Geological evidence for past subglacial conditions: dry-based vs wet-based ice
Amongst the geological community there is now consensus that the West Antarctic ice sheet reached outer continental shelf positions in most sectors during its last maximum extent. This conclusion is mainly formed on the basis of extensive palaeo-glaciological work that has been conducted during the...
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ftawi:oai:epic.awi.de:38970 2023-05-15T13:24:17+02:00 Geological evidence for past subglacial conditions: dry-based vs wet-based ice Klages, Johann Philipp Kuhn, Gerhard Graham, Alastair G. C. Smith, James A. Hillenbrand, Claus-Dieter 2015 https://epic.awi.de/id/eprint/38970/ https://hdl.handle.net/10013/epic.46227 unknown International Glaciological Society Klages, J. P. orcid:0000-0003-0968-1183 , Kuhn, G. orcid:0000-0001-6069-7485 , Graham, A. G. C. , Smith, J. A. and Hillenbrand, C. D. (2015) Geological evidence for past subglacial conditions: dry-based vs wet-based ice , International Symposium on Hydrology of Glaciers and Ice Sheets, Höfn, Island, 21 June 2015 - 27 June 2015 . hdl:10013/epic.46227 EPIC3International Symposium on Hydrology of Glaciers and Ice Sheets, Höfn, Island, 2015-06-21-2015-06-27London, International Glaciological Society Conference notRev 2015 ftawi 2021-12-24T15:40:48Z Amongst the geological community there is now consensus that the West Antarctic ice sheet reached outer continental shelf positions in most sectors during its last maximum extent. This conclusion is mainly formed on the basis of extensive palaeo-glaciological work that has been conducted during the past decade in various drainage sectors of the ice sheet. In these regions of the continental shelf, reconstructions of ice-sheet extent, relative flow velocities and retreat have mainly focused on deeper cross-shelf depressions, generally interpreted as pathways of fast-flowing palaeo-ice streams. Within these troughs, the prevalent glacial landforms consist of continuums of streamlined bedforms (e.g. mega-scale glacial lineations and drumlins) whose progressive increase in elongation is indicative of formation beneath wet-based streaming ice. However, extensive shelf areas surrounding these spatially restricted deeper corridors largely lack well-preserved glacial landforms, thereby inhibiting reliable shelf-wide ice-flow reconstructions. Recently, by analysing new high-resolution bathymetric data from these inter-ice stream ridges, former basal ice conditions could be illuminated for the first time. Subglacial landforms such as hill-hole pairs, sediment rafts and crevasse-squeeze ridges clearly indicate cold/dry-based, slow-flowing or even stagnant ice on the shelf areas outside the troughs. Here we present a new compilation of bathymetric datasets from the eastern Amundsen Sea Embayment covering both palaeo-ice stream troughs and adjacent inter-ice stream ridges. It allows a clear distinction between different basal ice regimes (dry-based vs wet-based) across the former ice-sheet bed. However, we additionally identified regions of apparent changes in basal conditions, i.e. regions where hill-hole pairs overprint mega-scale glacial lineations, thereby suggesting cold/dry-based basal conditions prior to final retreat rather than streaming flow. Generally, the ability to reconstruct the width and basal form of the West Antarctic ice sheet in this manner, across other parts of the Antarctic shelf, will greatly aid numerical ice-sheet models that aim to simulate past configurations of the ice sheet and its evolution to the present day. Conference Object Amundsen Sea Antarc* Antarctic Ice Sheet Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Antarctic The Antarctic Amundsen Sea West Antarctic Ice Sheet |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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ftawi |
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description |
