Neogene benthic foraminifer biostratigraphy and deep-water history of sites 645, 646, and 647, Baffin Bay and Labrador Sea

Benthic foraminifers were examined from Neogene sediments of Ocean Drilling Program (ODP) Sites 645, 646, and 647 to determine their biostratigraphy and to place constraints on the paleoceanographic history of Baffin Bay, Eirik Ridge, and the Gloria Drift. At Site 645 in Baffin Bay, a Pleistocene Stetsonia assemblage is similar to the modern Baffin Bay assemblage, but an underlying Epistominella takayanagii assemblage has no modern analog. Miocene assemblages below a barren interval display low diversity and consist mainly of agglutinated species. At Site 646 in the Labrador Sea, benthic faunal turnovers occur near important seismic horizons. A Miocene Nuttallides umbonifera assemblage similar to assemblages at other North Atlantic sites occurs below reflector R3. Above reflector R3, a coarse agglutinated assemblage containing more diversified calcareous benthic foraminifers was found that displays affinity to assemblages in the Norwegian-Greenland Sea. The faunal turnover near reflector R3 was interpreted as reflecting the onset (or renewal) of significant Denmark Straits Overflow Water at Site 646 at ~7.5 Ma, Agglutinated species disappear between reflector R2 and the base of the sediment drift, indicating a change in deep-water properties that occurred at ~ 4.7 Ma. This turnover ultimately may be linked to the reopening of the Mediterranean. The beginning of drift sedimentation at the Eirik Ridge is dated at —4.5 Ma. Drift formation ceased at ~2.5 Ma, concomitant with the appearance of ice-rafted sediments. Pleistocene assemblages containing Stetsonia horvathi display affinity to deep assemblages in high-latitude ocean basins. Upper Pliocene and Pleistocene benthic assemblages at Site 647 contain N. umbonifera, which indicates a continued influence of corrosive deep water at the Gloria Drift.