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A team of Scientists has discovered a 400 km-wide impact zone from a giant meteorite in central Australia – the largest asteroid crater ever found on Earth.
Dr Andrew Glikson from the Australian National University (ANU) and his colleagues found a 400 kilometer-wide impact zone from a huge asteroid that broke in two, just moments before it hit the Earth in central Australia.
The impact happened millions of years ago and it’s crater has long disappeared. Researchers discovered two scars made by the impacts hidden deep in the Earth’s crust.
Glikson said the discovery came by chance. The impact zone was found during drilling as part of geothermal research, in an area near the borders of Queensland, South Australia and the Northern Territory.
“The two meteorites must each have been over 10 kilometers wide, ending the life of species on the planet at the time,” he explained. “Huge impacts like these may have had a far more significant role in the Earth’s evolution than previously thought,” Glikson added.
The exact time of the huge impacts remains unclear. According to the team of geologists, the surrounding rocks are up to 300 million years old, but evidence of this kind left by other asteroid strikes is lacking.
For example, a large asteroid strike which happened 66 million years ago sent up a veil of ash that is found as a layer of sediment in rocks all around the world. The veil is thought to have led to the extinction of a great proportion of the life species on the planet, including many dinosaurs.
However, a similar layer has not been discovered in sediments around 300 million years old, the scientist said.
“It’s a mystery. We can’t find an event that matches these impacts. I suspect the collision could be older than 300 million years,” he said.
The researchers drilled more than two kilometers into the Earth’s crust, discovering traces of rocks that have been turned to glass by the extreme heat caused by a major impact. Magnetic mapping of the deep crust in the area pointed out out bulges hidden deep in the Earth, which are rich in iron and magnesium, comparable to the composition of the Earth mantle.
“There are two huge deep domes in the crust, formed by the Earth’s crust rebounding after the huge impacts, and bringing up rock from the mantle below,” Glikson added.
Image Source: Guardian Liberty Voice
