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31-km wide meteorite crater under Greenland’s ice-shield investigated

Rendering of Greenland’s northwestern coastline with the impact crater. Source: Natural History Museum of Denmark

An international team of scientists used a new remote radar system and debris analysis to verify the deep deformation in the bedrock

An international research team has investigated a large meteorite impact crater buried under the ice-sheet in northern Greenland. It measures more than 31 km in diameter, corresponding to an area bigger than Paris, and placing it among the 25 largest impact craters on Earth.

„The crater is exceptionally well-preserved, and that is surprising because glacier ice is an efficient erosive agent that would have quickly removed traces of the impact. But that means the crater must be rather young from a geological perspective. Its condition strongly suggests that it formed after ice began to cover Greenland, so younger than 3 million years old and possibly as recently as 12,000 years ago – toward the end of the last ice age” says Professor Kurt H. Kjær from the Center for GeoGenetics at the Natural History Museum of Denmark.

The deformation had first been discovered in July 2015. Now, the scientists could verify that the deformation really is a crater by radar measurements from a research aircraft.

Size comparison.The bedrock topography under the Hiawatha glacier.

„The radar system that colleagues from the University of Kansas developed custom-made for our purposes exceeded all expectations and imaged the depression in stunning detail. A distinctly circular rim, central uplift, disturbed and undisturbed ice layering, and basal debris. It’s all there,” adds Prof. Olaf Eisen, glaciologist at the German Alfred Wegener Institute (AWI).

The research team also investigated samples of sediments washed out from the depression through a meltwater channel. „Some of the quartz had planar deformation features indicative of a violent impact, and this is also a conclusive evidence,“ says Professor Nicolaj K. Larsen from Aarhus University.

Earlier studies have shown that large impacts can profoundly affect Earth’s climate, with major consequences for life on the planet at the time. „The next step in the investigation will be to confidently date the impact. This will be a challenge because it will probably require recovering material from the bottom of the structure,” concludes Professor Kjær.

„A large impact crater beneath Hiawatha Glacier in northwest Greenland“, Kurt H. Kjær, Nicolaj K. Larsen, Tobias Binder, Anders A. Bjørk, Olaf Eisen, Mark A. Fahnestock, Svend Funder, Adam A. Garde, Henning Haack, Veit Helm, Michael Houmark-Nielsen, Kristian K. Kjeldsen, Shfaqat A. Khan, Horst Machguth, Iain McDonald, Mathieu Morlighem, Jérémie Mouginot, John D. Paden, Tod E. Waight, Christian Weikusat, Eske Willerslev, Joseph A. MacGregor, published in Science Advances

Source: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI)

Video

Radar measurements from a research aircraft.

(02.12.2018, USA: 12.02.2018)