Variations in Atlantic surface ocean paleoceanography, 50ø-80øN: A time-slice record of the last 30,000 years - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Paleoceanography Année : 1995

Variations in Atlantic surface ocean paleoceanography, 50ø-80øN: A time-slice record of the last 30,000 years

Maurice Arnold
  • Fonction : Auteur
  • PersonId : 938257
Michael Samthein
  • Fonction : Auteur
Jean Duplessy
  • Fonction : Auteur
Astrid Flat0y
  • Fonction : Auteur

Résumé

Eight time slices of surface-water paleoceanography were reconstructed from stable isotope and paleotemperature data to evaluate late Quaternary changes in density, current directions, and sea-ice cover in the Nordic Seas and NE Atlantic. We used isotopic records from 110 deep-sea cores, 20 of which are accelerator mass spectrometry (AMS)-14C dated and 30 of which have high (>8 cm/kyr) sedimentation rates, enabling a resolution of about 120 years. Paleotemperature estimates are based on species counts of planktonic foraminifera in 18 cores. The •5180 and •513C distributions depict three main modes of surface circulation: (1) The Holocene-style interglacial mode which largely persisted over the last 12.8 •4C ka, and probably during large parts of stage 3. (2) The peak glacial mode showing a cyclonic gyre in the, at least, seasonally ice-free Nordic Seas and a meltwater lens west of Ireland. Based on geostrophic forcing, it possibly turned clockwise, blocked the S-N flow across the eastern Iceland-Shetland ridge, and enhanced the Irminger current around west Iceland. It remains unclear whether surface-water density was sufficient for deepwater formation west of Norway. (3) A meltwater regime culminating during early glacial Termination I, when a great meltwater lens off northern Norway probably induced a clockwise circulation reaching south up to Faeroe, the northward inflow of Irminger Current water dominated the Icelandic Sea, and deepwater convection was stopped. In contrast to circulation modes two and three, the Holocene-style circulation mode appears most stable, even unaffected by major meltwater pools originating from the Scandinavian ice sheet, such as during •80 event 3.1 and the B611ing. Meltwater phases markedly influenced the European continental climate by suppressing the "heat pump" of the Atlantic salinity conveyor belt. During the peak glacial, melting icebergs blocked the eastward advection of warm surface water toward Great Britain, thus accelerating buildup of the great European ice sheets; in the early deglacial, meltwater probably induced a southward flow of cold water along Norway, which led to the Oldest Dryas cold spell.
Fichier principal
Vignette du fichier
Paleoceanography - December 1995 - Sarnthein - Variations in Atlantic surface ocean paleoceanography 50 ‐80 N A.pdf (3.98 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-03609307 , version 1 (15-03-2022)

Identifiants

Citer

Michael Sarnthein, Eystein Jansen, Mara Weinelt, Maurice Arnold, Jean Claude Duplessy, et al.. Variations in Atlantic surface ocean paleoceanography, 50ø-80øN: A time-slice record of the last 30,000 years. Paleoceanography, 1995, 10 (6), pp.1063-1094. ⟨10.1029/95PA01453⟩. ⟨hal-03609307⟩

Collections

CEA CNRS
23 Consultations
37 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More