Marine palynology: potentials for onshore—offshore correlation of Pleistocene—Holocene records

Abstract

A review of marine pollen-spore distributions reveals regional variations in primary transport pathways. Fluvial transport prevails on the mountainous margins of the eastern Pacific and off major river deltas, including Arctic estuaries. Elsewhere, wind and sea ice are the main transport agents, and pollen concentration corresponds to dust influx. Redeposition of Quaternary palynomorphs is also important near emergent continental ice sheet centres where fine-grained sediment is being eroded. Pre-Quaternary palynomorphs can indicate sources of ice-rafted debris. Preservation and transport of pollen in marine sediments is not well understood. Laboratory processing with acetolysis shows damage of bisaccate grains, and copepod feeding experiments show some pollen damage of grains within the faecal pellet membranes. A multi-box model shows the relative importance of rivers, wind and ocean currents in pollen transport to shelves of Atlantic Canada: most pollen is wind-transported, but large storms may indirectly increase influx. In the Arctic, sea ice scouring and sediment transport are important in addition to northeasterly winds. These glacial processes would impact a third of the planet during glaciations. Pleistocene cores from NW Atlantic and Pacific Oceans show that glacial stage transport differed from that during Holocene and other interglacials because glacioeustatic lowstands exposed the continental shelves, and wind strength and direction changed following ice sheet growth. Pollen influxes and ice-volume records show variable leads and lags of palaeometerological events at glacial/interglacial boundaries, with a major decline in terrigenous organics after ∼0.4 Ma (MIS 13-11).