Hiawatha crater has been very well preserved although the glacial ice was incredibly effective at erosion. Its condition has fueled talk that the meteorite may have struck as recently as 13,000 years ago.
However, the crater, which is one of the largest in the world, has been definitively dated – and is much older. In fact, they crashed into Earth a few million years after the dinosaurs became extinct, about 58 million years ago.
“Locating the crater was particularly difficult for cracking, so it is very satisfactory that two laboratories in Denmark and Sweden, using different dating methods, came to the same conclusion. As such, I am convinced we have identified the actual crater and its age, which is much older than many people previously thought, said Michael Storey, head of geology at the Natural History Museum in Denmark, in a press release.
When the asteroid hit the North Pole, the North Pole was covered in rainforests with temperatures of around 68°F (20°C). Storey, who was the author of a new paper on the crater published in Science Advances, said the local population would have included crocodiles, turtles and primitive hippopotamus-like animals.
The Hiawatha impact crater can swallow Washington, DC and is about 90% larger than about 200 previously known impact craters on Earth.
It is not yet known whether the meteorite that struck Greenland disrupted the global climate in the same way that the 200-kilometre-wide asteroid that caused the formation of the Chicxulub crater in Mexico – which wiped out the dinosaurs – about 8 million years ago. But the Greenland meteorite It would destroy plant and animal life in the vicinity.
So far, researchers have collected sand and rocks from rivers flowing from the glacier. These samples had been heated up by the impact of the meteorite. They were dated using techniques that detect the natural decay of natural long-lived radioactive isotopes found in the rock.
Crystals of the mineral zircon found in the rock have been dated using uranium and lead dating. Uranium isotopes begin to decay when zircon crystallizes, turning into lead isotopes at a steady and predictable rate. The technique indicated a date about 58 million years ago.
The sand grains were heated with a laser, and the researchers measured the release of argon gas caused by the decay of a rare but naturally occurring radioactive isotope of potassium, known as K-40.
“The half-life of K-40 is exceptionally long (1,250 million years) which makes it ideal for dating deep geological events such as the age of the asteroid Hiawatha,” Storey said.
The technology suggested a time frame similar to a meteor strike.
Co-author Nikolaj Krog-Larsen, the professor at the University of Copenhagen’s GLOBE Institute who first discovered the crater, said.
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