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Sci Adv. 2018 Nov 14;4(11):eaar8173. doi: 10.1126/sciadv.aar8173. eCollection 2018 Nov.

A large impact crater beneath Hiawatha Glacier in northwest Greenland.

Author information

1
Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Copenhagen, Denmark.
2
Department of Geoscience, Aarhus University, Aarhus, Denmark.
3
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
4
Department of Earth System Science, University of California, Irvine, Irvine, CA, USA.
5
NASA Jet Propulsion Lab, Pasadena, CA, USA.
6
Department of Geosciences, University of Bremen, Bremen, Germany.
7
Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA.
8
Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
9
Maine Mineral and Gem Museum, Bethel, ME, USA.
10
Geobiology and Minerals Section, Natural History Museum, University of Copenhagen, Copenhagen, Denmark.
11
Department of Earth Sciences, University of Ottawa, Ottawa, Ontario, Canada.
12
DTU Space, National Space Institute, Department of Geodesy, Technical University of Denmark, Kongens Lyngby, Denmark.
13
Department of Geosciences, University of Fribourg, Fribourg, Switzerland.
14
Department of Geography, University of Zurich, Zurich, Switzerland.
15
School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff, UK.
16
Université Grenoble Alpes, CNRS, INP, Grenoble, France.
17
Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, KS, USA.
18
Department of Geosciences and Natural Resources Management (Geology Section), University of Copenhagen, Copenhagen, Denmark.
19
Department of Zoology, University of Cambridge, Cambridge, UK.
20
Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, UK.
21
Cryospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD, USA.

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.

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