High resolution stratigraphy of the Faeroe-Shetland Channel and its relation to North Atlantic paleoceanography: the last 87 kyr

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Two piston cores from the Faeroe-Shetland Channel have been investigated for stratigraphic and paleoceanographic correlation with Atlantic Ocean and Norwegian Sea records. The high resolution cores have been analyzed for the downcore distribution of planktic and benthic foraminifera and oxygen isotopes. AMS 14C dates and the position of Ash layers I and II form the basis for the correlation. Core NA81-10 covers the period from isotope stage 3 to Recent (stage 1), while core NA81-04 covers isotope stages 5a to 1. The Holocene is well represented in core NA81-10 by 2 m of sediment, whereas it is only 50 cm in core NA81-04 which is situated directly under the main core of the Norwegian Sea Deep Water outflow. The transition of isotope stage 2 to stage 1 is affected by dissolution and thus is less clearly represented. AMS 14C dates show that Termination IA begins at 16 ka and ends at about the 13 ka level. The Last Glacial Maximum (LGM; defined at 19-16 ka) is characterized by an IRD peak, faunal (planktic foraminifera) maxima (dated at 17.3 and 18.25 ka) and a high percentage of Globigerina quinqueloba. Apparently open water conditions and circulation within the Norwegian Sea prevailed at least from 22.5 to 14.8 ka, during the greatest part of stage 2 (including the LGM) and well onto Termination IA. A preservation maximum is observed throughout stage 2. Isotope stage 3, with a nearly complete record of isotope substages is well represented in both cores. Oxygen isotope depletion peaks correlate with fauna minima and in time to North Atlantic Heinrich events (H5-H1). Faunal data indicate that deep water is generated within the Norwegian-Greenland Sea repeatedly since 26 ka, with stops prior to 26 ka, 22.5–20.8/20.5 ka and between 14.9 and 13 ka (H3, H2 and H1). All isotope depletion peaks since ca. 50 ka are anticorrelated with fauna and are mainly controlled by surface salinity changes. Isotope stages and substages are directly correlated to fauna peaks and temperature between 87 and ca. 50 ka. The Faeroe-Shetland Channel record shows that repeated presences of Atlantic Surface Water and deep convection alternating with convection shutdowns have occurred within the Norwegian Sea-Greenland Sea from the beginning of stages 5a to 1.