Hiawatha Crater has been very well preserved although glacial ice is very effective in erosion. Its conditions have sparked talk that the meteorite may have hit as recently as 13,000 years ago.
However, the crater, which is one of the largest in the world, is age-determined – and much older. In fact, they hit Earth several million years after the dinosaurs went extinct, about 58 million years ago.
“Finding the crater is very difficult to crack, so it is very satisfying that two laboratories in Denmark and Sweden, using different dating methods, have come to the same conclusion. Because of that, I believe we have identified the actual crater,” said Michael Storey, head of geology at the Museum of History.Normal in Denmark, in a press release: “Age, which is much older than many previously thought.”
When the asteroid hit the North Pole, it was covered in rainforest with temperatures around 68°F (20°C). Storey, who is the author of a new paper on craters published in Science Advances, said the local population included crocodiles, turtles and primitive hippos-like animals.
The Hiawatha collision crater can engulf Washington, DC and is about 90% larger than about 200 previously known collision craters on Earth.
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It is not yet known whether the meteorite that hit Greenland disturbed global climate in the same way as the 200-kilometer-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 will destroy the plant and animal life in the vicinity.
So far, researchers have collected sand and rock from rivers flowing from the glacier. This sample has been heated by a meteorite impact. They were dated using a technique that detects the natural decay of naturally occurring, long-lived radioactive isotopes found in rock.
Crystals of the mineral zircon found in rock have been dated using uranium and lead dating. Uranium isotopes begin to decay as zircon crystallizes, turning into lead isotopes at a steady and predictable rate. This technique shows the date to 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.
“K-40’s very long half-life (1,250 million years) makes it ideal for dating deep geological events such as the age of the asteroid Hiawatha,” Storey said.
This technology suggests a time frame similar to that of a meteor strike.
Co-author Nikolaj Krog-Larsen, professor at the University of Copenhagen’s GLOBE Institute who first discovered the crater, said.
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