Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland
Petermann Fjord is a deep (> 1000 m) fjord that incises the coastline of northwest Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5–70 m of unconsolidated glacigenic material infills in the...
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ftcopernicus:oai:publications.copernicus.org:tcd78623 2023-05-15T13:35:05+02:00 Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland Hogan, Kelly A. Jakobsson, Martin Mayer, Larry Reilly, Brendan Jennings, Anne Mix, Alan Nielsen, Tove Andresen, Katrine J. Nørmark, Egon Heirmann, Katrien A. Kamla, Elina Jerram, Kevin Stranne, Christian 2019-08-01 application/pdf https://doi.org/10.5194/tc-2019-171 https://www.the-cryosphere-discuss.net/tc-2019-171/ eng eng doi:10.5194/tc-2019-171 https://www.the-cryosphere-discuss.net/tc-2019-171/ eISSN: 1994-0424 Text 2019 ftcopernicus https://doi.org/10.5194/tc-2019-171 2019-12-24T09:48:45Z Petermann Fjord is a deep (> 1000 m) fjord that incises the coastline of northwest Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5–70 m of unconsolidated glacigenic material infills in the fjord and adjacent Nares Strait, deposited as the Petermann and Nares Strait ice streams retreated through the area after the Last Glacial Maximum. We have investigated the deglacial deposits using seismic stratigraphic techniques and have correlated our results with high-resolution bathymetric data and core lithofacies. We identify six seismo-acoustic facies in more than 3500 line-km of sub-bottom and seismic-reflection profiles throughout the fjord, Hall Basin and Kennedy Channel. Seismo-acoustic facies relate to: bedrock or till surfaces ( Facies I ); subglacial deposition ( Facies II ); deposition from meltwater plumes and icebergs in quiescent glaciomarine conditions ( Facies III, IV ); deposition at grounded ice margins during stillstands in retreat (grounding-zone wedges; Facies V ); and the redeposition of material down slopes ( Facies IV ). These sediment units represent the total volume of glacial sediment delivered to the mapped marine environment during retreat. We calculate a glacial sediment flux for the former Petermann Ice Stream as 1080–1420 m 3 a −1 per meter of ice stream width and an average deglacial erosion rate for the basin of 0.29–0.34 mm a −1 . Our deglacial erosion rates are consistent with results from Antarctic Peninsula fjord systems but are several times lower than values for other modern GrIS catchments. This difference is attributed to fact that large volumes of surface water do not access the bed in the Petermann system and we conclude that glacial erosion is limited to areas overridden by streaming ice in this large outlet glacier setting. Erosion rates are also presented for two phases of ice retreat and confirm that there is significant variation in these rates over a glacial-deglacial transition. Our new fluxes and erosion rates show that the Petermann Ice Stream was approximately as efficient as the palaeo-Jakobshavn Isbrae at eroding, transporting and delivering sediment to its margin during early deglaciation. Text Antarc* Antarctic Antarctic Peninsula glacier Greenland Hall Basin Ice Sheet Iceberg* Jakobshavn Kennedy channel Nares strait Petermann Fjord Petermann glacier Copernicus Publications: E-Journals Antarctic Antarctic Peninsula Greenland Hall Basin ENVELOPE(-62.992,-62.992,81.502,81.502) Kennedy Channel ENVELOPE(-66.139,-66.139,80.919,80.919) Nares ENVELOPE(158.167,158.167,-81.450,-81.450) Petermann Fjord ENVELOPE(-61.500,-61.500,81.167,81.167) |
