A large impact crater beneath Hiawatha Glacier in northwest Greenland

Kurt H. Kjær; Nicolaj K. Larsen; Tobias Binder; Anders Anker Bjørk; Olaf Eisen; Mark Fahnestock; Svend Visby Funder; Adam A. Garde; Henning Haack; Veit Helm; Michael Houmark-Nielsen; Kristian Kjellerup Kjeldsen; Shfaqat Khan; Horst Machguth; Iain McDonald; Mathieu Morlighem; Jéremie Mouginot; John D. Paden; Tod Earle Waight; Christian Weikusat; Eske Willerslev; Joseph MacGregor

doi:10.1126/sciadv.aar8173

A large impact crater beneath Hiawatha Glacier in northwest Greenland

Kurt H. Kjær, Nicolaj K. Larsen, Tobias Binder, Anders Anker Bjørk, Olaf Eisen, Mark Fahnestock, Svend Visby Funder, Adam A. Garde, Henning Haack, Veit Helm, Michael Houmark-Nielsen, Kristian Kjellerup Kjeldsen, Shfaqat Khan, Horst Machguth, Iain McDonald, Mathieu Morlighem, Jéremie Mouginot, John D. Paden, Tod Earle Waight, Christian WeikusatEske Willerslev, Joseph MacGregor

Geologi

33 Citationer (Scopus)

89 Downloads (Pure)

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.

Originalsprog	Engelsk
Artikelnummer	eaar8173
Tidsskrift	Science Advances
Vol/bind	4
Udgave nummer	11
Antal sider	12
ISSN	2375-2548
DOI	https://doi.org/10.1126/sciadv.aar8173
Status	Udgivet - 14 nov. 2018

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10.1126/sciadv.aar8173Licens: CC BY

A large impact crater beneath Hiawatha Glacier in northwest GreenlandForlagets udgivne version, 4 MBLicens: CC BY-NC

Citationsformater

Kjær, K. H., Larsen, N. K., Binder, T., Bjørk, A. A., Eisen, O., Fahnestock, M., Funder, S. V., Garde, A. A., Haack, H., Helm, V., Houmark-Nielsen, M., Kjeldsen, K. K., Khan, S., Machguth, H., McDonald, I., Morlighem, M., Mouginot, J., Paden, J. D., Waight, T. E., ... MacGregor, J. (2018). A large impact crater beneath Hiawatha Glacier in northwest Greenland. Science Advances, 4(11), Artikel eaar8173. https://doi.org/10.1126/sciadv.aar8173

Kjær, KH, Larsen, NK, Binder, T, Bjørk, AA, Eisen, O, Fahnestock, M, Funder, SV, Garde, AA, Haack, H, Helm, V, Houmark-Nielsen, M, Kjeldsen, KK, Khan, S, Machguth, H, McDonald, I, Morlighem, M, Mouginot, J, Paden, JD, Waight, TE, Weikusat, C, Willerslev, E & MacGregor, J 2018, 'A large impact crater beneath Hiawatha Glacier in northwest Greenland', Science Advances, bind 4, nr. 11, eaar8173. https://doi.org/10.1126/sciadv.aar8173

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title = "A large impact crater beneath Hiawatha Glacier in northwest Greenland",

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.",

author = "Kj{\ae}r, {Kurt H.} and Larsen, {Nicolaj K.} and Tobias Binder and Bj{\o}rk, {Anders Anker} and Olaf Eisen and Mark Fahnestock and Funder, {Svend Visby} and Garde, {Adam A.} and Henning Haack and Veit Helm and Michael Houmark-Nielsen and Kjeldsen, {Kristian Kjellerup} and Shfaqat Khan and Horst Machguth and Iain McDonald and Mathieu Morlighem and J{\'e}remie Mouginot and Paden, {John D.} and Waight, {Tod Earle} and Christian Weikusat and Eske Willerslev and Joseph MacGregor",

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T1 - A large impact crater beneath Hiawatha Glacier in northwest Greenland

AU - Kjær, Kurt H.

AU - Larsen, Nicolaj K.

AU - Binder, Tobias

AU - Bjørk, Anders Anker

AU - Eisen, Olaf

AU - Fahnestock, Mark

AU - Funder, Svend Visby

AU - Garde, Adam A.

AU - Haack, Henning

AU - Helm, Veit

AU - Houmark-Nielsen, Michael

AU - Kjeldsen, Kristian Kjellerup

AU - Khan, Shfaqat

AU - Machguth, Horst

AU - McDonald, Iain

AU - Morlighem, Mathieu

AU - Mouginot, Jéremie

AU - Paden, John D.

AU - Waight, Tod Earle

AU - Weikusat, Christian

AU - Willerslev, Eske

AU - MacGregor, Joseph

PY - 2018/11/14

Y1 - 2018/11/14

N2 - 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.

AB - 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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DO - 10.1126/sciadv.aar8173

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