HR: 0800h
AN: PP41C-0686    [Abstracts]
TI: Increased Sensitivity of Northern Component Water on Millennial Scales During Glacial Intervals
AU: * Henderson, S S
EM: samhend@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences 610 Taylor Rd, Piscataway, NJ 08854, United States
AU: Wright, J D
EM: jdwright@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences 610 Taylor Rd, Piscataway, NJ 08854, United States
AU: Manley, P L
EM: manley@middlebury.edu
AF: Middlebury College, Department of Geology 427 McCardell Bicentennial Hall, Middlebury, VT 05753, United States
AB: The North Atlantic is a highly sensitive recorder of the Earth's climatic history partially due to Northern Component Water (NCW) formation in the Norwegian, Greenland and Labrador seas. Previous studies show strong correlations between abrupt climatic events such as Heinrich Events and perturbations in thermohaline circulation, particularly in areas regionally influenced by NCW formation. We present a record of NCW flow during the late Pleistocene from two sites drilled to the south of Greenland during IODP Expedition 303. Sites U1305 and U1306 are located on the flank of Eirik Drift at depths of 3459 m and 2274 m, respectively. The combination of mean sortable silt records at Sites U1305 and U1306 yield a high-resolution record (100 to 300 yr temporal resolution) of NCW flow strength and position from the last glacial maximum to present. Our results show a bimodal relationship in NCW buoyancy and flow position on Eirik Drift over the last glacial cycle. The glacial interval is characterized by high sedimentation rates over Site U1306 and is interpreted as a more buoyant NCW water mass. The interglacial interval shows high sedimentation rates over Site U1305 and is interpreted to be a less buoyant NCW water mass. An important observation in the sedimentation patterns on Eirik Drift is that the deepening of NCW over Eirik Drift lagged the onset of the interglacial by ~2 kyr. The expanded glacial interval (MIS 2-4) at Site U1306 records a series of cycles in the sortable silt record. These cycles are well defined and have durations of 1 to 3 kyr. In contrast, the Holocene sortable silt record from the deeper site shows cycles of similar duration, but with smaller amplitudes. The glacial cycles infer that the intensity and locus of NCW was more sensitive to climate variability. We attribute this sensitivity to the proximity of large terrestrial ice sheet and its capability to alter the fresh water contribution to this region.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting