HR: 1340h
AN: PP13B-1280    [Abstracts]
TI: Northern Component Water Variability Over the Past 21 kyr: High-resolution Records From Eirik and Gardar Drifts
AU: * Elmore, A C
EM: aelmore@rci.rutgers.edu
AF: Geology Department, Rutgers University, 610 Taylor Rd., Piscataway, NJ 08854, United States
AU: Wright, J D
EM: jdwright@rci.rutgers.edu
AF: Geology Department, Rutgers University, 610 Taylor Rd., Piscataway, NJ 08854, United States
AU: Neitzke, L C
EM: lneitzke@rci.rutgers.edu
AF: Geology Department, Rutgers University, 610 Taylor Rd., Piscataway, NJ 08854, United States
AU: Henderson, S
EM: samhend@rci.rutgers.edu
AF: Geology Department, Rutgers University, 610 Taylor Rd., Piscataway, NJ 08854, United States
AB: Northern Component Water (NCW; analogous to modern NADW) circulation has been described as bi-modal with shallow flow associated with the last glacial maximum (LGM) and a deeper current associated with the Holocene. We have generated foraminiferal stable isotope records as well as grain size records from cores collected on the Eirik and southern Gardar Drifts. Our records show that the shallow mode of NCW circulation persisted through the deglacial and into the early Holocene. Beginning around 9 ka (calendar age), the core of NCW began to descend, reaching its present position by 8 ka. This is consistent with Fagel et al. (2002) who argued that Denmark Strait overflow, which is the densest contributor to NCW, began around 8.5 ka. We note also that benthic foraminiferal oxygen isotope data from Gardar diverged from the Eirik data during the late deglacial and early Holocene, and may indicate the resumption of flow over the Iceland-Faroe Ridge and/or through the Faroe Bank Channel. Higher frequency changes in the benthic foraminiferal carbon isotopes during the late glacial through deglacial record interruptions in NCW flow. A 1 per mil decrease occurred from 18 to 16 ka. This decrease was associated with a 4-fold decrease in sedimentation rates and is interpreted as a further shoaling of NCW and influx of AABW. The start of this decrease predates the H1 event but the carbon isotope decrease continued through the H1 event, reaching minimum values at 16.3 ka. Between 16.3 and 14.0 ka, carbon isotope values fluctuated between 0 and 0.75 per mil. Sedimentation rates increased sharply to rates >25 cm/kyr, indicating that the current was actively supplying sediments with minimal winnowing. At 14 ka, carbon isotope values increased to ~1 per mil, associated with the Bolling-Allerod warming, and fluctuated about a mean of 1 per mil until the beginning of the Younger Dryas at 12.5ka. During the Younger Dryas, benthic carbon isotope values decreased by 0.5 per mil, signaling a minor reduction in NCW flux.
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4924 Geochemical tracers
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting