PALYNOMORPH DISTRIBUTION IN RECENT SEDIMENTS FROM THE LABRADOR SEA

Surface sediments from the Labrador Sea and Baffin Bay have been exami ned for their palynomorph content. Pollen and spore assemblages reflec t the vegetation zones of eastern Canada, although long-distance atmos pheric transport results in over-representation of Pinus and spores. A linear decrease of pollen input is observed with distance from the so urce vegetation; the abyssal domain receives less than 2% of the initi al input. The abundance of dinoflagellate cysts reflects a relatively high primary productivity in surface water masses which seems proporti onal to the benthic productivity, as shown by the concentrations of or ganic linings of foraminifers. The relative abundance of dinoflagellat e cyst taxa and principal component analysis led to the definition of three assemblages that can be related to sea-surface conditions and cu rrent pattern. The modern distribution of dinoflagellate cysts was use d to interpret assemblages recovered in five box cores from the deep L abrador Sea. Results reveal important changes in sea-surface condition s during the Holocene. At the end of the last glacial period, the prod uctivity in surface waters was sparse, notably on the continental slop e off southwest Greenland. Shortly after the deglaciation, the primary productivity increased, probably due to the improvement of sea-surfac e conditions. At about 5000 BP, the dinoflagellate cyst concentrations and fluxes reach maximum values, and the assemblages are marked by th e augmentation of Nematosphaeropsis labyrinthus relative to Operculodi nium centrocarpum. This trend is associated with a cooling and the inc reased influence of the inner component of the Greenland Current in su rface water masses of the Labrador Sea. It marks the establishment of modern conditions in the basin.