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The impact of an asteroid in North America probably contributed significantly to the extinction of dinosaurs. Greenland was once struck by a giant from space, researchers have now discovered.
Kopenhagen (dpa) – researchers found a 31 km crater under the Greenland ice. With an area larger than Paris, it is one of the 25 largest known impact craters on earth, the team said in the journal Science Advances.
Never before has such a crater been found under one of the continental ice sheets of the earth.
At one point, a one-kilometer-long iron meteorite must have hit the spot, according to researchers around Kurt Kjær from the GeoGenetics Center at the Natural History Museum of the University of Copenhagen. A dating down to one kilometer of ice crater was not possible before. It was extremely well preserved, from a geological point of view, it could be quite new.
It may even 12,000 years ago, towards the end of the last ice age, according to Kjær. The timing of the impacts was necessary to understand how the impact on life on Earth had an impact. The major effects of meteorite can have a lasting effect on the climate.
The contours of the crater under the Hiawatha glacier in northern Greenland were first discovered in 2015. At the edge of the ice there was a huge circular depression. But scientists were initially not sure if they really are the traces of an impact. Only when a team of the Alfred Wegener Institute (AWI) in Bremerhaven mapped the area from the aircraft with a powerful ice radar confirmed the case.
"The new radar system of the AWI research aircraft was exactly the kind of instrument we needed for measurements," said Olaf Eisen, a glacier at the Alfred Wegener Institute. The structure had to be exactly identified. "A clearly circular boundary, a central altitude, above which both the disturbed and the undisturbed layers of ice and basic debris. Everything that characterizes a meteorite effect. »
In the summer of 2016 and 2017, the research team returned to the site to collect sediment samples and map the tectonic structures to the rock at the foot of the glacier. "Part of the quartz sand escaped from the crater had only those deformation features that show violent effects," explained Nicholas Larsen of the University of Aarhus. These are absolutely evidence that depression under the glacier is a meteor crater.
The impact of an asteroid in North America about 66 million years ago has probably contributed significantly to the extinction of dinosaurs. Its diameter is about 180 km. According to a scenario presented at the beginning of the year in Current Biology, the explosion swept all the trees in a radius of about 1500 kilometers. Others have disappeared during forest fires worldwide Sulfur vapors have probably led to acid rain, large amounts of soot prevented plant photosynthesis for years and searched the world.
Link to the study