Labrador Sea bottom water provenance and REE exchange during the past 35,000 years

Deep waters of the Labrador Sea (LS) are important contributors to the Atlantic Meridional Overturning Circulation, but their water mass structure has been highly variable and sensitive to climatic changes on different time scales. The LS is also an area of intense exchange of rare earth elements (R...

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Main Authors: Blaser, Patrick, Gutjahr, Marcus, Pöppelmeier, Frerk, Frank, Martin, Kaboth-Bahr, Stefanie, Lippold, Jörg
Format: Text
Language:unknown
Published: Elsevier 2020
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Online Access:https://dx.doi.org/10.48350/158655
https://boris.unibe.ch/158655/
id ftdatacite:10.48350/158655
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spelling ftdatacite:10.48350/158655 2023-05-15T16:35:32+02:00 Labrador Sea bottom water provenance and REE exchange during the past 35,000 years Blaser, Patrick Gutjahr, Marcus Pöppelmeier, Frerk Frank, Martin Kaboth-Bahr, Stefanie Lippold, Jörg 2020 https://dx.doi.org/10.48350/158655 https://boris.unibe.ch/158655/ unknown Elsevier restricted access publisher holds copyright http://purl.org/coar/access_right/c_16ec 530 Physics Text article-journal journal article ScholarlyArticle 2020 ftdatacite https://doi.org/10.48350/158655 2021-11-05T12:55:41Z Deep waters of the Labrador Sea (LS) are important contributors to the Atlantic Meridional Overturning Circulation, but their water mass structure has been highly variable and sensitive to climatic changes on different time scales. The LS is also an area of intense exchange of rare earth elements (REE) between seawater and the underlying sediments, which complicates the reconstruction of past deep water provenance based on radiogenic neodymium (Nd) isotopes. Most notably, Northwest Atlantic Bottom Water exchanges Nd with Archaean age Laurentian detritus, resulting in a significant shift to less radiogenic Nd isotope signatures before it enters the North Atlantic to form the deep part of North Atlantic Deep Water. Here we show that the authigenic fractions of LS core top sediments carry Nd isotope signatures intermediate between bottom water and detritus and thus reflect pore waters that incorporate a mixture of both signatures. We furthermore find that detrital imprints on pore waters led to shifts of REE patterns in the authigenic fraction towards detrital signatures in the past during times of enhanced supply of glacially eroded material from Hudson Bay to the LS, as recorded by radiogenic lead isotopes. This allows an estimation of the intensity of past benthic REE exchange inside the LS. We exploit variations in the mid REE enrichment in the authigenic phase to propose a correction to one LS Nd isotope record for detrital imprints originating from pore water exchange. The corrected ϵNd signatures are argued to more accurately reflect those of past bottom waters. This correction results in past LS bottom water signatures of −16 ± 1 during MIS 2 and 3, considerably less radiogenic than today. This implies that no southern sourced waters advanced into the LS during the last 35 ka and instead supports continuous bottom water sourcing from the Nordic Seas. It thus seems likely that LS bottom waters supplied unradiogenic Nd to abyssal Glacial North Atlantic Bottom Water in the Northwest Atlantic, as was previously hypothesized. Text Hudson Bay Labrador Sea Nordic Seas North Atlantic Deep Water North Atlantic Northwest Atlantic DataCite Metadata Store (German National Library of Science and Technology) Hudson Hudson Bay
institution Open Polar
collection DataCite Metadata Store (German National Library of Science and Technology)
op_collection_id ftdatacite
language unknown
topic 530 Physics
spellingShingle 530 Physics
Blaser, Patrick
Gutjahr, Marcus
Pöppelmeier, Frerk
Frank, Martin
Kaboth-Bahr, Stefanie
Lippold, Jörg
Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
topic_facet 530 Physics
description Deep waters of the Labrador Sea (LS) are important contributors to the Atlantic Meridional Overturning Circulation, but their water mass structure has been highly variable and sensitive to climatic changes on different time scales. The LS is also an area of intense exchange of rare earth elements (REE) between seawater and the underlying sediments, which complicates the reconstruction of past deep water provenance based on radiogenic neodymium (Nd) isotopes. Most notably, Northwest Atlantic Bottom Water exchanges Nd with Archaean age Laurentian detritus, resulting in a significant shift to less radiogenic Nd isotope signatures before it enters the North Atlantic to form the deep part of North Atlantic Deep Water. Here we show that the authigenic fractions of LS core top sediments carry Nd isotope signatures intermediate between bottom water and detritus and thus reflect pore waters that incorporate a mixture of both signatures. We furthermore find that detrital imprints on pore waters led to shifts of REE patterns in the authigenic fraction towards detrital signatures in the past during times of enhanced supply of glacially eroded material from Hudson Bay to the LS, as recorded by radiogenic lead isotopes. This allows an estimation of the intensity of past benthic REE exchange inside the LS. We exploit variations in the mid REE enrichment in the authigenic phase to propose a correction to one LS Nd isotope record for detrital imprints originating from pore water exchange. The corrected ϵNd signatures are argued to more accurately reflect those of past bottom waters. This correction results in past LS bottom water signatures of −16 ± 1 during MIS 2 and 3, considerably less radiogenic than today. This implies that no southern sourced waters advanced into the LS during the last 35 ka and instead supports continuous bottom water sourcing from the Nordic Seas. It thus seems likely that LS bottom waters supplied unradiogenic Nd to abyssal Glacial North Atlantic Bottom Water in the Northwest Atlantic, as was previously hypothesized.
format Text
author Blaser, Patrick
Gutjahr, Marcus
Pöppelmeier, Frerk
Frank, Martin
Kaboth-Bahr, Stefanie
Lippold, Jörg
author_facet Blaser, Patrick
Gutjahr, Marcus
Pöppelmeier, Frerk
Frank, Martin
Kaboth-Bahr, Stefanie
Lippold, Jörg
author_sort Blaser, Patrick
title Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
title_short Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
title_full Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
title_fullStr Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
title_full_unstemmed Labrador Sea bottom water provenance and REE exchange during the past 35,000 years
title_sort labrador sea bottom water provenance and ree exchange during the past 35,000 years
publisher Elsevier
publishDate 2020
url https://dx.doi.org/10.48350/158655
https://boris.unibe.ch/158655/
geographic Hudson
Hudson Bay
geographic_facet Hudson
Hudson Bay
genre Hudson Bay
Labrador Sea
Nordic Seas
North Atlantic Deep Water
North Atlantic
Northwest Atlantic
genre_facet Hudson Bay
Labrador Sea
Nordic Seas
North Atlantic Deep Water
North Atlantic
Northwest Atlantic
op_rights restricted access
publisher holds copyright
http://purl.org/coar/access_right/c_16ec
op_doi https://doi.org/10.48350/158655
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