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 Earth a few million years after the dinosaurs went extinct, about 58 million years ago.
“crater dating was hard to break, so it was very satisfying that two labs in Denmark and Sweden, using different methods of dating, came to the same conclusion. The age, which is much older than many people thought,” Michael Storey, head of geology at Denmark’s Natural History Museum, in a press release.
When the asteroid impacted, the North Pole was covered in rainforests 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 hippopotamus-like animals.
Impact crater Hiawatha may swallow Washington, DC and is larger than about 90% of the 200 or so previously known impact craters on Earth.
It remains to be seen whether the meteorite that struck Greenland altered the global climate in the same way that the 200-kilometre-wide asteroid that created the Mexican Chicxulub Crater, which wiped out the dinosaurs, did about 8 million years ago. But the Greenland meteorite It would have destroyed plant and animal life in the vicinity.
To determine the glacier’s history, researchers collected sand and rocks from rivers flowing from the glacier. These samples could have been heated by the meteor impact. They have been dated using techniques that detect the natural decay of natural long-lived radioactive isotopes found in the rocks.
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, which results from the decomposition of a rare but naturally occurring radioactive isotope of potassium known as K-40.
“The half-life of K-40 is exceptionally long (1.25 billion years), which makes 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 it is now. We’ve 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 University of Copenhagen’s GLOBE Institute, who was the first to discover the crater.
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