Geophysical constraints on the properties of a subglacial lake in northwest Greenland
<p>In this study, we report the results of an active-source seismology and ground-penetrating radar survey performed in northwestern Greenland at a site where the presence of a subglacial lake beneath the accumulation area has previously been proposed. Both seismic and radar results show a fla...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-07-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/15/3279/2021/tc-15-3279-2021.pdf |
| _version_ | 1818624324468211712 |
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| author | R. Maguire R. Maguire N. Schmerr E. Pettit K. Riverman C. Gardner D. N. DellaGiustina B. Avenson N. Wagner A. G. Marusiak N. Habib J. I. Broadbeck V. J. Bray S. H. Bailey |
| author_facet | R. Maguire R. Maguire N. Schmerr E. Pettit K. Riverman C. Gardner D. N. DellaGiustina B. Avenson N. Wagner A. G. Marusiak N. Habib J. I. Broadbeck V. J. Bray S. H. Bailey |
| author_sort | R. Maguire |
| collection | DOAJ |
| description | <p>In this study, we report the results of an active-source seismology and
ground-penetrating radar survey performed in northwestern Greenland at a
site where the presence of a subglacial lake beneath the accumulation area
has previously been proposed. Both seismic and radar results show a flat
reflector approximately 830–845 m below the surface, with a seismic
reflection coefficient of <span class="inline-formula">−0.43</span> <span class="inline-formula">±</span> 0.17, which is consistent with the
acoustic impedance contrast between a layer of water and glacial ice.
Additionally, in the seismic data we observe an intermittent lake bottom
reflection arriving between 14–20 ms after the lake top reflection,
corresponding to a lake depth of approximately 10–15 m. A strong coda
following the lake top and lake bottom reflections is consistent with a
package of lake bottom sediments although its thickness and material
properties are uncertain. Finally, we use these results to conduct a
first-order assessment of the lake origins using a one-dimensional thermal
model and hydropotential modeling based on published surface and bed
topography. Using these analyses, we narrow the lake origin hypotheses to
either anomalously high geothermal flux or hypersalinity due to local
ancient evaporite. Because the origins are still unclear, this site provides
an intriguing opportunity for the first in situ sampling of a subglacial lake in
Greenland, which could better constrain mechanisms of subglacial lake
formation, evolution, and relative importance to glacial hydrology.</p> |
| first_indexed | 2024-12-16T18:55:09Z |
| format | Article |
| id | doaj.art-7adbe5c35e01492c9c07462c06db981a |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-16T18:55:09Z |
| publishDate | 2021-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-7adbe5c35e01492c9c07462c06db981a2022-12-21T22:20:34ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242021-07-01153279329110.5194/tc-15-3279-2021Geophysical constraints on the properties of a subglacial lake in northwest GreenlandR. Maguire0R. Maguire1N. Schmerr2E. Pettit3K. Riverman4C. Gardner5D. N. DellaGiustina6B. Avenson7N. Wagner8A. G. Marusiak9N. Habib10J. I. Broadbeck11V. J. Bray12S. H. Bailey13Department of Geology, University of Maryland, College Park, MD 20742, USADepartment of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, USADepartment of Geology, University of Maryland, College Park, MD 20742, USACollege of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503, USACourant Institute of Mathematical Sciences, New York University, New York, NY 10012 USADepartment of Geosciences, Utah State University, Logan, UT 84322-4505, USALunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USASilicon Audio Inc., Austin, Pflugerville, TX 78660, USADepartment of Geosciences, University of Alaska, Fairbanks, AK 99775, USADepartment of Geology, University of Maryland, College Park, MD 20742, USALunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USALunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USALunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USALunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USA<p>In this study, we report the results of an active-source seismology and ground-penetrating radar survey performed in northwestern Greenland at a site where the presence of a subglacial lake beneath the accumulation area has previously been proposed. Both seismic and radar results show a flat reflector approximately 830–845 m below the surface, with a seismic reflection coefficient of <span class="inline-formula">−0.43</span> <span class="inline-formula">±</span> 0.17, which is consistent with the acoustic impedance contrast between a layer of water and glacial ice. Additionally, in the seismic data we observe an intermittent lake bottom reflection arriving between 14–20 ms after the lake top reflection, corresponding to a lake depth of approximately 10–15 m. A strong coda following the lake top and lake bottom reflections is consistent with a package of lake bottom sediments although its thickness and material properties are uncertain. Finally, we use these results to conduct a first-order assessment of the lake origins using a one-dimensional thermal model and hydropotential modeling based on published surface and bed topography. Using these analyses, we narrow the lake origin hypotheses to either anomalously high geothermal flux or hypersalinity due to local ancient evaporite. Because the origins are still unclear, this site provides an intriguing opportunity for the first in situ sampling of a subglacial lake in Greenland, which could better constrain mechanisms of subglacial lake formation, evolution, and relative importance to glacial hydrology.</p>https://tc.copernicus.org/articles/15/3279/2021/tc-15-3279-2021.pdf |
| spellingShingle | R. Maguire R. Maguire N. Schmerr E. Pettit K. Riverman C. Gardner D. N. DellaGiustina B. Avenson N. Wagner A. G. Marusiak N. Habib J. I. Broadbeck V. J. Bray S. H. Bailey Geophysical constraints on the properties of a subglacial lake in northwest Greenland The Cryosphere |
| title | Geophysical constraints on the properties of a subglacial lake in northwest Greenland |
| title_full | Geophysical constraints on the properties of a subglacial lake in northwest Greenland |
| title_fullStr | Geophysical constraints on the properties of a subglacial lake in northwest Greenland |
| title_full_unstemmed | Geophysical constraints on the properties of a subglacial lake in northwest Greenland |
| title_short | Geophysical constraints on the properties of a subglacial lake in northwest Greenland |
| title_sort | geophysical constraints on the properties of a subglacial lake in northwest greenland |
| url | https://tc.copernicus.org/articles/15/3279/2021/tc-15-3279-2021.pdf |
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