Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland
The 31-km-wide Hiawatha impact crater was recently discovered under the ice sheet in northwest Greenland, but its age remains uncertain. Here we investigate solid organic matter found at the tip of the Hiawatha Glacier to determine its thermal degradation, provenance, and age, and hence a maximum ag...
Published in: | Geology |
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Language: | English |
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2020
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Online Access: | https://curis.ku.dk/portal/da/publications/pleistocene-organic-matter-modified-by-the-hiawatha-impact-northwest-greenland(9a0d5622-09b6-4fa4-b39e-fc2a01635862).html https://doi.org/10.1130/G47432.1 https://curis.ku.dk/ws/files/288731715/Pleistocene_organic_matter_modified_by_the_Hiawatha_impact_northwest_Greenland_publisher_version_.pdf |
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ftcopenhagenunip:oai:pure.atira.dk:publications/9a0d5622-09b6-4fa4-b39e-fc2a01635862 2024-05-19T07:33:36+00:00 Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland Garde, Adam A. Søndergaard, Anne Sofie Guvad, Carsten Dahl-Møller, Jette Nehrke, Gernot Sanei, Hamed Weikusat, Christian Funder, Svend Kjær, Kurt H. Larsen, Nicolaj Krog 2020 application/pdf https://curis.ku.dk/portal/da/publications/pleistocene-organic-matter-modified-by-the-hiawatha-impact-northwest-greenland(9a0d5622-09b6-4fa4-b39e-fc2a01635862).html https://doi.org/10.1130/G47432.1 https://curis.ku.dk/ws/files/288731715/Pleistocene_organic_matter_modified_by_the_Hiawatha_impact_northwest_Greenland_publisher_version_.pdf eng eng info:eu-repo/semantics/openAccess Garde , A A , Søndergaard , A S , Guvad , C , Dahl-Møller , J , Nehrke , G , Sanei , H , Weikusat , C , Funder , S , Kjær , K H & Larsen , N K 2020 , ' Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland ' , Geology , vol. 48 , no. 9 , pp. 867-871 . https://doi.org/10.1130/G47432.1 article 2020 ftcopenhagenunip https://doi.org/10.1130/G47432.1 2024-05-02T00:33:11Z The 31-km-wide Hiawatha impact crater was recently discovered under the ice sheet in northwest Greenland, but its age remains uncertain. Here we investigate solid organic matter found at the tip of the Hiawatha Glacier to determine its thermal degradation, provenance, and age, and hence a maximum age of the impact. Impactite grains of microbrecchia and shock-melted glass in glaciofluvial sand contain abundant dispersed carbon, and gravel-sized charcoal particles are common on the outwash plain in front of the crater. The organic matter is depleted in the thermally sensitive, labile bio-macromolecule protohydrocarbons. Pebble-sized lumps of lignite collected close to the sand sample consist largely of fragments of conifers such as Pinus or Picea, with greatly expanded cork cells and desiccation cracks which suggest rapid, heat-induced expansion and contraction. Pinus and Picea are today extinct from North Greenland but are known from late Pliocene deposits in the Canadian Arctic Archipelago and early Pleistocene deposits at Kap Kobenhavn in eastern North Greenland. The thermally degraded organic material yields a maximum age for the impact, providing the first firm evidence that the Hiawatha crater is the youngest known large impact structure on Earth. Article in Journal/Newspaper Arctic Archipelago Arctic Canadian Arctic Archipelago glacier Greenland Ice Sheet North Greenland University of Copenhagen: Research Geology 48 9 867 871 |
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Open Polar |
collection |
University of Copenhagen: Research |
op_collection_id |
ftcopenhagenunip |
language |
English |
description |
The 31-km-wide Hiawatha impact crater was recently discovered under the ice sheet in northwest Greenland, but its age remains uncertain. Here we investigate solid organic matter found at the tip of the Hiawatha Glacier to determine its thermal degradation, provenance, and age, and hence a maximum age of the impact. Impactite grains of microbrecchia and shock-melted glass in glaciofluvial sand contain abundant dispersed carbon, and gravel-sized charcoal particles are common on the outwash plain in front of the crater. The organic matter is depleted in the thermally sensitive, labile bio-macromolecule protohydrocarbons. Pebble-sized lumps of lignite collected close to the sand sample consist largely of fragments of conifers such as Pinus or Picea, with greatly expanded cork cells and desiccation cracks which suggest rapid, heat-induced expansion and contraction. Pinus and Picea are today extinct from North Greenland but are known from late Pliocene deposits in the Canadian Arctic Archipelago and early Pleistocene deposits at Kap Kobenhavn in eastern North Greenland. The thermally degraded organic material yields a maximum age for the impact, providing the first firm evidence that the Hiawatha crater is the youngest known large impact structure on Earth. |
format |
Article in Journal/Newspaper |
author |
Garde, Adam A. Søndergaard, Anne Sofie Guvad, Carsten Dahl-Møller, Jette Nehrke, Gernot Sanei, Hamed Weikusat, Christian Funder, Svend Kjær, Kurt H. Larsen, Nicolaj Krog |
spellingShingle |
Garde, Adam A. Søndergaard, Anne Sofie Guvad, Carsten Dahl-Møller, Jette Nehrke, Gernot Sanei, Hamed Weikusat, Christian Funder, Svend Kjær, Kurt H. Larsen, Nicolaj Krog Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland |
author_facet |
Garde, Adam A. Søndergaard, Anne Sofie Guvad, Carsten Dahl-Møller, Jette Nehrke, Gernot Sanei, Hamed Weikusat, Christian Funder, Svend Kjær, Kurt H. Larsen, Nicolaj Krog |
author_sort |
Garde, Adam A. |
title |
Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland |
title_short |
Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland |
title_full |
Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland |
title_fullStr |
Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland |
title_full_unstemmed |
Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland |
title_sort |
pleistocene organic matter modified by the hiawatha impact, northwest greenland |
publishDate |
2020 |
url |
https://curis.ku.dk/portal/da/publications/pleistocene-organic-matter-modified-by-the-hiawatha-impact-northwest-greenland(9a0d5622-09b6-4fa4-b39e-fc2a01635862).html https://doi.org/10.1130/G47432.1 https://curis.ku.dk/ws/files/288731715/Pleistocene_organic_matter_modified_by_the_Hiawatha_impact_northwest_Greenland_publisher_version_.pdf |
genre |
Arctic Archipelago Arctic Canadian Arctic Archipelago glacier Greenland Ice Sheet North Greenland |
genre_facet |
Arctic Archipelago Arctic Canadian Arctic Archipelago glacier Greenland Ice Sheet North Greenland |
op_source |
Garde , A A , Søndergaard , A S , Guvad , C , Dahl-Møller , J , Nehrke , G , Sanei , H , Weikusat , C , Funder , S , Kjær , K H & Larsen , N K 2020 , ' Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland ' , Geology , vol. 48 , no. 9 , pp. 867-871 . https://doi.org/10.1130/G47432.1 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1130/G47432.1 |
container_title |
Geology |
container_volume |
48 |
container_issue |
9 |
container_start_page |
867 |
op_container_end_page |
871 |
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1799471716426055680 |