Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise
International audience Contourite sediment accumulations at continental margins are related to strong bottom water circulation, where intense winnowing can result in neoformation of authigenic grains of glauconite at the seafloor. In this study, we investigated whether such glauconite grains could f...
Published in: | Frontiers in Earth Science |
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ftunivperpignan:oai:HAL:insu-03691024v1 2023-10-01T03:57:27+02:00 Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise Giresse, Pierre Bayon, Germain Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM) Université de Perpignan Via Domitia (UPVD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) 2021 https://insu.hal.science/insu-03691024 https://insu.hal.science/insu-03691024/document https://insu.hal.science/insu-03691024/file/feart-09-652501-1.pdf https://doi.org/10.3389/feart.2021.652501 en eng HAL CCSD Frontiers Media info:eu-repo/semantics/altIdentifier/doi/10.3389/feart.2021.652501 insu-03691024 https://insu.hal.science/insu-03691024 https://insu.hal.science/insu-03691024/document https://insu.hal.science/insu-03691024/file/feart-09-652501-1.pdf BIBCODE: 2021FrEaS.9.228G doi:10.3389/feart.2021.652501 http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess ISSN: 2296-6463 Frontiers in Earth Science https://insu.hal.science/insu-03691024 Frontiers in Earth Science, 2021, 9, ⟨10.3389/feart.2021.652501⟩ Rare Earth Elements Neodymium isotopes glauconitisation Demerara Contourite [SDU]Sciences of the Universe [physics] [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2021 ftunivperpignan https://doi.org/10.3389/feart.2021.652501 2023-09-05T22:42:09Z International audience Contourite sediment accumulations at continental margins are related to strong bottom water circulation, where intense winnowing can result in neoformation of authigenic grains of glauconite at the seafloor. In this study, we investigated whether such glauconite grains could faithfully record ambient bottom-water neodymium (Nd) isotopic compositions, and hence be used as paleoceanographic archives. To this purpose, we measured Nd isotopic compositions (Nd) in a series of glauconitic grains, foraminiferal assemblages, leached Fe-Mn oxyhydroxide phases and detrital clays separated from a contourite sediment record at the Demerara slope off French Guiana (IG-KSF-11; 2370 m water depth), at a location where the present-day Nd distribution along the water column is well characterized. We show that the Nd composition of core-top glauconite grains (-12.0 ± 0.5) agrees with the expected NADW-like seawater signature at the same location and water depth (-11.6 ± 0.3), while departing from measured Nd values for corresponding detrital clays (-11.3 ± 0.2), foraminiferal (-10.9 ± 0.2) and Fe-Mn oxyhydroxide fractions (-9.2 ± 0.2). This finding indicates that glauconitic grains at this particular location are probably best suited for paleoceanographic reconstructions than foraminifera and leached Fe-oxyhydroxide fractions, which appear to be influenced by sediment redistribution and the presence of terrestrial continental Fe-oxides, respectively. Using rare earth elements (REE), we tentatively propose that the acquisition of seawater Nd isotopic signatures by glauconite is controlled by the presence of authigenic REE-bearing phosphate-rich phases intertwined within clay mineral sheets, while confirming previous findings that the process of glauconitisation results in the progressive loss of REE within glauconitic grains. Preliminary paleoceanographic implications suggest strengthened bottom-water circulation of the glacial analogue of NADW at this particular location and water depth, with a Nd ... Article in Journal/Newspaper NADW Université de Perpignan: HAL Frontiers in Earth Science 9 |
institution |
Open Polar |
collection |
Université de Perpignan: HAL |
op_collection_id |
ftunivperpignan |
language |
English |
topic |
Rare Earth Elements Neodymium isotopes glauconitisation Demerara Contourite [SDU]Sciences of the Universe [physics] [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
Rare Earth Elements Neodymium isotopes glauconitisation Demerara Contourite [SDU]Sciences of the Universe [physics] [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Giresse, Pierre Bayon, Germain Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise |
topic_facet |
Rare Earth Elements Neodymium isotopes glauconitisation Demerara Contourite [SDU]Sciences of the Universe [physics] [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience Contourite sediment accumulations at continental margins are related to strong bottom water circulation, where intense winnowing can result in neoformation of authigenic grains of glauconite at the seafloor. In this study, we investigated whether such glauconite grains could faithfully record ambient bottom-water neodymium (Nd) isotopic compositions, and hence be used as paleoceanographic archives. To this purpose, we measured Nd isotopic compositions (Nd) in a series of glauconitic grains, foraminiferal assemblages, leached Fe-Mn oxyhydroxide phases and detrital clays separated from a contourite sediment record at the Demerara slope off French Guiana (IG-KSF-11; 2370 m water depth), at a location where the present-day Nd distribution along the water column is well characterized. We show that the Nd composition of core-top glauconite grains (-12.0 ± 0.5) agrees with the expected NADW-like seawater signature at the same location and water depth (-11.6 ± 0.3), while departing from measured Nd values for corresponding detrital clays (-11.3 ± 0.2), foraminiferal (-10.9 ± 0.2) and Fe-Mn oxyhydroxide fractions (-9.2 ± 0.2). This finding indicates that glauconitic grains at this particular location are probably best suited for paleoceanographic reconstructions than foraminifera and leached Fe-oxyhydroxide fractions, which appear to be influenced by sediment redistribution and the presence of terrestrial continental Fe-oxides, respectively. Using rare earth elements (REE), we tentatively propose that the acquisition of seawater Nd isotopic signatures by glauconite is controlled by the presence of authigenic REE-bearing phosphate-rich phases intertwined within clay mineral sheets, while confirming previous findings that the process of glauconitisation results in the progressive loss of REE within glauconitic grains. Preliminary paleoceanographic implications suggest strengthened bottom-water circulation of the glacial analogue of NADW at this particular location and water depth, with a Nd ... |
author2 |
Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM) Université de Perpignan Via Domitia (UPVD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) |
format |
Article in Journal/Newspaper |
author |
Giresse, Pierre Bayon, Germain |
author_facet |
Giresse, Pierre Bayon, Germain |
author_sort |
Giresse, Pierre |
title |
Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise |
title_short |
Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise |
title_full |
Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise |
title_fullStr |
Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise |
title_full_unstemmed |
Neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from Demerara Rise |
title_sort |
neodymium isotopes in glauconite for palaeoceanographic reconstructions at continental margins: a preliminary investigation from demerara rise |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://insu.hal.science/insu-03691024 https://insu.hal.science/insu-03691024/document https://insu.hal.science/insu-03691024/file/feart-09-652501-1.pdf https://doi.org/10.3389/feart.2021.652501 |
genre |
NADW |
genre_facet |
NADW |
op_source |
ISSN: 2296-6463 Frontiers in Earth Science https://insu.hal.science/insu-03691024 Frontiers in Earth Science, 2021, 9, ⟨10.3389/feart.2021.652501⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.3389/feart.2021.652501 insu-03691024 https://insu.hal.science/insu-03691024 https://insu.hal.science/insu-03691024/document https://insu.hal.science/insu-03691024/file/feart-09-652501-1.pdf BIBCODE: 2021FrEaS.9.228G doi:10.3389/feart.2021.652501 |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.3389/feart.2021.652501 |
container_title |
Frontiers in Earth Science |
container_volume |
9 |
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1778528758153609216 |