A large impact crater beneath the ice in northwest Greenland

J. A. MacGregor; K. H. Kjaer; N. K. Larsen; T. Binder; A. A. Bjork; O. Eisen; M. A. Fahnestock; S. Funder; A. A. Garde; H. Haack; V. Helm; M. Houmark-Nielsen; K. K. Kjeldsen; S. A. Khan; H. Machguth; Iain McDonald; Mathieu Morlighem; J. Mouginot; J. D. Paden; T. E. Waight; C. Weikusat; E. Willerslev

A large impact crater beneath the ice in northwest Greenland

J. A. MacGregor, K. H. Kjaer, N. K. Larsen, T. Binder, A. A. Bjork, O. Eisen, M. A. Fahnestock, S. Funder, A. A. Garde, H. Haack, V. Helm, M. Houmark-Nielsen, K. K. Kjeldsen, S. A. Khan, H. Machguth, Iain McDonald, Mathieu Morlighem, J. Mouginot, J. D. Paden, T. E. WaightC. Weikusat, E. Willerslev

Geology

Abstract

A rarely considered element of Arctic system change in the Pleistocene is the possibility and consequences of any large high-latitude impact. We report the discovery of a large impact crater hidden 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.

Original language	English
Journal	American Geophysical Union, Fall Meeting 2018
Volume	41
Publication status	E-pub ahead of print - 2019

Keywords

9315 Arctic region
GEOGRAPHIC LOCATIONDE: 1621 Cryospheric change
GLOBAL CHANGEDE: 1630 Impacts of global change
GLOBAL CHANGEDE: 1637 Regional climate change
GLOBAL CHANGE

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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http://adsabs.harvard.edu/abs/2018AGUFMPP41B..01M

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MacGregor, J. A., Kjaer, K. H., Larsen, N. K., Binder, T., Bjork, A. A., Eisen, O., Fahnestock, M. A., Funder, S., Garde, A. A., Haack, H., Helm, V., Houmark-Nielsen, M., Kjeldsen, K. K., Khan, S. A., Machguth, H., McDonald, I., Morlighem, M., Mouginot, J., Paden, J. D., ... Willerslev, E. (2019). A large impact crater beneath the ice in northwest Greenland. American Geophysical Union, Fall Meeting 2018, 41. Advance online publication. http://adsabs.harvard.edu/abs/2018AGUFMPP41B..01M

MacGregor, JA, Kjaer, KH, Larsen, NK, Binder, T, Bjork, AA, Eisen, O, Fahnestock, MA, Funder, S, Garde, AA, Haack, H, Helm, V, Houmark-Nielsen, M, Kjeldsen, KK, Khan, SA, Machguth, H, McDonald, I, Morlighem, M, Mouginot, J, Paden, JD, Waight, TE, Weikusat, C & Willerslev, E 2019, 'A large impact crater beneath the ice in northwest Greenland', American Geophysical Union, Fall Meeting 2018, vol. 41. <http://adsabs.harvard.edu/abs/2018AGUFMPP41B..01M>

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title = "A large impact crater beneath the ice in northwest Greenland",

abstract = "A rarely considered element of Arctic system change in the Pleistocene is the possibility and consequences of any large high-latitude impact. We report the discovery of a large impact crater hidden 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.",

keywords = "9315 Arctic region, GEOGRAPHIC LOCATIONDE: 1621 Cryospheric change, GLOBAL CHANGEDE: 1630 Impacts of global change, GLOBAL CHANGEDE: 1637 Regional climate change, GLOBAL CHANGE",

author = "MacGregor, {J. A.} and Kjaer, {K. H.} and Larsen, {N. K.} and T. Binder and Bjork, {A. A.} and O. Eisen and Fahnestock, {M. A.} and S. Funder and Garde, {A. A.} and H. Haack and V. Helm and M. Houmark-Nielsen and Kjeldsen, {K. K.} and Khan, {S. A.} and H. Machguth and Iain McDonald and Mathieu Morlighem and J. Mouginot and Paden, {J. D.} and Waight, {T. E.} and C. Weikusat and E. Willerslev",

year = "2019",

language = "English",

volume = "41",

journal = "American Geophysical Union, Fall Meeting 2018",

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TY - JOUR

T1 - A large impact crater beneath the ice in northwest Greenland

AU - MacGregor, J. A.

AU - Kjaer, K. H.

AU - Larsen, N. K.

AU - Binder, T.

AU - Bjork, A. A.

AU - Eisen, O.

AU - Fahnestock, M. A.

AU - Funder, S.

AU - Garde, A. A.

AU - Haack, H.

AU - Helm, V.

AU - Houmark-Nielsen, M.

AU - Kjeldsen, K. K.

AU - Khan, S. A.

AU - Machguth, H.

AU - McDonald, Iain

AU - Morlighem, Mathieu

AU - Mouginot, J.

AU - Paden, J. D.

AU - Waight, T. E.

AU - Weikusat, C.

AU - Willerslev, E.

PY - 2019

Y1 - 2019

N2 - A rarely considered element of Arctic system change in the Pleistocene is the possibility and consequences of any large high-latitude impact. We report the discovery of a large impact crater hidden 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 - A rarely considered element of Arctic system change in the Pleistocene is the possibility and consequences of any large high-latitude impact. We report the discovery of a large impact crater hidden 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.

KW - 9315 Arctic region

KW - GEOGRAPHIC LOCATIONDE: 1621 Cryospheric change

KW - GLOBAL CHANGEDE: 1630 Impacts of global change

KW - GLOBAL CHANGEDE: 1637 Regional climate change

KW - GLOBAL CHANGE

M3 - Journal article

VL - 41

JO - American Geophysical Union, Fall Meeting 2018

JF - American Geophysical Union, Fall Meeting 2018

ER -

A large impact crater beneath the ice in northwest Greenland

Abstract

Keywords

UN SDGs

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