Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams
Conceptual ice stream land systems derived from geomorphological and sedimentological observations provide constraints on ice–meltwater–till–bedrock interactions on palaeo-ice stream beds. Within these land systems, the spatial distribution and formation processes of ribbed bedforms remain unclear....
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ftcopernicus:oai:publications.copernicus.org:tc91040 2023-05-15T16:41:05+02:00 Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams Vérité, Jean Ravier, Édouard Bourgeois, Olivier Pochat, Stéphane Lelandais, Thomas Mourgues, Régis Clark, Christopher D. Bessin, Paul Peigné, David Atkinson, Nigel 2021-06-28 application/pdf https://doi.org/10.5194/tc-15-2889-2021 https://tc.copernicus.org/articles/15/2889/2021/ eng eng doi:10.5194/tc-15-2889-2021 https://tc.copernicus.org/articles/15/2889/2021/ eISSN: 1994-0424 Text 2021 ftcopernicus https://doi.org/10.5194/tc-15-2889-2021 2021-07-05T16:22:18Z Conceptual ice stream land systems derived from geomorphological and sedimentological observations provide constraints on ice–meltwater–till–bedrock interactions on palaeo-ice stream beds. Within these land systems, the spatial distribution and formation processes of ribbed bedforms remain unclear. We explore the conditions under which these bedforms may develop and their spatial organization with (i) an experimental model that reproduces the dynamics of ice streams and subglacial land systems and (ii) an analysis of the distribution of ribbed bedforms on selected examples of palaeo-ice stream beds of the Laurentide Ice Sheet. We find that a specific kind of ribbed bedform can develop subglacially through soft-bed deformation, where the ice flow undergoes lateral or longitudinal velocity gradients and the ice–bed interface is unlubricated; oblique ribbed bedforms develop beneath lateral shear margins, whereas transverse ribbed bedforms develop below frontal lobes. We infer that (i) ribbed bedforms strike orthogonally to the compressing axis of the horizontal strain ellipse of the ice surface and (ii) their development reveals distinctive types of subglacial drainage patterns: linked cavities below lateral shear margins and efficient meltwater channels below frontal lobes. These ribbed bedforms may act as convenient geomorphic markers to reconstruct lateral and frontal margins, constrain ice flow dynamics, and infer meltwater drainage characteristics of palaeo-ice streams. Text Ice Sheet Copernicus Publications: E-Journals The Cryosphere 15 6 2889 2916 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
Conceptual ice stream land systems derived from geomorphological and sedimentological observations provide constraints on ice–meltwater–till–bedrock interactions on palaeo-ice stream beds. Within these land systems, the spatial distribution and formation processes of ribbed bedforms remain unclear. We explore the conditions under which these bedforms may develop and their spatial organization with (i) an experimental model that reproduces the dynamics of ice streams and subglacial land systems and (ii) an analysis of the distribution of ribbed bedforms on selected examples of palaeo-ice stream beds of the Laurentide Ice Sheet. We find that a specific kind of ribbed bedform can develop subglacially through soft-bed deformation, where the ice flow undergoes lateral or longitudinal velocity gradients and the ice–bed interface is unlubricated; oblique ribbed bedforms develop beneath lateral shear margins, whereas transverse ribbed bedforms develop below frontal lobes. We infer that (i) ribbed bedforms strike orthogonally to the compressing axis of the horizontal strain ellipse of the ice surface and (ii) their development reveals distinctive types of subglacial drainage patterns: linked cavities below lateral shear margins and efficient meltwater channels below frontal lobes. These ribbed bedforms may act as convenient geomorphic markers to reconstruct lateral and frontal margins, constrain ice flow dynamics, and infer meltwater drainage characteristics of palaeo-ice streams. |
format |
Text |
author |
Vérité, Jean Ravier, Édouard Bourgeois, Olivier Pochat, Stéphane Lelandais, Thomas Mourgues, Régis Clark, Christopher D. Bessin, Paul Peigné, David Atkinson, Nigel |
spellingShingle |
Vérité, Jean Ravier, Édouard Bourgeois, Olivier Pochat, Stéphane Lelandais, Thomas Mourgues, Régis Clark, Christopher D. Bessin, Paul Peigné, David Atkinson, Nigel Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams |
author_facet |
Vérité, Jean Ravier, Édouard Bourgeois, Olivier Pochat, Stéphane Lelandais, Thomas Mourgues, Régis Clark, Christopher D. Bessin, Paul Peigné, David Atkinson, Nigel |
author_sort |
Vérité, Jean |
title |
Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams |
title_short |
Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams |
title_full |
Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams |
title_fullStr |
Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams |
title_full_unstemmed |
Formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams |
title_sort |
formation of ribbed bedforms below shear margins and lobes of palaeo-ice streams |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-2889-2021 https://tc.copernicus.org/articles/15/2889/2021/ |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-15-2889-2021 https://tc.copernicus.org/articles/15/2889/2021/ |
op_doi |
https://doi.org/10.5194/tc-15-2889-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
6 |
container_start_page |
2889 |
op_container_end_page |
2916 |
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1766031526501285888 |