Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ?
Elucidating the controls on the location and vigor of ice streams is crucial to understanding the processes that lead to fast disintegration of ice flows and ice sheets. In the former North American Laurentide ice sheet, ice stream occurrence appears to have been governed by topographic troughs or a...
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ftunivdurham:oai:dro.dur.ac.uk.OAI2:4432 2023-05-15T16:40:16+02:00 Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ? Stokes, C.R. Clark, C.D. 2003-04-01 http://dro.dur.ac.uk/4432/ https://doi.org/10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 unknown Geological Society of America dro:4432 issn:0091-7613 issn: 1943-2682 doi:10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 http://dro.dur.ac.uk/4432/ http://dx.doi.org/10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 Geological Society of America, P.O. Box 9140, Boulder, CO 80301-9140 USA (http://www.geosociety.org) Geology, 2003, Vol.31(4), pp.347-350 [Peer Reviewed Journal] Ice stream Laurentide ice sheet Canadian Shield Article PeerReviewed 2003 ftunivdurham https://doi.org/10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 2020-05-28T22:26:46Z Elucidating the controls on the location and vigor of ice streams is crucial to understanding the processes that lead to fast disintegration of ice flows and ice sheets. In the former North American Laurentide ice sheet, ice stream occurrence appears to have been governed by topographic troughs or areas of soft-sediment geology. This paper reports robust evidence of a major paleo–ice stream over the northwestern Canadian Shield, an area previously assumed to be incompatible with fast ice flow because of the low relief and relatively hard bedrock. A coherent pattern of subglacial bedforms (drumlins and megascale glacial lineations) demarcates the ice stream flow set, which exhibits a convergent onset zone, a narrow main trunk with abrupt lateral margins, and a lobate terminus. Variations in bedform elongation ratio within the flow set match theoretical expectations of ice velocity. In the center of the ice stream, extremely parallel megascale glacial lineations tens of kilometers long with elongation ratios in excess of 40:1 attest to a single episode of rapid ice flow. We conclude that while bed properties are likely to be influential in determining the occurrence and vigor of ice streams, contrary to established views, widespread soft-bed geology is not an essential requirement for those ice streams without topographic control. We speculate that the ice stream acted as a release valve on ice-sheet mass balance and was initiated by the presence of a proglacial lake that destabilized the ice-sheet margin and propagated fast ice flow through a series of thermomechanical feedbacks involving ice flow and temperature. Article in Journal/Newspaper Ice Sheet Durham University: Durham Research Online |
institution |
Open Polar |
collection |
Durham University: Durham Research Online |
op_collection_id |
ftunivdurham |
language |
unknown |
topic |
Ice stream Laurentide ice sheet Canadian Shield |
spellingShingle |
Ice stream Laurentide ice sheet Canadian Shield Stokes, C.R. Clark, C.D. Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ? |
topic_facet |
Ice stream Laurentide ice sheet Canadian Shield |
description |
Elucidating the controls on the location and vigor of ice streams is crucial to understanding the processes that lead to fast disintegration of ice flows and ice sheets. In the former North American Laurentide ice sheet, ice stream occurrence appears to have been governed by topographic troughs or areas of soft-sediment geology. This paper reports robust evidence of a major paleo–ice stream over the northwestern Canadian Shield, an area previously assumed to be incompatible with fast ice flow because of the low relief and relatively hard bedrock. A coherent pattern of subglacial bedforms (drumlins and megascale glacial lineations) demarcates the ice stream flow set, which exhibits a convergent onset zone, a narrow main trunk with abrupt lateral margins, and a lobate terminus. Variations in bedform elongation ratio within the flow set match theoretical expectations of ice velocity. In the center of the ice stream, extremely parallel megascale glacial lineations tens of kilometers long with elongation ratios in excess of 40:1 attest to a single episode of rapid ice flow. We conclude that while bed properties are likely to be influential in determining the occurrence and vigor of ice streams, contrary to established views, widespread soft-bed geology is not an essential requirement for those ice streams without topographic control. We speculate that the ice stream acted as a release valve on ice-sheet mass balance and was initiated by the presence of a proglacial lake that destabilized the ice-sheet margin and propagated fast ice flow through a series of thermomechanical feedbacks involving ice flow and temperature. |
format |
Article in Journal/Newspaper |
author |
Stokes, C.R. Clark, C.D. |
author_facet |
Stokes, C.R. Clark, C.D. |
author_sort |
Stokes, C.R. |
title |
Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ? |
title_short |
Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ? |
title_full |
Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ? |
title_fullStr |
Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ? |
title_full_unstemmed |
Laurentide ice streaming on the Canadian Shield : a conflict with the soft-bedded ice stream paradigm ? |
title_sort |
laurentide ice streaming on the canadian shield : a conflict with the soft-bedded ice stream paradigm ? |
publisher |
Geological Society of America |
publishDate |
2003 |
url |
http://dro.dur.ac.uk/4432/ https://doi.org/10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Geology, 2003, Vol.31(4), pp.347-350 [Peer Reviewed Journal] |
op_relation |
dro:4432 issn:0091-7613 issn: 1943-2682 doi:10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 http://dro.dur.ac.uk/4432/ http://dx.doi.org/10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 |
op_rights |
Geological Society of America, P.O. Box 9140, Boulder, CO 80301-9140 USA (http://www.geosociety.org) |
op_doi |
https://doi.org/10.1130/0091-7613(2003)031<0347:LISOTC>2.0.CO;2 |
_version_ |
1766030648303157248 |