Neogene Benthic Foraminifer Biostratigraphy and Deep-Water History of Sites 645, 646, and 647, Baffin Bay and Labrador Sea

Abstract

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-wa ter 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, con comitant with the appearance of ice-rafted sediments. Pleistocene assemblages containing Stetsonia horvathi display af finity 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.

Updates

“…The prominence of agglutinated benthic foraminifera, which are more environmentally tolerant than calcareous species, is also consistent with a food-rich inner shelf environment corrosive to small calcitic tests. All microfossil assemblages have environmental and climatic affinities comparable to assemblages observed in the Miocene of western Baffin Bay and the Labrador Sea (ODP Leg 105) and the North Sea (Kaminski et al, 1989;King, 1989).…”

Morris Jesup Spur and Rise north of Greenland – exploring present seabed features, the history of sediment deposition, volcanism and tectonic deformation at a Late Cretaceous/early Cenozoic triple junction in the Arctic Ocean

“…2). Our estimated delayed submergence of the spur during the latest Miocene-earliest Pliocene appears to coincide in time with accelerated build-up of the Erik Ridge south of Greenland at ̴ 4.5 Ma (Arthur et al, 1989;Kaminski et al, 1989;Müller-Michaels et al, 2013), suggesting a possible connection between submergence of the spur and the intensification of the East Greenland Current.…”

“…The emergence and relative intensity of the East Greenland Current has been inferred from growth of the Erik Drift, a more than 1.5 km-high and over 400 km-long ridge of sediment deposited out from the continental slope at the southern tip of Greenland by contour-following bottom currents (Arthur et al, 1989). Initiation of sediment drift deposits in the area may have begun in the early Miocene (Müller-Michaels et al, 2013), but accelerated at ˞4.5 Ma (Kaminski et al, 1989;Wold, 1994;Hunter et al, 2007). Another major Neogene oceanographic event in the Arctic Ocean is the opening of the Fram Strait which is manifested as a transition from an oxygen-poor basin to a state of ventilated circulation after about 17.5 Ma (Jakobsson et al, 2007).…”