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A Late Paleocene age for Greenland's Hiawatha impact structure

Kenny, Gavin G. ; Hyde, William R. LU orcid ; Storey, Michael ; Garde, Adam A. ; Whitehouse, Martin J. ; Beck, Pierre ; Johansson, Leif LU ; Søndergaard, Anne Sofie ; Bjørk, Anders A. and MacGregor, Joseph A. , et al. (2022) In Science Advances 8(10).
Abstract

The ~31-km-wide Hiawatha structure, located beneath Hiawatha Glacier in northwestern Greenland, has been proposed as an impact structure that may have formed after the Pleistocene inception of the Greenland Ice Sheet. To date the structure, we conducted 40Ar/39Ar analyses on glaciofluvial sand and U-Pb analyses on zircon separated from glaciofluvial pebbles of impact melt rock, all sampled immediately downstream of Hiawatha Glacier. Unshocked zircon in the impact melt rocks dates to ~1915 million years (Ma), consistent with felsic intrusions found in local bedrock. The 40Ar/39Ar data indicate Late Paleocene resetting and shocked zircon dates to 57.99 ± 0.54 Ma, which we interpret as the impact... (More)

The ~31-km-wide Hiawatha structure, located beneath Hiawatha Glacier in northwestern Greenland, has been proposed as an impact structure that may have formed after the Pleistocene inception of the Greenland Ice Sheet. To date the structure, we conducted 40Ar/39Ar analyses on glaciofluvial sand and U-Pb analyses on zircon separated from glaciofluvial pebbles of impact melt rock, all sampled immediately downstream of Hiawatha Glacier. Unshocked zircon in the impact melt rocks dates to ~1915 million years (Ma), consistent with felsic intrusions found in local bedrock. The 40Ar/39Ar data indicate Late Paleocene resetting and shocked zircon dates to 57.99 ± 0.54 Ma, which we interpret as the impact age. Consequently, the Hiawatha impact structure far predates Pleistocene glaciation and is unrelated to either the Paleocene-Eocene Thermal Maximum or flood basalt volcanism in east Greenland. However, it was contemporaneous with the Paleocene Carbon Isotope Maximum, although the impact's exact paleoenvironmental and climatic significance awaits further investigation.

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type
Contribution to journal
publication status
published
subject
in
Science Advances
volume
8
issue
10
article number
eabm2434
publisher
American Association for the Advancement of Science (AAAS)
external identifiers
  • pmid:35263140
  • scopus:85126080454
ISSN
2375-2548
DOI
10.1126/sciadv.abm2434
language
English
LU publication?
yes
id
ed6adca1-c61b-486d-8e06-ad3e5fac8130
date added to LUP
2022-04-20 12:26:54
date last changed
2025-01-28 07:47:29
@article{ed6adca1-c61b-486d-8e06-ad3e5fac8130,
  abstract     = {{<p>The ~31-km-wide Hiawatha structure, located beneath Hiawatha Glacier in northwestern Greenland, has been proposed as an impact structure that may have formed after the Pleistocene inception of the Greenland Ice Sheet. To date the structure, we conducted <sup>40</sup>Ar/<sup>39</sup>Ar analyses on glaciofluvial sand and U-Pb analyses on zircon separated from glaciofluvial pebbles of impact melt rock, all sampled immediately downstream of Hiawatha Glacier. Unshocked zircon in the impact melt rocks dates to ~1915 million years (Ma), consistent with felsic intrusions found in local bedrock. The <sup>40</sup>Ar/<sup>39</sup>Ar data indicate Late Paleocene resetting and shocked zircon dates to 57.99 ± 0.54 Ma, which we interpret as the impact age. Consequently, the Hiawatha impact structure far predates Pleistocene glaciation and is unrelated to either the Paleocene-Eocene Thermal Maximum or flood basalt volcanism in east Greenland. However, it was contemporaneous with the Paleocene Carbon Isotope Maximum, although the impact's exact paleoenvironmental and climatic significance awaits further investigation.</p>}},
  author       = {{Kenny, Gavin G. and Hyde, William R. and Storey, Michael and Garde, Adam A. and Whitehouse, Martin J. and Beck, Pierre and Johansson, Leif and Søndergaard, Anne Sofie and Bjørk, Anders A. and MacGregor, Joseph A. and Khan, Shfaqat A. and Mouginot, Jérémie and Johnson, Brandon C. and Silber, Elizabeth A. and Wielandt, Daniel K.P. and Kjær, Kurt H. and Larsen, Nicolaj K.}},
  issn         = {{2375-2548}},
  language     = {{eng}},
  number       = {{10}},
  publisher    = {{American Association for the Advancement of Science (AAAS)}},
  series       = {{Science Advances}},
  title        = {{A Late Paleocene age for Greenland's Hiawatha impact structure}},
  url          = {{http://dx.doi.org/10.1126/sciadv.abm2434}},
  doi          = {{10.1126/sciadv.abm2434}},
  volume       = {{8}},
  year         = {{2022}},
}