Hiawatha Crater is very well preserved, despite the fact that glacial ice is incredibly effective against erosion. His condition sparked rumors that the meteorite could have struck 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, it hit the Earth a few million years after the extinction of the dinosaurs, around 58 million years ago.
“Dating the craters was hard to crack, so it was very satisfying that two labs in Denmark and Sweden, using different dating methods, came to the same conclusion. The age, which is much older than many don’t thought so,” Michael Storey, head of geology at the Natural History Museum of Denmark, in a press release.
During the asteroid impact, the North Pole was covered in tropical forests with temperatures approaching 20 degrees Celsius. Storey, author of a new paper on the crater published in Science Advances, said the local population would have included crocodiles, turtles and primitive hippo-like animals.
The Hiawatha impact crater can swallow Washington, DC and is larger than about 90% of the approximately 200 previously known impact craters on Earth.
It remains to be seen whether the meteorite that hit Greenland altered the world’s climate in the same way as the 200-kilometer-wide asteroid that created Mexico’s Chicxulub crater, which wiped out the dinosaurs, did it. about 8 million years ago. But the Greenland meteorite It would have destroyed plant and animal life in the surrounding area.
To determine the history of the glacier, the researchers collected sand and rocks from the rivers flowing from the glacier. These samples may have been heated by the meteor impact. They were dated using techniques that detect the natural decay of long-lived natural radioactive isotopes found in rocks.
The mineral zircon crystals found in the 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. The technique indicated a date around 58 million years ago.
The sand grains were heated with a laser and the researchers measured the release of argon gas, which results from the breakdown of a rare but naturally occurring radioactive isotope of potassium known as K-40.
“K-40’s half-life is exceptionally long (1.25 billion years), making it ideal for dating deep geological events such as the life of the asteroid Hiawatha,” Storey said.
The technique suggested a time frame similar to the meteor impact.
“It’s great to know how old he is now. We have been working hard to find a way to date the crater since we discovered it seven years ago,” said co-author Nikolaj Krog-Larsen, professor at the GLOBE Institute at the University of Copenhagen, who was the first to discover the crater.
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