The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel
The Northwest Atlantic Mid-Ocean Channel (NAMOC) is one of the largest deep-sea channels of the world's oceans. During the late Cenozoic glacial period, the channel played a major role in the depositional history of the Labrador Sea and northwest Atlantic in controlling sedimentation of a broad...
Published in: | Canadian Journal of Earth Sciences |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
1987
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1139/e87-155 http://www.nrcresearchpress.com/doi/pdf/10.1139/e87-155 |
id |
crcansciencepubl:10.1139/e87-155 |
---|---|
record_format |
openpolar |
spelling |
crcansciencepubl:10.1139/e87-155 2024-04-28T08:27:37+00:00 The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel Hesse, Reinhard Chough, Sung Kwun Rakofsky, Allan 1987 http://dx.doi.org/10.1139/e87-155 http://www.nrcresearchpress.com/doi/pdf/10.1139/e87-155 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 24, issue 8, page 1595-1624 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1987 crcansciencepubl https://doi.org/10.1139/e87-155 2024-04-09T06:56:31Z The Northwest Atlantic Mid-Ocean Channel (NAMOC) is one of the largest deep-sea channels of the world's oceans. During the late Cenozoic glacial period, the channel played a major role in the depositional history of the Labrador Sea and northwest Atlantic in controlling sedimentation of a broad (approx. 500 m thick and 200 km wide) lens of turbidites. This sediment sequence interfingers laterally with the acoustically transparent pelagic and contourite facies found in the Labrador Basin. The meandering channel is a depositional–erosional feature formed by submarine mass flows, predominantly turbidity currents.The channel contains a meandering talweg that appears to be associated with a sequence of submarine point bars containing thick-bedded, coarse-grained turbidites and gravel layers (channel-fill facies). Old channel positions on seismic profiles indicate that the channel has migrated laterally up to 30 km both to the west and to the east.Natural levees flank the channel for its entire length, extending laterally into turbidite plains 60–100 km wide. The spill-over facies comprises thin-bedded, fine-grained turbidites dominated by thinly laminated muds. Individual units of parallel-laminated mud, which result from single turbidity currents overtopping the channel banks, average 3 cm in thickness. A layer by layer correlation of a sequence of spill-over turbidites is possible between two adjacent cores 70 km apart. Coarse-grained off-channel sediments recently discovered on both levees at distances up to 55 km from the NAMOC occur in tributary channels.Turbidity current activity in the channel probably started with the onset of glaciation at about mid-Pliocene time and ceased at about 7000 years BP, when deglaciation proceeded rapidly. The sedimentation rate for the last episode of overbank deposition on the levees, which probably occurred between 11 000 and 7000 years BP, is 13 cm/1000 years. Towards the end of glacial episodes the northwestern Labrador Sea was probably covered with sea ice. Article in Journal/Newspaper Labrador Sea Northwest Atlantic Sea ice Canadian Science Publishing Canadian Journal of Earth Sciences 24 8 1595 1624 |
institution |
Open Polar |
collection |
Canadian Science Publishing |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Hesse, Reinhard Chough, Sung Kwun Rakofsky, Allan The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel |
topic_facet |
General Earth and Planetary Sciences |
description |
The Northwest Atlantic Mid-Ocean Channel (NAMOC) is one of the largest deep-sea channels of the world's oceans. During the late Cenozoic glacial period, the channel played a major role in the depositional history of the Labrador Sea and northwest Atlantic in controlling sedimentation of a broad (approx. 500 m thick and 200 km wide) lens of turbidites. This sediment sequence interfingers laterally with the acoustically transparent pelagic and contourite facies found in the Labrador Basin. The meandering channel is a depositional–erosional feature formed by submarine mass flows, predominantly turbidity currents.The channel contains a meandering talweg that appears to be associated with a sequence of submarine point bars containing thick-bedded, coarse-grained turbidites and gravel layers (channel-fill facies). Old channel positions on seismic profiles indicate that the channel has migrated laterally up to 30 km both to the west and to the east.Natural levees flank the channel for its entire length, extending laterally into turbidite plains 60–100 km wide. The spill-over facies comprises thin-bedded, fine-grained turbidites dominated by thinly laminated muds. Individual units of parallel-laminated mud, which result from single turbidity currents overtopping the channel banks, average 3 cm in thickness. A layer by layer correlation of a sequence of spill-over turbidites is possible between two adjacent cores 70 km apart. Coarse-grained off-channel sediments recently discovered on both levees at distances up to 55 km from the NAMOC occur in tributary channels.Turbidity current activity in the channel probably started with the onset of glaciation at about mid-Pliocene time and ceased at about 7000 years BP, when deglaciation proceeded rapidly. The sedimentation rate for the last episode of overbank deposition on the levees, which probably occurred between 11 000 and 7000 years BP, is 13 cm/1000 years. Towards the end of glacial episodes the northwestern Labrador Sea was probably covered with sea ice. |
format |
Article in Journal/Newspaper |
author |
Hesse, Reinhard Chough, Sung Kwun Rakofsky, Allan |
author_facet |
Hesse, Reinhard Chough, Sung Kwun Rakofsky, Allan |
author_sort |
Hesse, Reinhard |
title |
The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel |
title_short |
The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel |
title_full |
The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel |
title_fullStr |
The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel |
title_full_unstemmed |
The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea. V. Sedimentology of a giant deep-sea channel |
title_sort |
northwest atlantic mid-ocean channel of the labrador sea. v. sedimentology of a giant deep-sea channel |
publisher |
Canadian Science Publishing |
publishDate |
1987 |
url |
http://dx.doi.org/10.1139/e87-155 http://www.nrcresearchpress.com/doi/pdf/10.1139/e87-155 |
genre |
Labrador Sea Northwest Atlantic Sea ice |
genre_facet |
Labrador Sea Northwest Atlantic Sea ice |
op_source |
Canadian Journal of Earth Sciences volume 24, issue 8, page 1595-1624 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e87-155 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
24 |
container_issue |
8 |
container_start_page |
1595 |
op_container_end_page |
1624 |
_version_ |
1797586478958641152 |