Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica
© 2019, © 2019 Australian Society of Exploration Geophysicists. Permafrost is ubiquitous at high latitudes, and its thickness is controlled by important local factors like geothermal flux, ground surface temperature and thermal properties of the subsurface. We use airborne transient electromagnetic...
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ftlouisianastuir:oai:digitalcommons.lsu.edu:geo_pubs-1582 2023-06-11T04:04:39+02:00 Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica Foley, Neil Tulaczyk, Slawomir Auken, Esben Grombacher, Denys Mikucki, Jill Foged, Nikolaj Myers, Krista Dugan, Hilary Doran, Peter T. Virginia, Ross A. 2020-01-02T08:00:00Z https://digitalcommons.lsu.edu/geo_pubs/583 https://doi.org/10.1080/08123985.2019.1651618 unknown LSU Digital Commons https://digitalcommons.lsu.edu/geo_pubs/583 doi:10.1080/08123985.2019.1651618 Faculty Publications Antarctica electrical resistivity Geothermal flux permafrost text 2020 ftlouisianastuir https://doi.org/10.1080/08123985.2019.1651618 2023-05-28T18:16:59Z © 2019, © 2019 Australian Society of Exploration Geophysicists. Permafrost is ubiquitous at high latitudes, and its thickness is controlled by important local factors like geothermal flux, ground surface temperature and thermal properties of the subsurface. We use airborne transient electromagnetic resistivity measurements to determine permafrost thickness on the coast of Ross Island, Antarctica, which contains the active volcano Mt Erebus. Here, resistivity data clearly distinguish resistive permafrost from the electrically conductive fluid-saturated materials underlying it. For our study, we define permafrost as frozen material with a resistivity > 100 Ω·m; more conductive material contains a significant fraction of water or (more likely) brine. We observe that permafrost is very thin near the coast and thickens within several hundred metres inland to reach depths that are typically within the range of 300–400 m. We attribute the sharp near-shore increase in permafrost thickness to lateral heat conduction from the relatively warm ocean, possibly combined with seawater infiltration into the near-shore permafrost. We validate this result with a two-dimensional heat flow model and conclude that away from the thermal influence of the ocean, the local geothermal gradient and heat flux are about 45 ± 5 °C/km and 90 ± 13 mW/m2, respectively. These values are in line with published estimates in the vicinity of Mt Erebus and within the actively extending Terror Rift, but do not reflect a strong heat flow anomaly from volcanic activity of Mt Erebus. Measurements made previously in the McMurdo Dry Valleys, on the other side of McMurdo Sound, tend to be a few dozens of mW/m2 lower, likely reflecting its different tectonic setting on the uplifted rift shoulder of Transantarctic Mountains. Our study demonstrates a new approach towards constraining geothermal flux in polar regions using airborne electromagnetic (AEM) data that can be relatively efficiently collected on regional scales where ice coverage does not exceed ... Text Antarc* Antarctica Ice McMurdo Dry Valleys McMurdo Sound permafrost Ross Island LSU Digital Commons (Louisiana State University) McMurdo Dry Valleys McMurdo Sound Ross Island Transantarctic Mountains Exploration Geophysics 51 1 84 93 |
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Open Polar |
collection |
LSU Digital Commons (Louisiana State University) |
op_collection_id |
ftlouisianastuir |
language |
unknown |
topic |
Antarctica electrical resistivity Geothermal flux permafrost |
spellingShingle |
Antarctica electrical resistivity Geothermal flux permafrost Foley, Neil Tulaczyk, Slawomir Auken, Esben Grombacher, Denys Mikucki, Jill Foged, Nikolaj Myers, Krista Dugan, Hilary Doran, Peter T. Virginia, Ross A. Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica |
topic_facet |
Antarctica electrical resistivity Geothermal flux permafrost |
description |
© 2019, © 2019 Australian Society of Exploration Geophysicists. Permafrost is ubiquitous at high latitudes, and its thickness is controlled by important local factors like geothermal flux, ground surface temperature and thermal properties of the subsurface. We use airborne transient electromagnetic resistivity measurements to determine permafrost thickness on the coast of Ross Island, Antarctica, which contains the active volcano Mt Erebus. Here, resistivity data clearly distinguish resistive permafrost from the electrically conductive fluid-saturated materials underlying it. For our study, we define permafrost as frozen material with a resistivity > 100 Ω·m; more conductive material contains a significant fraction of water or (more likely) brine. We observe that permafrost is very thin near the coast and thickens within several hundred metres inland to reach depths that are typically within the range of 300–400 m. We attribute the sharp near-shore increase in permafrost thickness to lateral heat conduction from the relatively warm ocean, possibly combined with seawater infiltration into the near-shore permafrost. We validate this result with a two-dimensional heat flow model and conclude that away from the thermal influence of the ocean, the local geothermal gradient and heat flux are about 45 ± 5 °C/km and 90 ± 13 mW/m2, respectively. These values are in line with published estimates in the vicinity of Mt Erebus and within the actively extending Terror Rift, but do not reflect a strong heat flow anomaly from volcanic activity of Mt Erebus. Measurements made previously in the McMurdo Dry Valleys, on the other side of McMurdo Sound, tend to be a few dozens of mW/m2 lower, likely reflecting its different tectonic setting on the uplifted rift shoulder of Transantarctic Mountains. Our study demonstrates a new approach towards constraining geothermal flux in polar regions using airborne electromagnetic (AEM) data that can be relatively efficiently collected on regional scales where ice coverage does not exceed ... |
format |
Text |
author |
Foley, Neil Tulaczyk, Slawomir Auken, Esben Grombacher, Denys Mikucki, Jill Foged, Nikolaj Myers, Krista Dugan, Hilary Doran, Peter T. Virginia, Ross A. |
author_facet |
Foley, Neil Tulaczyk, Slawomir Auken, Esben Grombacher, Denys Mikucki, Jill Foged, Nikolaj Myers, Krista Dugan, Hilary Doran, Peter T. Virginia, Ross A. |
author_sort |
Foley, Neil |
title |
Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica |
title_short |
Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica |
title_full |
Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica |
title_fullStr |
Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica |
title_full_unstemmed |
Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica |
title_sort |
mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of ross island, antarctica |
publisher |
LSU Digital Commons |
publishDate |
2020 |
url |
https://digitalcommons.lsu.edu/geo_pubs/583 https://doi.org/10.1080/08123985.2019.1651618 |
geographic |
McMurdo Dry Valleys McMurdo Sound Ross Island Transantarctic Mountains |
geographic_facet |
McMurdo Dry Valleys McMurdo Sound Ross Island Transantarctic Mountains |
genre |
Antarc* Antarctica Ice McMurdo Dry Valleys McMurdo Sound permafrost Ross Island |
genre_facet |
Antarc* Antarctica Ice McMurdo Dry Valleys McMurdo Sound permafrost Ross Island |
op_source |
Faculty Publications |
op_relation |
https://digitalcommons.lsu.edu/geo_pubs/583 doi:10.1080/08123985.2019.1651618 |
op_doi |
https://doi.org/10.1080/08123985.2019.1651618 |
container_title |
Exploration Geophysics |
container_volume |
51 |
container_issue |
1 |
container_start_page |
84 |
op_container_end_page |
93 |
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1768389577367617536 |