Copenhagen (dpa) – researchers have a 31 km wide battlefield below Greenland Ice protection discovered. With an area larger than Paris, he is one of the 25 largest known craters on earth, reports the team in the magazine Science Advances.
Never before has such a crater been discovered during one of the continental ice sheets of the earth.
At one point, a kilometer-wide iron meteorite must have taken place, according to researcher Kurt Kjær of GeoGenetics Center at the Natural History Museum at Copenhagen University. It was previously impossible to make a date of being under a kilometer ice crater. He was exceptionally well-preserved, from the geological point of view, he could be quite young.
It may even be 12,000 years ago, towards the end of the last glacial period, according to Kjær. The timing of the effect was necessary to understand how impact on life on earth affected. Large meteorite impact can have a lasting effect on the climate.
The border of the crater under the Hiawatha glacier in northern Greenland was not discovered until 2015. In the very edge of the ice, there was a huge circular depression. But the researchers were initially not sure whether it really is the footsteps 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 assumption.
"The new radar system in the AWI research aircraft was exactly what kind of instrument we needed for the measurements," says Olaf Eisen, glaciologist at the Alfred Wegener Institute. The structure would be recognized precisely. «A clear circular boundary, a central height above both the broken and undisturbed layers of ice and basal garbage. Everything that characterizes a meteorite impact. »
During the summer of 2016 and 2017, the research group returned to the site to collect sediment samples and map the tectonic structures in the mountain at the foot of the glacier. "A part of quartz sand washed out of the crater had only deformation characteristics that point to a violent impact," explained Nicolaj Larsen from Aarhus University. This is crucial evidence that the depression under the glacier is a meteorite crater.
The impact of an asteroid in North America about 66 million years ago probably contributed to the eradication of dinosaurs. The diameter is about 180 kilometers. According to a scenario presented at the beginning of the year in the journal "Current Biology", the detonation swept all trees within a radius of about 1500 kilometers. Others disappeared during forest fires all over the world. The emission of sulfur-containing vapors probably led to acid rain, large amounts of soot prevented photosynthesis of plants for years and cooled the world.
Link to the study