Instabilities in the Labrador Sea water mass structure during the last climatic cycle
In the modern Labrador Sea, the North Atlantic deep water components are found below the ~2 km deep, intermediate Labrador Sea water (LSW) mass, which is renewed locally through winter convective mixing. This water mass structure remained relatively stable since ~9.5 14 C ka BP, as indicated by isot...
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crcansciencepubl:10.1139/e99-108 2024-06-23T07:54:26+00:00 Instabilities in the Labrador Sea water mass structure during the last climatic cycle Hillaire-Marcel, Claude Bilodeau, Guy 2000 http://dx.doi.org/10.1139/e99-108 http://www.nrcresearchpress.com/doi/pdf/10.1139/e99-108 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 37, issue 5, page 795-809 ISSN 0008-4077 1480-3313 journal-article 2000 crcansciencepubl https://doi.org/10.1139/e99-108 2024-05-30T08:13:48Z In the modern Labrador Sea, the North Atlantic deep water components are found below the ~2 km deep, intermediate Labrador Sea water (LSW) mass, which is renewed locally through winter convective mixing. This water mass structure remained relatively stable since ~9.5 14 C ka BP, as indicated by isotopic studies of foraminifer assemblages from deep-sea cores. Almost constant differences in δ 18 O values are observed between major species. These average -0.5 between the epipelagic species Globigerina bulloides and the mesopelagic species Neogloboquadrina pachyderma, left coiled, and -1 between Neogloboquadrina pachyderma and the benthic species Cibicides wuellerstorfi, after correction for Cibicides wuellerstorfi specific fractionation. These isotopic compositions represent thermohaline conditions in surface waters, in the pycnocline with the LSW, and in the deep component of the North Atlantic deep water, respectively. A drastically different structure characterized the glacial Labrador Sea. Differences in δ 18 O values of ~ -2 to -2.5 are then observed between Globigerina bulloides and benthic species, indicative of a strong halocline between the corresponding water masses, thus for reduced production of intermediate waters. During the same interval, Neogloboquadrina pachyderma shows 13 C and 18 O fluctuations of 1 to 1.5 amplitude, in phase with Heinrich-Bond events and higher frequency climate oscillations. The δ 18 O values in Neogloboquadrina pachyderma vary between those of Globigerina bulloides and of benthic foraminifers, suggesting large amplitude bathymetric fluctuations of the halo-thermocline above and below the bathymetric range occupied by Neogloboquadrina pachyderma. Minimum δ 18 O values in Neogloboquadrina pachyderma match intervals of maximum ice rafting deposition, such as the late Heinrich events, thus intervals with a deeper, more dilute buoyant surface water layer. Article in Journal/Newspaper Labrador Sea Neogloboquadrina pachyderma North Atlantic Deep Water North Atlantic Canadian Science Publishing Canadian Journal of Earth Sciences 37 5 795 809 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
In the modern Labrador Sea, the North Atlantic deep water components are found below the ~2 km deep, intermediate Labrador Sea water (LSW) mass, which is renewed locally through winter convective mixing. This water mass structure remained relatively stable since ~9.5 14 C ka BP, as indicated by isotopic studies of foraminifer assemblages from deep-sea cores. Almost constant differences in δ 18 O values are observed between major species. These average -0.5 between the epipelagic species Globigerina bulloides and the mesopelagic species Neogloboquadrina pachyderma, left coiled, and -1 between Neogloboquadrina pachyderma and the benthic species Cibicides wuellerstorfi, after correction for Cibicides wuellerstorfi specific fractionation. These isotopic compositions represent thermohaline conditions in surface waters, in the pycnocline with the LSW, and in the deep component of the North Atlantic deep water, respectively. A drastically different structure characterized the glacial Labrador Sea. Differences in δ 18 O values of ~ -2 to -2.5 are then observed between Globigerina bulloides and benthic species, indicative of a strong halocline between the corresponding water masses, thus for reduced production of intermediate waters. During the same interval, Neogloboquadrina pachyderma shows 13 C and 18 O fluctuations of 1 to 1.5 amplitude, in phase with Heinrich-Bond events and higher frequency climate oscillations. The δ 18 O values in Neogloboquadrina pachyderma vary between those of Globigerina bulloides and of benthic foraminifers, suggesting large amplitude bathymetric fluctuations of the halo-thermocline above and below the bathymetric range occupied by Neogloboquadrina pachyderma. Minimum δ 18 O values in Neogloboquadrina pachyderma match intervals of maximum ice rafting deposition, such as the late Heinrich events, thus intervals with a deeper, more dilute buoyant surface water layer. |
format |
Article in Journal/Newspaper |
author |
Hillaire-Marcel, Claude Bilodeau, Guy |
spellingShingle |
Hillaire-Marcel, Claude Bilodeau, Guy Instabilities in the Labrador Sea water mass structure during the last climatic cycle |
author_facet |
Hillaire-Marcel, Claude Bilodeau, Guy |
author_sort |
Hillaire-Marcel, Claude |
title |
Instabilities in the Labrador Sea water mass structure during the last climatic cycle |
title_short |
Instabilities in the Labrador Sea water mass structure during the last climatic cycle |
title_full |
Instabilities in the Labrador Sea water mass structure during the last climatic cycle |
title_fullStr |
Instabilities in the Labrador Sea water mass structure during the last climatic cycle |
title_full_unstemmed |
Instabilities in the Labrador Sea water mass structure during the last climatic cycle |
title_sort |
instabilities in the labrador sea water mass structure during the last climatic cycle |
publisher |
Canadian Science Publishing |
publishDate |
2000 |
url |
http://dx.doi.org/10.1139/e99-108 http://www.nrcresearchpress.com/doi/pdf/10.1139/e99-108 |
genre |
Labrador Sea Neogloboquadrina pachyderma North Atlantic Deep Water North Atlantic |
genre_facet |
Labrador Sea Neogloboquadrina pachyderma North Atlantic Deep Water North Atlantic |
op_source |
Canadian Journal of Earth Sciences volume 37, issue 5, page 795-809 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e99-108 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
37 |
container_issue |
5 |
container_start_page |
795 |
op_container_end_page |
809 |
_version_ |
1802646583628529664 |