Amongst the geological community there is now consensus that the West Antarctic ice sheet reached outer continental shelf positions in most sectors during its last maximum extent. This conclusion is mainly formed on the basis of extensive palaeo-glaciological work that has been conducted during the past decade in various drainage sectors of the ice sheet. In these regions of the continental shelf, reconstructions of ice-sheet extent, relative flow velocities and retreat have mainly focused on deeper cross-shelf depressions, generally interpreted as pathways of fast-flowing palaeo-ice streams. Within these troughs, the prevalent glacial landforms consist of continuums of streamlined bedforms (e.g. mega-scale glacial lineations and drumlins) whose progressive increase in elongation is indicative of formation beneath wet-based streaming ice. However, extensive shelf areas surrounding these spatially restricted deeper corridors largely lack well-preserved glacial landforms, thereby inhibiting reliable shelf-wide ice-flow reconstructions. Recently, by analysing new high-resolution bathymetric data from these inter-ice stream ridges, former basal ice conditions could be illuminated for the first time. Subglacial landforms such as hill-hole pairs, sediment rafts and crevasse-squeeze ridges clearly indicate cold/dry-based, slow-flowing or even stagnant ice on the shelf areas outside the troughs. Here we present a new compilation of bathymetric datasets from the eastern Amundsen Sea Embayment covering both palaeo-ice stream troughs and adjacent inter-ice stream ridges. It allows a clear distinction between different basal ice regimes (dry-based vs wet-based) across the former ice-sheet bed. However, we additionally identified regions of apparent changes in basal conditions, i.e. regions where hill-hole pairs overprint mega-scale glacial lineations, thereby suggesting cold/dry-based basal conditions prior to final retreat rather than streaming flow. Generally, the ability to reconstruct the width and basal form of the West Antarctic ice sheet in this manner, across other parts of the Antarctic shelf, will greatly aid numerical ice-sheet models that aim to simulate past configurations of the ice sheet and its evolution to the present day. |
format |
Conference Object |
author |
Klages, Johann Philipp Kuhn, Gerhard Graham, Alastair G. C. Smith, James A. Hillenbrand, Claus-Dieter |
spellingShingle |
Klages, Johann Philipp Kuhn, Gerhard Graham, Alastair G. C. Smith, James A. Hillenbrand, Claus-Dieter Geological evidence for past subglacial conditions: dry-based vs wet-based ice |
author_facet |
Klages, Johann Philipp Kuhn, Gerhard Graham, Alastair G. C. Smith, James A. Hillenbrand, Claus-Dieter |
author_sort |
Klages, Johann Philipp |
title |
Geological evidence for past subglacial conditions: dry-based vs wet-based ice |
title_short |
Geological evidence for past subglacial conditions: dry-based vs wet-based ice |
title_full |
Geological evidence for past subglacial conditions: dry-based vs wet-based ice |
title_fullStr |
Geological evidence for past subglacial conditions: dry-based vs wet-based ice |
title_full_unstemmed |
Geological evidence for past subglacial conditions: dry-based vs wet-based ice |
title_sort |
geological evidence for past subglacial conditions: dry-based vs wet-based ice |
publisher |
International Glaciological Society |
publishDate |
2015 |
url |
https://epic.awi.de/id/eprint/38970/ https://hdl.handle.net/10013/epic.46227 |
geographic |
Antarctic The Antarctic Amundsen Sea West Antarctic Ice Sheet |
geographic_facet |
Antarctic The Antarctic Amundsen Sea West Antarctic Ice Sheet |
genre |
Amundsen Sea Antarc* Antarctic Ice Sheet |
genre_facet |
Amundsen Sea Antarc* Antarctic Ice Sheet |
op_source |
EPIC3International Symposium on Hydrology of Glaciers and Ice Sheets, Höfn, Island, 2015-06-21-2015-06-27London, International Glaciological Society |
op_relation |
Klages, J. P. orcid:0000-0003-0968-1183 , Kuhn, G. orcid:0000-0001-6069-7485 , Graham, A. G. C. , Smith, J. A. and Hillenbrand, C. D. (2015) Geological evidence for past subglacial conditions: dry-based vs wet-based ice , International Symposium on Hydrology of Glaciers and Ice Sheets, Höfn, Island, 21 June 2015 - 27 June 2015 . hdl:10013/epic.46227 |
_version_ |
1766378559993020416 |