Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum
Abstract This paper investigates the processes governing bedrock bedform evolution in ice sheet and ice stream areas in central West Greenland, and explores the evidence for a cross‐shelf ice stream at the Last Glacial Maximum (LGM). To the east of Sisimiut the formation of streamlined bedforms with...
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crwiley:10.1002/jqs.1354 2024-06-02T08:07:30+00:00 Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum Roberts, David H. Long, Antony J. Davies, Bethan J. Simpson, Matthew J. R. Schnabel, Christoph Durham University NERC CIAF 2010 http://dx.doi.org/10.1002/jqs.1354 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1354 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1354 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Quaternary Science volume 25, issue 6, page 850-864 ISSN 0267-8179 1099-1417 journal-article 2010 crwiley https://doi.org/10.1002/jqs.1354 2024-05-03T11:42:42Z Abstract This paper investigates the processes governing bedrock bedform evolution in ice sheet and ice stream areas in central West Greenland, and explores the evidence for a cross‐shelf ice stream at the Last Glacial Maximum (LGM). To the east of Sisimiut the formation of streamlined bedforms with high elongation ratios and high bedform density has been controlled by geological structure and topography in slow‐flowing ice sheet areas. At the coast, the effects of regional flow convergence, caused by coastal fjord orientation, routed ice into the Sisimiut/Itilleq area where it formed an ice stream onset zone. This funnelled ice into an offshore trough (Holsteinsborg Dyb), resulting in a southwesterly regional ice flow direction and the formation of a topographically routed ice stream (Holsteinsborg Isbrae). To the south of this, striae and bedform evidence show that local valley glaciers initially flowed east to west across the coast, but were later redirected by the Itilleq Fjord ice which turned southwestward due to diffluent flow and deflection by Holsteinsborg Isbrae. Roches moutonnées in this area have low elongation ratios and high bedform density, but do not provide unequivocal support for ice streaming, as they are a product of both bedrock structure and changes in ice flow direction, rather than enhanced flow velocities. Cosmogenic surface exposure ages limit maximum ice sheet surface elevation to ca. 755–810 m above sea level in this region. Such ice thickness enabled Holsteinsborg Isbrae to reach the mid/outer continental shelf during the LGM, and to contribute to the formation of a trough mouth fan and the Outer Hellefisk moraines. Initial deglaciation across this region was driven by rising sea level and increasing air temperatures prior to the Bølling Interstadial at ca. 14.5 cal. ka BP. Between 12 and 10 cal. ka BP both increased air and ocean temperatures post the Younger Dryas, and peak sea‐level rise up to the marine limit, caused accelerated thinning and marginal retreat through calving, ... Article in Journal/Newspaper Greenland Ice Sheet Itilleq Sisimiut Wiley Online Library Greenland Sisimiut ENVELOPE(-53.674,-53.674,66.939,66.939) Journal of Quaternary Science 25 6 850 864 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract This paper investigates the processes governing bedrock bedform evolution in ice sheet and ice stream areas in central West Greenland, and explores the evidence for a cross‐shelf ice stream at the Last Glacial Maximum (LGM). To the east of Sisimiut the formation of streamlined bedforms with high elongation ratios and high bedform density has been controlled by geological structure and topography in slow‐flowing ice sheet areas. At the coast, the effects of regional flow convergence, caused by coastal fjord orientation, routed ice into the Sisimiut/Itilleq area where it formed an ice stream onset zone. This funnelled ice into an offshore trough (Holsteinsborg Dyb), resulting in a southwesterly regional ice flow direction and the formation of a topographically routed ice stream (Holsteinsborg Isbrae). To the south of this, striae and bedform evidence show that local valley glaciers initially flowed east to west across the coast, but were later redirected by the Itilleq Fjord ice which turned southwestward due to diffluent flow and deflection by Holsteinsborg Isbrae. Roches moutonnées in this area have low elongation ratios and high bedform density, but do not provide unequivocal support for ice streaming, as they are a product of both bedrock structure and changes in ice flow direction, rather than enhanced flow velocities. Cosmogenic surface exposure ages limit maximum ice sheet surface elevation to ca. 755–810 m above sea level in this region. Such ice thickness enabled Holsteinsborg Isbrae to reach the mid/outer continental shelf during the LGM, and to contribute to the formation of a trough mouth fan and the Outer Hellefisk moraines. Initial deglaciation across this region was driven by rising sea level and increasing air temperatures prior to the Bølling Interstadial at ca. 14.5 cal. ka BP. Between 12 and 10 cal. ka BP both increased air and ocean temperatures post the Younger Dryas, and peak sea‐level rise up to the marine limit, caused accelerated thinning and marginal retreat through calving, ... |
author2 |
Durham University NERC CIAF |
format |
Article in Journal/Newspaper |
author |
Roberts, David H. Long, Antony J. Davies, Bethan J. Simpson, Matthew J. R. Schnabel, Christoph |
spellingShingle |
Roberts, David H. Long, Antony J. Davies, Bethan J. Simpson, Matthew J. R. Schnabel, Christoph Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum |
author_facet |
Roberts, David H. Long, Antony J. Davies, Bethan J. Simpson, Matthew J. R. Schnabel, Christoph |
author_sort |
Roberts, David H. |
title |
Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum |
title_short |
Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum |
title_full |
Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum |
title_fullStr |
Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum |
title_full_unstemmed |
Ice stream influence on West Greenland Ice Sheet dynamics during the Last Glacial Maximum |
title_sort |
ice stream influence on west greenland ice sheet dynamics during the last glacial maximum |
publisher |
Wiley |
publishDate |
2010 |
url |
http://dx.doi.org/10.1002/jqs.1354 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1354 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1354 |
long_lat |
ENVELOPE(-53.674,-53.674,66.939,66.939) |
geographic |
Greenland Sisimiut |
geographic_facet |
Greenland Sisimiut |
genre |
Greenland Ice Sheet Itilleq Sisimiut |
genre_facet |
Greenland Ice Sheet Itilleq Sisimiut |
op_source |
Journal of Quaternary Science volume 25, issue 6, page 850-864 ISSN 0267-8179 1099-1417 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/jqs.1354 |
container_title |
Journal of Quaternary Science |
container_volume |
25 |
container_issue |
6 |
container_start_page |
850 |
op_container_end_page |
864 |
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1800752587458215936 |