Evidence for stable Holocene basin-scale overturning circulation despite variable currents along the deep western boundary of the North Atlantic Ocean

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doi: 10.1029/2018GL080187
Author(s): Hoffmann, Sharon S.; McManus, Jerry F.; Swank, Emerson
Author Affiliation(s): Primary:
University of North Carolina at Wilmington, Department of Earth and Ocean Sciences, Wilmington, NC, United States
Columbia University, United States
Volume Title: Geophysical Research Letters
Source: Geophysical Research Letters, 45(24), p.13,427-13,436. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0094-8276 CODEN: GPRLAJ
Note: In English. 56 refs.; illus.
Summary: While substantial changes in thermohaline circulation related to deglacial climate variability are well established, the role of this circulation in Holocene climate variability remains uncertain. Here we use two dynamical proxies, 231Pa/230Th ratios and mean sortable silt size (SS), to reconstruct Holocene bottom water circulation at the intermediate-depth Carolina Slope. We find no substantial change in deep current speed or 231Pa export at this site during the Holocene, suggesting consistent 231Pa export via the Deep Western Boundary Current. SS shows increasing millennial-scale variability in the middle-late Holocene, which may reflect Labrador Sea Water contribution to current speed. We conclude that deepwater export from the North Atlantic has remained remarkably stable during the Holocene, decoupled from changing rates of specific water masses, while production of these water masses varied at millennial to centennial time scales. The persistence of the large-scale overturning may reflect the ocean's stabilizing influence on Holocene climate. Abstract Copyright (2018), American Geophysical Union. All Rights Reserved.
Year of Publication: 2018
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Actinides; Atlantic Ocean; Bottom currents; Burial; Carolina Slope; Cenozoic; Circulation; Climate change; Continental margin; Continental slope; Currents; Decoupling; Deep Western Boundary Current; Deglaciation; Grain size; Holocene; Isotopes; Leg 172; Metals; North Atlantic; ODP Site 1055; Ocean Drilling Program; Pa-231; Pa-231/Th-230; Protactinium; Quaternary; Radioactive isotopes; Reconstruction; Sediment supply; Sedimentation; Sedimentation rates; South Carolina; Th-230; Thermohaline circulation; Thorium; U-235; United States; Uranium
Coordinates: N324704 N324704 W0761711 W0761711
Record ID: 2019049888
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom