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Evidence for ca. 1 Ga hypervelocity impact event found in northwest Greenland

Hyde, William R. LU orcid ; Kenny, Gavin G. ; Jaret, Steven J. ; MacGregor, Joseph A. ; Beck, Pierre ; Whitehouse, Martin J. and Larsen, Nicolaj K. LU (2024) In Geology 52(7). p.517-521
Abstract

There are likely many undiscovered impact structures on Earth, but several challenges prevent their detection, including possible concealment beneath large ice sheets. In recent years, geophysical, geochemical, and microphysical evidence has mounted for a ca. 58 Ma impact structure under the Hiawatha Glacier, northwest Greenland. Here, we report evidence for a second, much older hypervelocity impact event in this region, recorded in an impact melt rock sample collected from a glaciofluvial deposit in Inglefield Land. Secondary ion mass spectrometry U-Pb analyses of shock metamorphosed zircon grains yielded a previously unrecorded, Proterozoic best estimate impact age of 1039 ± 16 Ma (mean square of weighted deviates = 2.9). Based on... (More)

There are likely many undiscovered impact structures on Earth, but several challenges prevent their detection, including possible concealment beneath large ice sheets. In recent years, geophysical, geochemical, and microphysical evidence has mounted for a ca. 58 Ma impact structure under the Hiawatha Glacier, northwest Greenland. Here, we report evidence for a second, much older hypervelocity impact event in this region, recorded in an impact melt rock sample collected from a glaciofluvial deposit in Inglefield Land. Secondary ion mass spectrometry U-Pb analyses of shock metamorphosed zircon grains yielded a previously unrecorded, Proterozoic best estimate impact age of 1039 ± 16 Ma (mean square of weighted deviates = 2.9). Based on Archean–Proterozoic target rock U-Pb ages obtained from unshocked zircon grains and the location of the melt rock sample along the ice margin, we suggest this sample was derived from a hypervelocity impact structure farther inland, concealed by the Greenland Ice Sheet. This study demonstrates the ability to uncover new impact events in some of the most inaccessible areas on Earth and the possibility of sampling multiple impact structures from one location when examining ex situ material. Our results have implications for current and future Martian and lunar returned samples that demonstrably bear complex impact histories.

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author
; ; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Greenland, Impact, Zircon, Shock
in
Geology
volume
52
issue
7
pages
5 pages
publisher
Geological Society of America
external identifiers
  • scopus:85200407603
ISSN
0091-7613
DOI
10.1130/G51876.1
language
English
LU publication?
no
id
0d214c3b-fa4f-4eda-9f96-05fd4b63ebd8
date added to LUP
2024-07-01 09:28:32
date last changed
2024-08-29 14:59:43
@article{0d214c3b-fa4f-4eda-9f96-05fd4b63ebd8,
  abstract     = {{<p>There are likely many undiscovered impact structures on Earth, but several challenges prevent their detection, including possible concealment beneath large ice sheets. In recent years, geophysical, geochemical, and microphysical evidence has mounted for a ca. 58 Ma impact structure under the Hiawatha Glacier, northwest Greenland. Here, we report evidence for a second, much older hypervelocity impact event in this region, recorded in an impact melt rock sample collected from a glaciofluvial deposit in Inglefield Land. Secondary ion mass spectrometry U-Pb analyses of shock metamorphosed zircon grains yielded a previously unrecorded, Proterozoic best estimate impact age of 1039 ± 16 Ma (mean square of weighted deviates = 2.9). Based on Archean–Proterozoic target rock U-Pb ages obtained from unshocked zircon grains and the location of the melt rock sample along the ice margin, we suggest this sample was derived from a hypervelocity impact structure farther inland, concealed by the Greenland Ice Sheet. This study demonstrates the ability to uncover new impact events in some of the most inaccessible areas on Earth and the possibility of sampling multiple impact structures from one location when examining ex situ material. Our results have implications for current and future Martian and lunar returned samples that demonstrably bear complex impact histories.</p>}},
  author       = {{Hyde, William R. and Kenny, Gavin G. and Jaret, Steven J. and MacGregor, Joseph A. and Beck, Pierre and Whitehouse, Martin J. and Larsen, Nicolaj K.}},
  issn         = {{0091-7613}},
  keywords     = {{Greenland; Impact; Zircon; Shock}},
  language     = {{eng}},
  number       = {{7}},
  pages        = {{517--521}},
  publisher    = {{Geological Society of America}},
  series       = {{Geology}},
  title        = {{Evidence for ca. 1 Ga hypervelocity impact event found in northwest Greenland}},
  url          = {{http://dx.doi.org/10.1130/G51876.1}},
  doi          = {{10.1130/G51876.1}},
  volume       = {{52}},
  year         = {{2024}},
}