A large impact crater beneath Hiawatha Glacier in northwest Greenland

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  • Kurt H. Kjær, Københavns Universitet
  • ,
  • Nicolaj K. Larsen
  • Tobias Binder, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
  • ,
  • Anders A. Bjørk, Københavns Universitet, UC Irvine, Jet Propulsion Laboratory/California Institute of Technology
  • ,
  • Olaf Eisen, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Universitat Bremen
  • ,
  • Mark A. Fahnestock, University of Alaska Fairbanks
  • ,
  • Svend Funder, Københavns Universitet
  • ,
  • Adam A. Garde, Geo-logical Survey of Denmark and Greenland
  • ,
  • Henning Haack, Maine Mineral and Gem Museum, Københavns Universitet
  • ,
  • Veit Helm, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
  • ,
  • Michael Houmark-Nielsen, Københavns Universitet
  • ,
  • Kristian K. Kjeldsen, Københavns Universitet, Geo-logical Survey of Denmark and Greenland, University of Ottawa
  • ,
  • Shfaqat A. Khan, Technical University of Denmark
  • ,
  • Horst Machguth, University of Fribourg, Physik-Institut, Universitat Zürich-Irchel
  • ,
  • Iain McDonald, Cardiff University
  • ,
  • Mathieu Morlighem, UC Irvine
  • ,
  • Jérémie Mouginot, UC Irvine, Univ. Grenoble Alpes
  • ,
  • John D. Paden, University of Kansas Lawrence
  • ,
  • Tod E. Waight, Københavns Universitet
  • ,
  • Christian Weikusat, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
  • ,
  • Eske Willerslev, Københavns Universitet, Cambridge University, Wellcome Trust Sanger Institute, Cambridge
  • ,
  • Joseph A. MacGregor, NASA Goddard Space Flight Center

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.

OriginalsprogEngelsk
Artikelnummereaar8173
TidsskriftScience Advances
Vol/bind4
Nummer11
ISSN2375-2548
DOI
StatusUdgivet - 2 nov. 2018

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