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Christof Pearce

Insolation vs. meltwater control of productivity and sea surface conditions off SW Greenland during the Holocene

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DOI

  • Estelle Allan, GEOTOP, Université du Québec à Montréal
  • ,
  • Anne de Vernal, GEOTOP, Université du Québec à Montréal
  • ,
  • Marit Solveig Seidenkrantz
  • Jason P. Briner, University at Buffalo, The State University of New York
  • ,
  • Claude Hillaire-Marcel, GEOTOP, Université du Québec à Montréal
  • ,
  • Christof Pearce
  • Lorenz Meire, Greenland Institute of Natural Resources, Utrecht University
  • ,
  • Hans Røy
  • Anders Møller Mathiasen, Aarhus University, Institut for GeoScience, Aarhus Universitet, Denmark
  • Mikkel Thy Nielsen, Aarhus University, Institut for Geoscience, AU, Denmark
  • Jane Lund Plesner
  • Kerstin Perner, Leibniz Institute for Baltic Sea Research

We address here the specific timing and amplitude of sea-surface conditions and productivity changes off SW Greenland, northern Labrador Sea, in response to the high deglacial meltwater rates, the Early Holocene maximum insolation and Neoglacial cooling. Dinocyst assemblages from sediment cores collected off Nuuk were used to set up quantitative records of sea ice cover, seasonal sea-surface temperature (SST), salinity (SSS), and primary productivity, with a centennial to millennial scale resolution. Until similar to 10 ka BP, ice-proximal conditions are suggested by the quasi-exclusive dominance of heterotrophic taxa and low dinocyst concentrations. At about 10 ka BP, an increase in species diversity and abundance of phototrophic taxa marks the onset of interglacial conditions at a regional scale, with summer SST reaching up to 10 degrees C between 8 and 5 ka BP, thus in phase with the Holocene Thermal Maximum as recorded in the southern Greenlandic areas/northern Labrador Sea. During this interval, low SSS but high productivity prevailed in response to high meltwater discharge and nutrient inputs from the Greenland Ice Sheet. After similar to 5 ka BP, a decrease in phototrophic taxa marks a two-step cooling of surface waters. The first started at similar to 5 ka BP, and the second at similar to 3 ka BP, with a shift toward colder conditions and higher SSS suggesting reduced meltwater discharge during the Neoglacial. This second step coincides with the disappearance of the Saqqaq culture. The gap in human occupation in west Greenland, between the Dorset and the Norse settlements from 2000 to 1000 years BP, might be linked to high amplitude and high frequency variability of ocean and climate conditions.

Original languageEnglish
JournalBoreas
Volume50
Issue3
Pages (from-to)631-651
Number of pages21
ISSN0300-9483
DOIs
Publication statusPublished - Jul 2021

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