Palynomorph concentrations in ODP Hole 105-645B samples (Table 1)

Significant changes in terrestrial and marine environments of Baffin Bay occurred throughout the late Pliocene to Holocene. Upper Pliocene and lowermost Pleistocene sediments contain abundant pollen and spores, which indicates the existence of open, coniferous, boreal forest to forest tundra in areas surrounding Baffin Bay. The late Pliocene-earliest Pleistocene also is characterized by relatively rich, dinoflagellate cyst and acritarch assemblages of boreal character, in which the dominance of Cymatiosphaera and Peridiniaceae may indicate neritic influx of sediments. In contrast, the late-early Pleistocene to Holocene interval is marked by a sparse terrestrial and marine palynoflora, with rare productive intervals. The general paucity of the Pleistocene palynoflora suggests low primary productivity, both on land and offshore, probably caused by cold, dry, high arctic conditions.

Stratigraphic occurrence of selected marine palynomorph species recorder in the Paleogene of ODP Hole 105-647A (Table 3)

Dinoflagellate cysts were recovered throughout the Paleogene succession of Hole 647A, which contains an almost complete deep-water record of early Eocene through early late Oligocene sedimentation in the Labrador Sea. Dinoflagellate cyst biostratigraphy is in general accord with that provided by other microfossil groups and is consistent with a lower Eocene age, as determined by nannofossils, for basal sediments in Hole 647A. These sediments overlie oceanic crust of Chron 24 age. Dinocyst assemblages indicate outer neritic to oceanic conditions throughout, although the persistent occurrence of Wetzeliellaceae specimens in the lower Eocene suggests a greater influence from shelf environments during this time. Lower Eocene dinocyst assemblages are similar to coeval assemblages from the Rockall Plateau, but those from the middle to upper Eocene have mixed affinities and may be related to the intensification of the proto-Gulf Stream from middle Eocene time. Oligocene dinocyst assemblages suggest the influence of both arctic and North Atlantic wate rmasses at this site. The presence of protoperidineacean species in the upper Eocene and Oligocene may indicate increased availability of nutrients, perhaps related to increased upwelling or the effects of water-mass mixing. Productive samples are dominated by dinocysts and acritarchs, while sporomorphs are represented mainly by bisaccate pollen. Preservational differences within samples may reflect mixing of penecontemporaneous dinocyst populations during the Eocene, and all samples examined may have a considerable allochthonous component. Variability in relative abundance of many species during the Eocene may be related to fluctuating water-mass properties. A total 175 dinocyst and acritarch taxa were recorded from 53 productive samples from the Paleogene. Only one Paleogene sample was barren of palynomorphs. Of three Miocene samples processed, all were barren.