HR: 0800h
AN: PP51B-0482    [Abstracts]
TI: Age differences between Atlantic and Pacific benthic d18O change at terminations
AU: * Lisiecki, L E
EM: lisiecki@bu.edu
AF: Boston University, 675 Commonwealth Ave, Boston, MA 02215,
AU: Raymo, M E
EM: raymo@bu.edu
AF: Boston University, 675 Commonwealth Ave, Boston, MA 02215,
AB: Because a large fraction of benthic δ¹⁸O change is due to global ice volume change, benthic δ¹⁸O is often used as stratigraphic tool to place marine records on a common age model and as a proxy for the timing of ice volume/sea level change. These applications require the assumptions that δ¹⁸O change is rapidly transmitted throughout the deep ocean and that the effects of hydrographic changes are in phase with ice volume. Recently, Skinner and Shackleton [2005] found that the timing of benthic δ¹⁸O change at the last termination differed by 4500 years between two sites in the Atlantic and Pacific. Based on Mg/Ca paleothermometry, they argued that these age discrepancies resulted from a late temperature increase in the Pacific and millennial-scale circulation changes in the Atlantic. Do these results imply that benthic δ¹⁸O change may not accurately record the timing of terminations? We compare benthic δ¹⁸O records from 34 sites in the Atlantic and Pacific to evaluate the impact of ocean mixing rates and deep water changes on the relative timing of terminations recorded in benthic δ¹⁸O. Statistical analysis of sedimentation rates derived from the alignment of benthic δ¹⁸O suggests an Atlantic lead over Pacific benthic δ¹⁸O change for all terminations of the last 600 kyr. The magnitude of sedimentation rate change suggests an average termination age difference of 1000-1500 years between the Atlantic and Pacific, consistent with or slightly greater than the delay expected due to ocean mixing rates, given that most glacial meltwater probably enters the North Atlantic.
DE: 4870 Stable isotopes (0454, 1041)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4946 Milankovitch theory
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting