The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet
Side-scan sonar imagery, 40 in$ sp3$ sleeve gun and 3.5 kHz high-resolution profiles reveal a dichotomy of the upper Labrador Slope into (i) a low-relief sector off Hudson Strait that is dominated by mass-transport deposits resulting from the direct input of subglacially derived debris, and (ii) a h...
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McGill University
1995
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ftcanadathes:oai:collectionscanada.gc.ca:QMM.29064 2023-05-15T16:35:39+02:00 The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet Klaucke, Ingo Hesse, Reinhard (advisor) Doctor of Philosophy (Department of Earth and Planetary Sciences.) 1995 application/pdf http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29064 en eng McGill University alephsysno: 001472745 proquestno: NN08122 Theses scanned by UMI/ProQuest. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29064 All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. Physical Geography Geology Physical Oceanography Electronic Thesis or Dissertation 1995 ftcanadathes 2014-02-16T00:47:26Z Side-scan sonar imagery, 40 in$ sp3$ sleeve gun and 3.5 kHz high-resolution profiles reveal a dichotomy of the upper Labrador Slope into (i) a low-relief sector off Hudson Strait that is dominated by mass-transport deposits resulting from the direct input of subglacially derived debris, and (ii) a high-relief sector to the south resulting mainly from deposition out of turbid surface plumes, and headward canyon erosion. This dichotomy continues in the Labrador Basin, where the leveed Northwest Atlantic Mid-Ocean Channel (NAMOC) is flanked by a sandy submarine braidplain in the east, which is the basinward extension of the differences on the upper slope. The floodplain west of NAMOC contains extensive debris-flow deposits generated on the Labrador Slope. The meandering low-sinuosity, low-gradient NAMOC contains three segments: In the upper equilibrium channel, channel morphology is in equilibrium with spill-over from low-velocity, low-density upper portions of turbidity currents flowing in the channel; in the middle modified equilibrium channel, equilibrium morphology is altered by the confluence with tributary channels, and in the lower segment, channel morphology and position is controlled by basement topography (oceanic fracture zones and seamounts). The NAMOC levees interfinger with the braidplain deposits to the east and prograde southeastward in 7-8 packages. Most packages show a strong cross-channel decrease in thickness, and a strong asymmetry between the left and the right levee, as a Coriolis effect. The braidplain east of the NAMOC, which developed simultaneously with and prior to the NAMOC, shows a north to south gradient from laterally very extensive to highly channelized deposits. In the channelized part, channel positions change rapidly and deposits vary from sandy to gravelly. Extensive sheet-like turbidity currents on the braidplain may have been caused by catastrophic outbursts of subglacial lakes during times of ice-stream surges. Quantitative morphological analysis shows that the NAMOC is characterized by particularly low sinuosities due to very low channel-gradients compared to other submarine channels. The channel displays several features not recognized before in the deep-sea, or not in the same detail; including submarine hanging valleys and chute pools, submarine point-bars within the channel, coarse-grained wash-over fans on the lee-side of the levees, and terraces within the channel. The talweg is variable in depth and meanders within the channel. An up to 80 m deep talweg is present in the distal NAMOC resulting from flow restrictions due to seamounts. Channel morphology as well as grain size of spill-over deposits suggest that the flow tops of turbidity currents in the NAMOC are slow ($<$0.7 m/s) and dilute ($<$12 kg/m$ sp3$). Gravel deposits in the channel require velocities of 6.5-8 m/s for suspension transport, suggesting a strong vertical velocity and density gradient. Thesis Hudson Strait Labrador Sea Northwest Atlantic Theses Canada/Thèses Canada (Library and Archives Canada) Hudson Hudson Strait ENVELOPE(-70.000,-70.000,62.000,62.000) Northwest Atlantic Mid-Ocean Channel ENVELOPE(-52.709,-52.709,58.577,58.577) |
institution |
Open Polar |
collection |
Theses Canada/Thèses Canada (Library and Archives Canada) |
op_collection_id |
ftcanadathes |
language |
English |
topic |
Physical Geography Geology Physical Oceanography |
spellingShingle |
Physical Geography Geology Physical Oceanography Klaucke, Ingo The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet |
topic_facet |
Physical Geography Geology Physical Oceanography |
description |
Side-scan sonar imagery, 40 in$ sp3$ sleeve gun and 3.5 kHz high-resolution profiles reveal a dichotomy of the upper Labrador Slope into (i) a low-relief sector off Hudson Strait that is dominated by mass-transport deposits resulting from the direct input of subglacially derived debris, and (ii) a high-relief sector to the south resulting mainly from deposition out of turbid surface plumes, and headward canyon erosion. This dichotomy continues in the Labrador Basin, where the leveed Northwest Atlantic Mid-Ocean Channel (NAMOC) is flanked by a sandy submarine braidplain in the east, which is the basinward extension of the differences on the upper slope. The floodplain west of NAMOC contains extensive debris-flow deposits generated on the Labrador Slope. The meandering low-sinuosity, low-gradient NAMOC contains three segments: In the upper equilibrium channel, channel morphology is in equilibrium with spill-over from low-velocity, low-density upper portions of turbidity currents flowing in the channel; in the middle modified equilibrium channel, equilibrium morphology is altered by the confluence with tributary channels, and in the lower segment, channel morphology and position is controlled by basement topography (oceanic fracture zones and seamounts). The NAMOC levees interfinger with the braidplain deposits to the east and prograde southeastward in 7-8 packages. Most packages show a strong cross-channel decrease in thickness, and a strong asymmetry between the left and the right levee, as a Coriolis effect. The braidplain east of the NAMOC, which developed simultaneously with and prior to the NAMOC, shows a north to south gradient from laterally very extensive to highly channelized deposits. In the channelized part, channel positions change rapidly and deposits vary from sandy to gravelly. Extensive sheet-like turbidity currents on the braidplain may have been caused by catastrophic outbursts of subglacial lakes during times of ice-stream surges. Quantitative morphological analysis shows that the NAMOC is characterized by particularly low sinuosities due to very low channel-gradients compared to other submarine channels. The channel displays several features not recognized before in the deep-sea, or not in the same detail; including submarine hanging valleys and chute pools, submarine point-bars within the channel, coarse-grained wash-over fans on the lee-side of the levees, and terraces within the channel. The talweg is variable in depth and meanders within the channel. An up to 80 m deep talweg is present in the distal NAMOC resulting from flow restrictions due to seamounts. Channel morphology as well as grain size of spill-over deposits suggest that the flow tops of turbidity currents in the NAMOC are slow ($<$0.7 m/s) and dilute ($<$12 kg/m$ sp3$). Gravel deposits in the channel require velocities of 6.5-8 m/s for suspension transport, suggesting a strong vertical velocity and density gradient. |
author2 |
Hesse, Reinhard (advisor) |
format |
Thesis |
author |
Klaucke, Ingo |
author_facet |
Klaucke, Ingo |
author_sort |
Klaucke, Ingo |
title |
The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet |
title_short |
The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet |
title_full |
The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet |
title_fullStr |
The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet |
title_full_unstemmed |
The submarine drainage system of the Labrador Sea : result of glacial input from the Laurentide icesheet |
title_sort |
submarine drainage system of the labrador sea : result of glacial input from the laurentide icesheet |
publisher |
McGill University |
publishDate |
1995 |
url |
http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29064 |
op_coverage |
Doctor of Philosophy (Department of Earth and Planetary Sciences.) |
long_lat |
ENVELOPE(-70.000,-70.000,62.000,62.000) ENVELOPE(-52.709,-52.709,58.577,58.577) |
geographic |
Hudson Hudson Strait Northwest Atlantic Mid-Ocean Channel |
geographic_facet |
Hudson Hudson Strait Northwest Atlantic Mid-Ocean Channel |
genre |
Hudson Strait Labrador Sea Northwest Atlantic |
genre_facet |
Hudson Strait Labrador Sea Northwest Atlantic |
op_relation |
alephsysno: 001472745 proquestno: NN08122 Theses scanned by UMI/ProQuest. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29064 |
op_rights |
All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
_version_ |
1766025930599301120 |