Hiawatha Glacier

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Hiawatha Glacier
Hiawatha Glacier.jpg
Land-terminating Hiawatha Glacier (left-center) emerging from its semicircular parent ice lobe, in NW Greenland
Coordinates78°49′N 67°01′W / 78.817°N 67.017°W / 78.817; -67.017Coordinates: 78°49′N 67°01′W / 78.817°N 67.017°W / 78.817; -67.017

Hiawatha Glacier is a glacier in northwest Greenland, near Inglefield Land.[1][2] It was mapped in 1922 by Lauge Koch, who noted that the glacier tongue extended into Lake Alida (near Foulk Fjord).[3] Hiawatha Glacier attracted attention in 2018 because of the discovery of a crater beneath the surface of the ice sheet in the area.[4] A publication noted in 1952 that Hiawatha Glacier had been retreating since 1920.[5]

Impact structure[edit]

Two views of the Hiawatha crater region—one covered by the Greenland Ice Sheet, the other showing the topography of the rock beneath the ice sheet, including the crater
Hiawatha Glacier Crater
Hiawatha Crater
Hiawatha v45 scene1 4k 5mtopo.1760.tif
NASA digital elevation model with the ice sheet removed to show surface of bedrock in the region around the Hiawatha Glacier
Impact crater/structure
ConfidenceProbable
Diameter31 kilometers (19 mi)
Depth320 meters (1,050 ft)
Impactor diameter1.5 kilometers (0.9 mi)
Age57.99 ± 0.54 Ma, Late Paleocene
Exposedno
Drilledno
Bolide typeIron meteorite
Location
Coordinates78°44′N 66°14′W / 78.733°N 66.233°W / 78.733; -66.233
CountryGreenland
ProvinceAvannaata
Hiawatha Glacier Crater is located in Greenland
Hiawatha Glacier Crater
Hiawatha Glacier Crater
Accessnone

In November 2018, a study revealed the existence of a large (31-kilometre-wide [19 mi]) circular depression beneath Greenland's ice sheet in the Hiawatha Glacier region—up to a kilometre below the surface of the ice.[6] The bedrock within the region of this structure consists of 1.985 to 1.740 billion year old Paleoproterozoic felsic igneous rocks and paragneiss.[7]

From an interpretation of the crystalline nature of the underlying rock, together with chemical analysis of sediment washed from the crater, the impactor was argued to be a metallic asteroid with a diameter in the order of 1.5 kilometres (0.9 mi). A volume of approximately 20 cubic kilometres (4.8 cu mi) of rock would have been either vaporized or melted. Such an impact would have continued to melt ice flowing into the crater for an as-of-yet undetermined period post-impact. If an impact origin for the crater is confirmed, still to be done, it would be one of the twenty-five largest known impact craters on Earth.[6]

Shortly after the crater was discovered, researchers suggested that the impact could have occurred as late as ~12,800 years ago, leading some to associate it with the Younger Dryas impact hypothesis.[6] These claims were criticised by other scholars.[8][9]

A 2022 study using argon–argon dating combined with uranium–lead dating of shocked zircon crystals in impact melt rocks found in outwash less than 10 km downstream of the glacier pushed the estimate back to around 57.99 ± 0.54 million years ago, during the late Paleocene.[10][7] Confirmation would require drilling almost one km (3,300 ft) through the ice sheet above the crater to obtain a sample of dateable, solidified impact melt from the crater.

In February 2019, a NASA glaciologist discovered a possible second impact crater buried under ice in northwest Greenland. Though the newly found impact sites in northwest Greenland are only 183 km apart, at present they do not appear to have formed at the same time. If the second crater, which has a width of over 35 km, is ultimately confirmed as the result of a meteorite impact, it will be the 22nd largest impact crater found on Earth.[11]

See also[edit]

References[edit]

  1. ^ Dawes; et al. (2000). "Kane Basin 1999: mapping, stratigraphic studies and economic assessment of Precambrian and Lower Palaeozoic provinces in north-western Greenland". p. 11.
  2. ^ "Hiawatha Gletscher: Greenland". Geographical Names. Retrieved November 15, 2018.
  3. ^ Davies, William E.; Krinsley, Daniel B. (1962). "The recent regimen of the ice cap margin in North Greenland" (PDF). International Association of Scientific Hydrology, Commission of Snow and Ice. p. 124.
  4. ^ St. Fleur, Niocholas (November 14, 2018). "Ice Age Asteroid Crater Discovered Beneath Greenland Glacier - It is the first crater discovered under one of Earth's ice sheets, according to the scientists who found it". The New York Times. Retrieved November 18, 2018.
  5. ^ Børge Fristrup (1952). "Die Klimaänderungen in der Arktis und ihre Bedeutung besonders für Grönland". Erdkunde. 6 (4). doi:10.3112/erdkunde.1952.04.01.
  6. ^ a b c Kjær, Kurt H.; et al. (November 2018). "A large impact crater beneath Hiawatha Glacier in northwest Greenland". Science Advances. 4 (11): eaar8173. Bibcode:2018SciA....4.8173K. doi:10.1126/sciadv.aar8173. PMC 6235527. PMID 30443592.
  7. ^ a b Kenny, Gavin G.; Hyde, William R.; Storey, Michael; Garde, Adam A.; Whitehouse, Martin J.; Beck, Pierre; Johansson, Leif; Søndergaard, Anne Sofie; Bjørk, Anders A.; MacGregor, Joseph A.; Khan, Shfaqat A.; Mouginot, Jérémie; Johnson, Brandon C.; Silber, Elizabeth A.; Wielandt, Daniel K. P.; Kjær, Kurt H.; Larsen, Nicolaj K. (11 March 2022). "A Late Paleocene age for Greenland's Hiawatha impact structure". Science Advances. 8 (10): eabm2434. doi:10.1126/sciadv.abm2434.
  8. ^ Voosen P (14 November 2018). "Massive crater under Greenland's ice points to climate-altering impact in the time of humans". Sciencemag.org. Science. Archived from the original on 13 January 2019. Retrieved 13 January 2019.
  9. ^ Boslough M (March 2019). "Crater Discovery Story Flawed by Premature Link to Speculative Impact Hypothesis". Skeptical Inquirer. 43 (2): 6–7.
  10. ^ Copenhagen, University of (9 March 2022). "Giant impact crater in Greenland occurred a few million years after dinosaurs went extinct". phys.org. Archived from the original on 10 March 2022.
  11. ^ "NASA Finds 2nd Impact Crater Under Greenland Ice". 2019-02-07.

External links[edit]