Thursday , July 29 2021

Greenland was hit by a large meteorite



Under the Greenland ice sheet is a crater with a large impact, which probably originated only around 12,000 years ago. He was found and examined by a research team with participation from the University of Freiburg.

Researcher Kurt Kjær collected sand at the Hiawatha Glacier in Greenland. From the sand, scientists expect information about the impact of meteorite craters under the glacier. (Photo: Svend Funder)

Researcher Kurt Kjær collected sand at the Hiawatha Glacier in Greenland. From the sand, scientists expect information about the impact of meteorite craters under the glacier. (Photo: Svend Funder)

(AP) Inside the crater, the whole city of Paris will find a place, said Horst Machguth of the University of Freiburg, according to a notice from the campus on Wednesday. "The crater was formed when an iron meteorite more than one kilometer in diameter hit northern Greenland." Since then he has been hidden under almost a kilometer of ice.

The 31 kilometer impact crater is one of the 25 largest in the world, according to an international team led by Kurt Kjær of the Center for Geogenetics at the Museum of Natural History at the University of Copenhagen in the journal Science Advances. Never before had a crater like that been found under one of the continental ice sheets of the earth.

The right young crater

"The crater is very well preserved," Machguth said. This is surprising, because glacier ice can erode the soil heavily and thus eliminate its impact footprint relatively soon. "This shows, in our opinion, that the crater can be very young from a geological point of view."

Radar measurements above the Hiawatha glacier have revealed not only the thickness of the ice, but also the topography of the underlying meteorite crater. (Photo: Danish Natural History Museum, Cryospheric Science Lab, NASA Goddard Space Flight Center, Greenbelt (MD), USA)

Radar measurements above the Hiawatha glacier have revealed not only the thickness of the ice, but also the topography of the underlying meteorite crater. (Photo: Danish Natural History Museum, Cryospheric Science Lab, NASA Goddard Space Flight Center, Greenbelt (MD), USA)

It might even have been made only 12,000 years ago towards the end of the last glacial period, said Kjær. Dating from the previous crater is not possible, but should be the focus of further investigation. Time of impact is very important to understand how the impact on life on Earth has affected Kjaer. The impact of large meteorites can have a lasting effect on the climate.

The outline of the crater under the Hiawatha glacier in northern Greenland was first discovered in 2015. At the extreme edge of the ice there is a very large circular depression. But scientists were initially not sure whether it was really a trace of an impact. Only when a team from the Alfred Wegener Institute (AWI) in Bremerhaven mapped the area of ​​a plane with ice radar that strongly confirmed this assumption.

Measurement of radar and quartz sand

"The new radar system from the AWI research aircraft is exactly the type of instrument we need for measurement," said Olaf Eisen, a glaciologist at the Alfred Wegener Institute. The structure must be recognized correctly. «Clearly circular borders, middle altitude, above which the ice and basal debris are disturbed and undisturbed. Everything that characterizes the impact of meteorites. »

The crater found is 31 kilometers in diameter. According to calculations, the meteorite that triggered it must be more than one kilometer in size. (Photo: Danish Natural History Museum, Cryospheric Science Lab, NASA Goddard Space Flight Center, Greenbelt (MD), USA)

The crater found is 31 kilometers in diameter. According to calculations, the meteorite that triggered it must be more than one kilometer in size. (Photo: Danish Natural History Museum, Cryospheric Science Lab, NASA Goddard Space Flight Center, Greenbelt (MD), USA)

In the summer of 2016 and 2017, the research team returned to the site to collect sediment samples and map tectonic structures in the rock at the foot of the glacier. "The part of quartz sand that is swept from the crater has a deformation characteristic that leads to the impact of violence," explained Nicolaj Larsen of Aarhus University. This is clear evidence that depression under the glacier is a meteorite crater.

The impact of asteroids in North America about 66 million years ago might have contributed significantly to the extinction of dinosaurs. The diameter of the crater is around 180 kilometers. According to the scenario presented in the journal "Current Biology" at the beginning of the year, detonation swept away all trees in a radius of about 1,500 kilometers. Others are lost in forest fires around the world. Sulfur vapor emissions may cause acid rain, large amounts of soot block the plant photosynthesis and cool the world for years.


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