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PALEOCEANOGRAPHY, VOL. 17, NO. 4, 1068, doi:10.1029/2002PA000782, 2002

Surface and deep ocean circulation in the subpolar North Atlantic during the mid-Pleistocene revolution

Amy K. Wright

College of Marine Science, University of South Florida, Florida, USA


Benjamin P. Flower

College of Marine Science, University of South Florida, Florida, USA


Abstract

We investigated surface and deep ocean variability in the subpolar North Atlantic from 1000 to 500 thousand years ago (ka) based on two Ocean Drilling Program (ODP) sites, Feni drift site 980 (55°29′N, 14°42′W) and Bjorn drift site 984 (61°25′N, 24°04′W). Benthic foraminiferal stable isotope data, planktic foraminiferal faunas, ice-rafted debris data, and faunally based sea-surface temperature estimates help test the hypothesis that oceanographic changes in the North Atlantic region were associated with the onset of the 100-kyr world during the mid-Pleistocene revolution. Based on percentage of Neogloboquadrina pachyderma (s) records from both sites, surface waters during interglacials and glacials were cooler in the mid-Pleistocene than during marine isotope stages (MIS) 5 and 6. In particular, interglaciations at Bjorn drift site 984 were significantly cooler. Faunal evidence suggests that the interglacial Arctic front shifted from a position between the two sites to a position northwest of Bjorn drift site 984 after ca. 610 ka. As during the late Pleistocene, we find faunal evidence for lagging surface warmth at most of the glacial initiations during the mid-Pleistocene. Each initiation is associated with high benthic δ13C values that are maintained into the succeeding glaciation, which we term “lagging NADW production.” These findings indicate that lagging warmth and lagging NADW production are robust features of the regional climate system that persist in the middle to late Pleistocene.

Published 18 December 2002.

Index Terms: 4267 Oceanography: General: Paleoceanography; 3030 Marine Geology and Geophysics: Micropaleontology; 9325 Information Related to Geographic Region: Atlantic Ocean; 4870 Oceanography: Biological and Chemical: Stable isotopes.

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Citation: Wright, A. K., and B. P. Flower (2002), Surface and deep ocean circulation in the subpolar North Atlantic during the mid-Pleistocene revolution, Paleoceanography, 17(4), 1068, doi:10.1029/2002PA000782.