Modern and late Quaternary pollen spectra of fiord sediments, eastern Baffin Island, Arctic Canada

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Pollen spectra of thirty surface samples from Baffin Island fiords are dominated by a Betula/Filicales/Cyperaceae/Gramineae association that is somewhat representative of local or regional vegetation. However, Betula and Filicales are over-represented and Salix, Cyperaceae and Ericales are under-represented compared to their importance in the present vegetation. Two possible causes for this disparity, related to the fluvial processes that furnish most pollen to fiords, are: (1) fluvial reworking of older sediment that contains abundant Betula and Filicales; and (2) greater resistance of these taxa to corrosion and degradation during fluvial transport. The pollen stratigraphy of five piston cores from fiords contains two types of pollen assemblages. In the lower portions of the cores, exotic pollen types and pre-Quaternary palynomorphs are abundant. The upper portions of the cores contain an assemblage roughly representative of the present vegetation, in which Cyperaceae and Gramineae are abundant and exotic and pre-Quaternary types are reduced or absent. The lower assemblage was deposited during the late glacial/deglacial transition and deglaciation ca. 12,000 to 6000 B.P., when eastern Baffin Island had little vegetation cover and long-distance transport and reworking were virtually the only pollen sources. A feature of several cores is a major peak in Dinoflagellates about 5000 B.P. This event may be related to the postglacial marine climatic optimum in the eastern Canadian Arctic between 5000 and 3000 B.P.