Sunday , November 29 2020

Greenland crater under ice shelf reveals asteroid hit: study



When thinking about a massive asteroid that collides with the earth, the eradication of the dinosaurs 65 million years ago is likely to be considered.

The current theory is the Chicxulub crater, 115 miles wide and located on the Yucatán Peninsula in Mexico, was the landing site of a deadly asteroid that crashed into the world tens of millions of years ago and set a chain of events killing the dinosaurs, ScienceDaily noted.

Now, a study published in the journal Scientific Advances describes the discovery of another asteroid crater likely to be affected by the earth's relatively recent history, although this is not as great as the catastrophic crater found in Mexico. And its true effect is still unknown.

This new crater was found under the ice shelves of the Hiawatha glacier in Greenland, says the study. At 19 miles wide, it is larger than Paris or Washington, D.C. – and probably struck sometime in the world's latest history, judging by how well preserved it is, says the study.

"Until now, it has not been possible to date the crater directly, but its state strongly suggests that it formed after the ice started covering Greenland, younger than 3 million years old and possibly as recently as 12,000 years ago – towards the end of the last ice age, says study author Kurt H. Kjær in a press release from Copenhagen University.

The discovery was made thanks to NASA's Operation IceBridge, an initiative to scan "changes in polaris" and make that information public for others to review maps, according to NASA. Researchers at the Copenhagen Center for GeoGenetics at the Danish Museum of Natural History helped investigate data from NASA and discovered the shape of what appeared to be a great crater hidden under the ice in Greenland in July 2015.

The NASA glaciologist Joseph MacGregor worked with the researchers after his first discovery and looked at "radar measurements" of the possible crater that was taken by a research plan from the Alfred Wegener Institute in Germany, explains the press release.

And what did they find?

"A clear circular rim, central uplift, disturbed and undisturbed ice storage, and basalt junk," MacGregor said in the press release.

In other words, the proof that it really is a crater caused by an asteroid collision is "all there," MacGregor said.

Researchers also found a channel where some of the melted water in the glacier was free-flowing – and used it to collect different rocks to look for more evidence of a high-impact.

They found shocked quartz and glass, formed after a major collision, as noted by Gizmodo. National Geographic reported that it was estimated that the asteroid would have been about three quarters of a mile wide with a mass of up to 12 billion tons.

There is also a 20-ton meteorite at the Geological Museum in Copenhagen – not far from the crater – which led researchers to theorize if the two were affiliated, noted the study.

Kjær told National Geographic that even if it is not included in the paper, his results can ultimately help to support the Younger Dryas consequence hypothesis, which says that large animals like mothers died during the Ice Age because of fires caused by great influence.

But there are still long ways to go before that argument can be supported, Dear newspaper warned.

"This can generate a lot of discussion, and we need to find out," he said, according to National Geographic. "We will not know until we have a real date."

Nicolaj K. Larsen, co-author of the study, told Gizmodo that researchers are already trying to figure out how to get a more specific date of impact.

"We are currently trying to come up with ideas about how to mitigate the consequences," she said to the outlet. "An idea is to drill through the ice and get bedrock samples that can be used for numerical dating."


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