Copenhagen (dpa) – researchers have a crater impacted by 31 km Greenland An ice cap discovered. With an area larger than Paris, it is one of the 25 largest known craters on earth, according to a team in Science Advances.
Never before has such a crater been detected under one of the continental ice sheets of the earth.
According to one study, Kurt Kjær of the GeoGenetics Center at the Natural History University at the University of Copenhagen, at one point, the meteorite of the meteorological cell had to guess the place. Early it is not possible to give the crater under a kilometer of ice crater. It was exceptionally preserved, from a geological point of view, could be quite young.
It may have been 12,000 years, towards the end of the last ice age, according to Kjær. The impact time was essential to understanding the impact on life on Earth. The great impacts of the meteorite can permanently affect the climate.
Abbreviations of the Crater under the Hiavath Glacier in northern Greenland were first discovered in 2015. At the very edge of the ice sheet there was a huge circular depression. But at first, scientists were not sure whether it was a real imprint of influence. Only when the team of the Alfred Vegener Institute (AVI) in Bremerhaven mapped the area from an aircraft with powerful icebreakers confirmed the assumption.
"The new radar system of the research aircraft AVI was exactly the type of instrument we needed to measure," said Olaf Eisen, glaciologist at the Alfred Vegener Institute. The structure was to be recognized exactly. «Clear circular boundary, central altitude, above it and disturbed and unhindered layers of ice and basal remains. All that characterizes the impact of the meteorite. »
During the years 2016 and 2017, the research team returned to the site for collecting sediment samples and mapping tectonic structures in the wall at the foot of the glacier. "Part of quartz sand washed out of the crater had only those characteristics of deformation that indicate violence," explained Nikolai Larsen of the University of Aarhus. This is the ultimate proof that depression under the glacier is a crater of a meteorite.
The impact of asteroids in North America some 66 million years ago probably contributed significantly to the extinction of dinosaurs. Its diameter is about 180 kilometers. According to the scenario presented at the beginning of the year in the journal "Current Biology", the detonation ran across all the trees within a circle of about 1500 kilometers. Others disappeared during forest fires around the world. The emission of sulfur vapor has probably led to acid rain, large quantities of soot have obstructed the photosynthesis of plants for years, and cooled the world.
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