Surface and Deep Ocean Circulation in the Subpolar North Atlantic During the Mid-Pleistocene Revolution

• Published in: Paleoceanography
• Main Authors: Wright, Amy K., Flower, Benjamin P.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Digital Commons @ University of South Florida 2002
• Subjects: paleoceanography; foraminifera; stable isotopes; north Atlantic; mid-Pleistocene Ocean Drilling Program; leg 162; Life Sciences; Marine Biology; Foraminifera*; NADW; Neogloboquadrina pachyderma; North Atlantic
• Online Access: https://digitalcommons.usf.edu/msc_facpub/23; https://doi.org/10.1029/2002PA000782; https://digitalcommons.usf.edu/context/msc_facpub/article/1022/viewcontent/Wright_et_al_2002_Paleoceanography.pdf

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, iceâ€rafted debris data, and faunally based seaâ€surface temperature estimates help test the hypothesis that oceanographic changes in the North Atlantic region were associated with the onset of the 100â€kyr world during the midâ€Pleistocene revolution. Based on percentage of Neogloboquadrina pachyderma (s) records from both sites, surface waters during interglacials and glacials were cooler in the midâ€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 midâ€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.