OCEANIC POLLEN TRANSPORT AND POLLEN DINOCYST RATIOS AS MARKERS OF LATE CENOZOIC SEA-LEVEL CHANGE AND SEDIMENT TRANSPORT/

Palynological studies of late Cenozoic cores from nine sites show larg e peaks in the ratio of pollen and spores to dinocysts (P:D) which ref lect major increases in terrigenous sediment influx to the North Atlan tic Ocean. Under normal pelagic conditions in the North Atlantic, i.e. , in the absence of ice rafting or mass wasting, P:D in oceanic sedime nts is low, usually <0.5. Geographic and temporal variation in P:D sug gests that mass wasting during glacioeustatic sea level lowstands (col d isotopic stages) was the main source of these large pollen inputs to the deep sea during the latest Pliocene to Pleistocene. Pollen and sp orts, mostly deposited on continental shelves es during interglacial s ea level highstands, are resuspended during lowstands and transported across the margins by turbidity currents and over the abyss by ocean c urrents. Peaks in P:D in deep sea sediments thus correlate with erosio nal unconformities that bound sequences on continental margins. These peaks of late Cenozoic pollen-spore influx are usually distinct from i ntervals of ice-rafted sediment deposition which are marked by large i nfluxes of Mesozoic-Paleogene dinocysts of probable Norwegian Trough o rigin and Paleozoic acritarchs from bedrock eroded by Canadian Arctic glaciers. (C) 1998 Elsevier Science B.V.