A. Rochon et A. Devernal, PALYNOMORPH DISTRIBUTION IN RECENT SEDIMENTS FROM THE LABRADOR SEA, Canadian journal of earth sciences, 31(1), 1994, pp. 115-127
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.