Nordic Seas and Subarctic Atlantic water masses traced by neodymium isotopes

• Main Author: Lacan, F.
• Other Authors: GEOMAR LEGOS, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier - Toulouse III, Catherine Jeandel
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2002
• Subjects: isotopic tracers; North Atlantic; water masses; neodymium; interactions continent/océan; traceurs isotopiques; boundary exchange; masses d'eau; érosion; néodyme; Atlantic Nord; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Greenland; Norwegian Sea; Groenland; Iceland; Islande; NADW; Nordic Seas; North Atlantic Deep Water; North East Atlantic; Subarctic; subarctique*
• Online Access: https://tel.archives-ouvertes.fr/tel-00118162; https://tel.archives-ouvertes.fr/tel-00118162/document; https://tel.archives-ouvertes.fr/tel-00118162/file/theserv.pdf

The neodymium isotopic composition (Nd I.C.) is a tracer of oceanic circulation and of ocean/continent matter exchanges. We measured this parameter in almost 200 seawater samples from the Nordic Seas (Greenland, Iceland and Norwegian) and the Subarctic Atlantic (north of 50°N). The interpretation of these data in relation with the hydrology and the geology of the studied area allowed to improve our knowledge of the circulation and the tracer Nd CI. The study of the isotopic signature of the Subarctic Intermediate Water (SAIW), the Norwegian Sea Deep Water and the Subpolar Mode Water (SPMW) allowed us to better understand their history (pathways, mixings). In particular, we confirm the SAIW originates in the Labrador Current and we suggest that the SPMW is the result of a two end-member mixture : Central North Atlantic Water and waters from the Labrador Current. Nd I.C. are in good agreement with the commonly accepted scenarios of the formation of the upper and lower layers of the North Atlantic Deep Water (NADW). On the other hand they suggest a North East Atlantic Deep Water composition significantly different from that of the middle layer of the NADW. This point will require further studies. We firmly confirm that the Nd IC is conservative in the absence of terrigeneous input. We show the influence of granitic derived sediments on water masse Nd I.C. and confirm that of basaltic derived sediments. We suggest that the Nd IC partially lost the memory of water mass history during sediment/ocean interactions, within high hydraulic energy areas. Lastly, we suggest that passed erosion variations would modify NADW signature as much as or maybe more than circulation variations. La composition isotopique de néodyme (C.I. de Nd) est un traceur de circulation océanique et d'échanges de matière océan/continent. Nous avons mesuré cette grandeur sur près de 200 échantillons d'eau de mer des mers Nordiques (Groenland, Islande, Norvège) et de l'Atlantique Subarctique (au nord de 50°N). L'interprétation de ces données en ...