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A large impact crater beneath Hiawatha Glacier in northwest Greenland

Kjær, Kurt H., Larsen, Nicolaj K., Binder, Tobias, Bjørk, Anders A., Eisen, Olaf, Fahnestock, Mark A., Funder, Svend, Garde, Adam A., Haack, Henning, Helm, Veit, Houmark-Nielsen, Michael, Kjeldsen, Kristian K., Khan, Shfaqat A., Machguth, Horst, McDonald, Iain, Morlighem, Mathieu, Mouginot, Jérémie, Paden, John D., Waight, Tod E., Weikusat, Christian, Willerslev, Eske and MacGregor, Joseph A. 2018. A large impact crater beneath Hiawatha Glacier in northwest Greenland. Science Advances 4 (11) , eaar8173. 10.1126/sciadv.aar8173

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Abstract

We report the discovery of a large impact crater beneath Hiawatha Glacier in northwest Greenland. From airborne radar surveys, we identify a 31-kilometer-wide, circular bedrock depression beneath up to a kilometer of ice. This depression has an elevated rim that cross-cuts tributary subglacial channels and a subdued central uplift that appears to be actively eroding. From ground investigations of the deglaciated foreland, we identify overprinted structures within Precambrian bedrock along the ice margin that strike tangent to the subglacial rim. Glaciofluvial sediment from the largest river draining the crater contains shocked quartz and other impact-related grains. Geochemical analysis of this sediment indicates that the impactor was a fractionated iron asteroid, which must have been more than a kilometer wide to produce the identified crater. Radiostratigraphy of the ice in the crater shows that the Holocene ice is continuous and conformable, but all deeper and older ice appears to be debris rich or heavily disturbed. The age of this impact crater is presently unknown, but from our geological and geophysical evidence, we conclude that it is unlikely to predate the Pleistocene inception of the Greenland Ice Sheet.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Additional Information: This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license
Publisher: American Association for the Advancement of Science
ISSN: 2375-2548
Date of First Compliant Deposit: 15 November 2018
Date of Acceptance: 9 October 2018
Last Modified: 03 Apr 2020 13:45
URI: http://orca.cf.ac.uk/id/eprint/116814

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