Geophysical constraints on the properties of a subglacial lake in northwest Greenland
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 reflect...
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ftcopernicus:oai:publications.copernicus.org:tc90723 2023-05-15T16:27:11+02:00 Geophysical constraints on the properties of a subglacial lake in northwest Greenland Maguire, Ross Schmerr, Nicholas Pettit, Erin Riverman, Kiya Gardner, Christyna DellaGiustina, Daniella N. Avenson, Brad Wagner, Natalie Marusiak, Angela G. Habib, Namrah Broadbeck, Juliette I. Bray, Veronica J. Bailey, Samuel H. 2021-07-16 application/pdf https://doi.org/10.5194/tc-15-3279-2021 https://tc.copernicus.org/articles/15/3279/2021/ eng eng doi:10.5194/tc-15-3279-2021 https://tc.copernicus.org/articles/15/3279/2021/ eISSN: 1994-0424 Text 2021 ftcopernicus https://doi.org/10.5194/tc-15-3279-2021 2021-07-19T16:22:26Z 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 −0.43 ± 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. Text Greenland Copernicus Publications: E-Journals Greenland The Cryosphere 15 7 3279 3291 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
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 −0.43 ± 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. |
format |
Text |
author |
Maguire, Ross Schmerr, Nicholas Pettit, Erin Riverman, Kiya Gardner, Christyna DellaGiustina, Daniella N. Avenson, Brad Wagner, Natalie Marusiak, Angela G. Habib, Namrah Broadbeck, Juliette I. Bray, Veronica J. Bailey, Samuel H. |
spellingShingle |
Maguire, Ross Schmerr, Nicholas Pettit, Erin Riverman, Kiya Gardner, Christyna DellaGiustina, Daniella N. Avenson, Brad Wagner, Natalie Marusiak, Angela G. Habib, Namrah Broadbeck, Juliette I. Bray, Veronica J. Bailey, Samuel H. Geophysical constraints on the properties of a subglacial lake in northwest Greenland |
author_facet |
Maguire, Ross Schmerr, Nicholas Pettit, Erin Riverman, Kiya Gardner, Christyna DellaGiustina, Daniella N. Avenson, Brad Wagner, Natalie Marusiak, Angela G. Habib, Namrah Broadbeck, Juliette I. Bray, Veronica J. Bailey, Samuel H. |
author_sort |
Maguire, Ross |
title |
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_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_sort |
geophysical constraints on the properties of a subglacial lake in northwest greenland |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-3279-2021 https://tc.copernicus.org/articles/15/3279/2021/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-15-3279-2021 https://tc.copernicus.org/articles/15/3279/2021/ |
op_doi |
https://doi.org/10.5194/tc-15-3279-2021 |
container_title |
The Cryosphere |
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15 |
container_issue |
7 |
container_start_page |
3279 |
op_container_end_page |
3291 |
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