HR: 0800h
AN: PP21C-1586    [Abstracts]
TI: Straddling the Eirik Drift: Implications from the History of Lower NADW
AU: * Neitzke, L C
EM: lneitzke@eden.rutgers.edu
AF: Rutgers University, Department of Geological Sciences 610 Taylor Road, Piscataway, NJ 08854 United States
AU: Wright, J D
EM: jdwright@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences 610 Taylor Road, Piscataway, NJ 08854 United States
AU: Mountain, G S
EM: gmtn@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences 610 Taylor Road, Piscataway, NJ 08854 United States
AU: Manley, P L
EM: patmanley@middlebury.edu
AF: Middlebury College, 427 McCardell Bicentennial Hall, Middlebury, VT 05753 United States
AB: The Eirik Drift is located 50 to 350 km off the southern tip of Greenland. It forms as south-flowing lower North Atlantic Deep Water (LNADW) turns west into the Labrador Sea, slows, and deposits suspended sediment. These sediments provide a valuable paleoclimate record because of their high accumulation rates, proximity to the Greenland ice sheet, and the signature of changes in NADW. Cruise Kn166-14 collected high-resolution seismic, swath, and core data on Eirik Drift. A pair of cores was collected from near the distal end of the drift, straddling the drift crest at water depths of C3200 m. Core 18JPC (on the SE side where current speeds are at present faster) and 19JPC (the NW, slower side) were analyzed for planktonic foraminiferal stable isotopes, %CaCO3, and % lithics to evaluate changes in the flow of LNADW and climate. In Core 19JPC, Holocene sedimentation rates are >15 cm/kyr, whereas the average rate during Marine Isotope Chron (MIC) Stages 2-4 were ~10 cm/kyr. The highest sedimentation rates in this core occurred in Stage 5a-5d, of which ~9m of sediment were recovered. In contrast, no sediments of this age were preserved on the current side (18JPC) of the drift during the extreme interglacial MIC 1, 5e, and 7. However, ~8 m of sediments representing MIC 5a-5d were recovered at Core 18JPC. High accumulation rates (~15 cm/kyr) occurred at both sites during MIC 5a-5d, indicating that a strong NADW across Eirik Drift existed but did not reach as deep as 3200 m. These data show also that only during the extreme interglacials did LNADW penetrate to 3200m on the Eirik drift. Thus, this pair of cores used in this study indicates at least 3 states exist in the thermohaline system. A strong deep penetrating current that erodes the SE flank is found only during the extreme interglacials. A moderate flow that is evident in MIC 5a-5d and possibly MIC 3 resulting in enhanced current controlled deposition at both sites. And finally, a glacial mode in which the deep North Atlantic current shoaled significantly above this site such that little sedimentation results from the bottom currents.
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4940 Isotopic stage
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005