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Holocene water mass changes in the Labrador Current

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Dokumenter

DOI

  • Annalena Antonia Lochte, GEOMAR Helmholtz Ctr Ocean Res Kiel, Helmholtz Association, GEOMAR Helmholtz Center for Ocean Research Kiel
  • ,
  • Janne Repschlaeger, Max Planck Inst Chem Energiekonvers, Max Planck Society
  • ,
  • Marit-Solveig Seidenkrantz
  • Markus Kienast, Dalhousie Univ, Dalhousie University, Dept Oceanog
  • ,
  • Thomas Blanz, Univ Kiel, University of Kiel, Inst Geosci
  • ,
  • Ralph R. Schneider, Univ Kiel, University of Kiel, Inst Geosci

The Labrador Current is part of the anticlockwise subpolar gyre and plays a major role in the formation of North Atlantic Deep Water. It is influenced by the West Greenland and Baffin currents supplying warmer Atlantic and cold polar waters, respectively. During the early Holocene, at the final stage of the last deglaciation, meltwater and iceberg discharge caused highly variable conditions in the Labrador Current. In order to assess its sensitivity to such freshening, this study provides a well-resolved Holocene paleoclimatic record from the Labrador Shelf. Based on benthic foraminiferal faunal and alkenone biomarker analyses, we differentiated four distinct climatic periods in the western Labrador Sea. From 8.9 to 8.6 ka BP, the Labrador Shelf was dominated by polar water outflow from Baffin Bay and covered by perennial sea ice. Between 8.6 and 7.4 ka BP, a strong subsurface inflow of warmer Atlantic water masses is ascribed to an intensification and redirection of the West Greenland Current. At 7.4 ka BP, the decreased influence of Atlantic water masses on the Labrador Shelf marks the establishment of winter convection leading to the formation of Labrador Sea Water in the central basin. Concurrently, an intensified polar water outflow through the Canadian Gateways strengthened the inner Labrador Current, and higher primary productivity suggests longer spring blooms because of a shorter sea-ice season during the Holocene Thermal Maximum. In the late Holocene after 3 ka BP, periodic fluctuations of primary productivity may tentatively be correlated with stronger and weaker northwesterly winds.

OriginalsprogEngelsk
TidsskriftHolocene
Vol/bind29
Nummer4
Sider (fra-til)676-690
Antal sider15
ISSN0959-6836
DOI
StatusUdgivet - apr. 2019

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