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 large peaks in the ratio of pollen and spores to dinocysts (P:D) which reflect major increases in terrigenous sediment influx to the North Atlantic Ocean. Under normal pelagic conditions in the North Atlantic, i.e., in the absence of ice rafting or mass wasting, P:D in oceanic sediments is low, usually <0.5. Geographic and temporal variation in P:D suggests that mass wasting during glacioeustatic sea level lowstands (cold isotopic stages) was the main source of these large pollen inputs to the deep sea during the latest Pliocene to Pleistocene. Pollen and spores, mostly deposited on continental shelves during interglacial sea level highstands, are resuspended during lowstands and transported across the margins by turbidity currents and over the abyss by ocean currents. Peaks in P:D in deep sea sediments thus correlate with erosional unconformities that bound sequences on continental margins. These peaks of late Cenozoic pollen-spore influx are usually distinct from intervals of ice-rafted sediment deposition which are marked by large influxes of Mesozoic-Paleogene dinocysts of probable Norwegian Trough origin and Paleozoic acritarchs from bedrock eroded by Canadian Arctic glaciers.