mysteries still need to be solved. For example the Chicxulub impact blasted huge quantities of debris into the air, leaving the Earth covered in sediment which can be detected to this day.
So far there scientists have not discovered a similar layer of sediment related to the impact in Australia, but researchers believe that it may have occurred even longer ago. Another mystery is the lack of a mass extinction event around this time.
Scientists are now searching for further evidence of the doomsday impact, which they believe undoubtedly occurred.