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Effect of ice sheet thickness on formation of the Hiawatha impact crater.

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Title: Effect of ice sheet thickness on formation of the Hiawatha impact crater.
Authors: Silber, Elizabeth A.1,2 (AUTHOR) esilber@uwo.ca, Johnson, Brandon C.3,4 (AUTHOR), Bjonnes, Evan5 (AUTHOR), MacGregor, Joseph A.6 (AUTHOR), Larsen, Nicolaj K.7 (AUTHOR), Wiggins, Sean E.3 (AUTHOR)
Source: Earth & Planetary Science Letters. Jul2021, Vol. 566, pN.PAG-N.PAG. 1p.
Subjects: Ice sheets, Greenland ice, Drill cores, Ice cores, Impact craters, Drill core analysis
Geographic Terms: Greenland
Abstract: • Hiawatha is a 31 km wide putative impact crater found below the Greenland Ice Sheet. • The impact should produce a trace of distal rocky ejecta in drill core samples. • iSALE hydrocode used to study the crater morphology and emplacement of rocky ejecta. • The presence of an ice sheet inhibits ejection of rocky material. • The putative Hiawatha crater likely formed in the last 2.6 Myr. The discovery of a large putative impact crater buried beneath Hiawatha Glacier along the margin of the northwestern Greenland Ice Sheet has reinvigorated interest into the nature of large impacts into thick ice masses. This circular structure is relatively shallow and exhibits a small central uplift, whereas a peak-ring morphology is expected. This discrepancy may be due to long-term and ongoing subglacial erosion but may also be explained by a relatively recent impact through the Greenland Ice Sheet, which is expected to alter the final crater morphology. Here we model crater formation using hydrocode simulations, varying pre-impact ice thickness and impactor composition over crystalline target rock. We find that an ice-sheet thickness of 1.5 or 2 km results in a crater morphology that is consistent with the present morphology of this structure. Further, an ice sheet that thick substantially inhibits ejection of rocky material, which might explain the absence of rocky ejecta in most existing Greenland deep ice cores if the impact occurred during the late Pleistocene. From the present morphology of the putative Hiawatha impact crater alone, we cannot distinguish between an older crater formed by a pre-Pleistocene impact into ice-free bedrock or a younger, Pleistocene impact into locally thick ice, but based on our modeling we conclude that latter scenario is possible. [ABSTRACT FROM AUTHOR]
Copyright of Earth & Planetary Science Letters is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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DbLabel: Engineering Source
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PubType: Academic Journal
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  Data: Effect of ice sheet thickness on formation of the Hiawatha impact crater.
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  Data: <searchLink fieldCode="AR" term="%22Silber%2C+Elizabeth+A%2E%22">Silber, Elizabeth A.</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> esilber@uwo.ca</i><br /><searchLink fieldCode="AR" term="%22Johnson%2C+Brandon+C%2E%22">Johnson, Brandon C.</searchLink><relatesTo>3,4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Bjonnes%2C+Evan%22">Bjonnes, Evan</searchLink><relatesTo>5</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22MacGregor%2C+Joseph+A%2E%22">MacGregor, Joseph A.</searchLink><relatesTo>6</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Larsen%2C+Nicolaj+K%2E%22">Larsen, Nicolaj K.</searchLink><relatesTo>7</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Wiggins%2C+Sean+E%2E%22">Wiggins, Sean E.</searchLink><relatesTo>3</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Earth+%26+Planetary+Science+Letters%22">Earth & Planetary Science Letters</searchLink>. Jul2021, Vol. 566, pN.PAG-N.PAG. 1p.
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  Data: <searchLink fieldCode="DE" term="%22Ice+sheets%22">Ice sheets</searchLink><br /><searchLink fieldCode="DE" term="%22Greenland+ice%22">Greenland ice</searchLink><br /><searchLink fieldCode="DE" term="%22Drill+cores%22">Drill cores</searchLink><br /><searchLink fieldCode="DE" term="%22Ice+cores%22">Ice cores</searchLink><br /><searchLink fieldCode="DE" term="%22Impact+craters%22">Impact craters</searchLink><br /><searchLink fieldCode="DE" term="%22Drill+core+analysis%22">Drill core analysis</searchLink>
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  Data: <searchLink fieldCode="DE" term="%22Greenland%22">Greenland</searchLink>
– Name: Abstract
  Label: Abstract
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  Data: • Hiawatha is a 31 km wide putative impact crater found below the Greenland Ice Sheet. • The impact should produce a trace of distal rocky ejecta in drill core samples. • iSALE hydrocode used to study the crater morphology and emplacement of rocky ejecta. • The presence of an ice sheet inhibits ejection of rocky material. • The putative Hiawatha crater likely formed in the last 2.6 Myr. The discovery of a large putative impact crater buried beneath Hiawatha Glacier along the margin of the northwestern Greenland Ice Sheet has reinvigorated interest into the nature of large impacts into thick ice masses. This circular structure is relatively shallow and exhibits a small central uplift, whereas a peak-ring morphology is expected. This discrepancy may be due to long-term and ongoing subglacial erosion but may also be explained by a relatively recent impact through the Greenland Ice Sheet, which is expected to alter the final crater morphology. Here we model crater formation using hydrocode simulations, varying pre-impact ice thickness and impactor composition over crystalline target rock. We find that an ice-sheet thickness of 1.5 or 2 km results in a crater morphology that is consistent with the present morphology of this structure. Further, an ice sheet that thick substantially inhibits ejection of rocky material, which might explain the absence of rocky ejecta in most existing Greenland deep ice cores if the impact occurred during the late Pleistocene. From the present morphology of the putative Hiawatha impact crater alone, we cannot distinguish between an older crater formed by a pre-Pleistocene impact into ice-free bedrock or a younger, Pleistocene impact into locally thick ice, but based on our modeling we conclude that latter scenario is possible. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Earth & Planetary Science Letters is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
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    Identifiers:
      – Type: doi
        Value: 10.1016/j.epsl.2021.116972
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      – Code: eng
        Text: English
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      Pagination:
        PageCount: 1
        StartPage: N.PAG
    Subjects:
      – SubjectFull: Ice sheets
        Type: general
      – SubjectFull: Greenland ice
        Type: general
      – SubjectFull: Drill cores
        Type: general
      – SubjectFull: Ice cores
        Type: general
      – SubjectFull: Impact craters
        Type: general
      – SubjectFull: Drill core analysis
        Type: general
      – SubjectFull: Greenland
        Type: general
    Titles:
      – TitleFull: Effect of ice sheet thickness on formation of the Hiawatha impact crater.
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            NameFull: MacGregor, Joseph A.
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            NameFull: Larsen, Nicolaj K.
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              M: 07
              Text: Jul2021
              Type: published
              Y: 2021
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              Value: 566
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