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TitreLabrador Current fluctuation during the last glacial cycle
AuteurMao, L; Piper, D J W; Saint-Ange, F; Andrews, J T
SourceMarine Geology vol. 395, 2018 p. 234-246, https://doi.org/10.1016/j.margeo.2017.10.012
Année2018
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130248
ÉditeurElsevier
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1016/j.margeo.2017.10.012
Mediapapier; en ligne; numérique
Formatspdf
ProvinceRégion extracotière de l'est
Lat/Long OENS-110.0000 20.0000 80.0000 40.0000
Sujetsréseaux de circulation de l'eau; carottes de sédiment marin; analyses par diffraction des rayons x; dolomites; calcite; isotopes d'oxygène; datations au radiocarbone; géologie marine
Illustrationslocation maps; lithologic logs; tables; graphs
ProgrammeRisques géo marines, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
Records from cores 2011031-059 and 2011031-062 (hereafter 59 and 62) have been used to reconstruct changes in the vigor of the Labrador Current in northern Flemish Pass during the last glacial cycle. Grain size proxies for current speed, planktonic foramiferal delta18O, X-ray diffraction analysis for dolomite and calcite, and abundance of ice-rafted detritus (IRD) have been determined. An age model back to Marine Isotope Stage (MIS) 5 is based on recognition of seven Heinrich events from total dolomite and calcite, correlated to the IODP U1302/3 record, and confirmed by O-isotope stratigraphy and radiocarbon dates. A straight-line relationship between mean size of sortable silt (SS) and percent of sortable silt (SS%) and the lack of relationship between SS and IRD (> 500 um) indicate well-sorted sediments in cores 59 and 62, which can be used to reconstruct the paleocurrent intensity. Intensified current vigor occurred in MIS 5, 3 and 1, so that warmer periods show faster currents, probably through the Irminger Current component of the North Atlantic subpolar gyre. Low values of delta18O, SS% and SS correspond to H events, suggesting a slowdown in the Labrador Current, followed by a rapid return to strong circulation. In some cases current vigor recovery lagged slightly after the H events. Heinrich events with larger amounts of meltwater show higher current vigor. Correlation with deep-water current vigor records in the Iceland Basin show a broad correlation on a multi-millennial scale with Labrador Current variations. As our study is on a shallow sediment drift formed by the Labrador Current, one of the surface currents of the North Atlantic sub-polar gyre, it provides new evidence for a tight connection between surface current vigor fluctuation and the vigor of the deep thermohaline circulation.
Résumé(Résumé en langage clair et simple, non publié)
À partir d'une longue carotte prélevée dans la passe Flamande, on a pu observer les changements de débit du courant du Labrador survenus depuis 115 000 ans. La vitesse du courant est un facteur essentiel dans la détermination des propriétés géotechniques des sédiments près du champ pétrolifère Mizzen. Elle est très utile pour prédire quel type de sédiment se trouve à des profondeurs trop grandes pour qu'on puisse y prélever des échantillons.
GEOSCAN ID293082