Structure of the upper water column in the northwest North Atlantic: Modern versus Last Glacial Maximum conditions

  • de Vernal A
  • Hillaire-Marcel C
  • Peltier W
 et al. 
  • 37


    Mendeley users who have this article in their library.
  • 29


    Citations of this article.


During the Last Glacial Maximum, the northwestern North Atlantic constituted a major conduit for Labrador and Greenland ice sheet meltwaters. Vertical density gradients in its upper water masses have been reconstructed by combining information from transfer functions based on dinocysts and from oxygen isotope measurements (d18O) in planktonic foraminifera. Transfer functions yield temperature and salinity and thus potential density (sq) for the warmest (August) and coldest (February) months in the photic zone. The d18O values in different size fractions of epipelagic (Globigerina bulloides) and mesopelagic (Neogloboquadrina pachyderma left-coiled (Npl)) foraminifera allow us to assess sq gradients through the pycnocline between surface and intermediate waters, based on the calibration of a sq versus d18O relationship from transfer function reconstructions. The size and density of Npl shells provide further constraints on these sq gradients. The results show the development of a very strong pycnocline during the LGM with a difference of about 3 (summer) to 1.5 (winter) sq units between surface and underlying waters. They indicate conditions unfavorable for vertical convection and support the hypothesis of the spreading of a shallow, low-salinity buoyant layer over the northern North Atlantic. This layer depicted a strong E-W gradient, with maximum seasonal contrast and minimum absolute sq values westward.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Anne de Vernal

  • Claude Hillaire-Marcel

  • W. Richard Peltier

  • Andrew J. Weaver

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free