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Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Petermann Fjord is a deep (> 1000 m) fjord that incises the coastline of northwest Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5–70 m of unconsolidated glacigenic material infills in the fjord and adjacent Nares Strait, deposited as the Petermann and Nares Strait ice streams retreated through the area after the Last Glacial Maximum. We have investigated the deglacial deposits using seismic stratigraphic techniques and have correlated our results with high-resolution bathymetric data and core lithofacies. We identify six seismo-acoustic facies in more than 3500 line-km of sub-bottom and seismic-reflection profiles throughout the fjord, Hall Basin and Kennedy Channel. Seismo-acoustic facies relate to: bedrock or till surfaces ( Facies I ); subglacial deposition ( Facies II ); deposition from meltwater plumes and icebergs in quiescent glaciomarine conditions ( Facies III, IV ); deposition at grounded ice margins during stillstands in retreat (grounding-zone wedges; Facies V ); and the redeposition of material down slopes ( Facies IV ). These sediment units represent the total volume of glacial sediment delivered to the mapped marine environment during retreat. We calculate a glacial sediment flux for the former Petermann Ice Stream as 1080–1420 m 3 a −1 per meter of ice stream width and an average deglacial erosion rate for the basin of 0.29–0.34 mm a −1 . Our deglacial erosion rates are consistent with results from Antarctic Peninsula fjord systems but are several times lower than values for other modern GrIS catchments. This difference is attributed to fact that large volumes of surface water do not access the bed in the Petermann system and we conclude that glacial erosion is limited to areas overridden by streaming ice in this large outlet glacier setting. Erosion rates are also presented for two phases of ice retreat and confirm that there is significant variation in these rates over a glacial-deglacial transition. Our new fluxes and erosion rates show that the Petermann Ice Stream was approximately as efficient as the palaeo-Jakobshavn Isbrae at eroding, transporting and delivering sediment to its margin during early deglaciation. |
format |
Text |
author |
Hogan, Kelly A. Jakobsson, Martin Mayer, Larry Reilly, Brendan Jennings, Anne Mix, Alan Nielsen, Tove Andresen, Katrine J. Nørmark, Egon Heirmann, Katrien A. Kamla, Elina Jerram, Kevin Stranne, Christian |
spellingShingle |
Hogan, Kelly A. Jakobsson, Martin Mayer, Larry Reilly, Brendan Jennings, Anne Mix, Alan Nielsen, Tove Andresen, Katrine J. Nørmark, Egon Heirmann, Katrien A. Kamla, Elina Jerram, Kevin Stranne, Christian Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland |
author_facet |
Hogan, Kelly A. Jakobsson, Martin Mayer, Larry Reilly, Brendan Jennings, Anne Mix, Alan Nielsen, Tove Andresen, Katrine J. Nørmark, Egon Heirmann, Katrien A. Kamla, Elina Jerram, Kevin Stranne, Christian |
author_sort |
Hogan, Kelly A. |
title |
Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland |
title_short |
Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland |
title_full |
Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland |
title_fullStr |
Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland |
title_full_unstemmed |
Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, NW Greenland |
title_sort |
glacial sedimentation, fluxes and erosion rates associated with ice retreat in petermann fjord and nares strait, nw greenland |
publishDate |
2019 |
url |
https://doi.org/10.5194/tc-2019-171 https://www.the-cryosphere-discuss.net/tc-2019-171/ |
long_lat |
ENVELOPE(-62.992,-62.992,81.502,81.502) ENVELOPE(-66.139,-66.139,80.919,80.919) ENVELOPE(158.167,158.167,-81.450,-81.450) ENVELOPE(-61.500,-61.500,81.167,81.167) |
geographic |
Antarctic Antarctic Peninsula Greenland Hall Basin Kennedy Channel Nares Petermann Fjord |
geographic_facet |
Antarctic Antarctic Peninsula Greenland Hall Basin Kennedy Channel Nares Petermann Fjord |
genre |
Antarc* Antarctic Antarctic Peninsula glacier Greenland Hall Basin Ice Sheet Iceberg* Jakobshavn Kennedy channel Nares strait Petermann Fjord Petermann glacier |
genre_facet |
Antarc* Antarctic Antarctic Peninsula glacier Greenland Hall Basin Ice Sheet Iceberg* Jakobshavn Kennedy channel Nares strait Petermann Fjord Petermann glacier |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-2019-171 https://www.the-cryosphere-discuss.net/tc-2019-171/ |
op_doi |
https://doi.org/10.5194/tc-2019-171 |
_version_ |
1766060825825509376 |