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Sea-ice control on deglacial lower cell circulation changes recorded by Drake Passage deep-sea corals

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Title: Sea-ice control on deglacial lower cell circulation changes recorded by Drake Passage deep-sea corals
Authors: Wilson, DJ
Struve, T
Van de Flierdt, T
Chen, T
Li, T
Burke, A
Robinson, LF
Item Type: Journal Article
Abstract: The sequence of deep ocean circulation changes between the Last Glacial Maximum and the Holocene provides important insights for understanding deglacial climate change and the role of the deep ocean in the global carbon cycle. Although it is known that significant amounts of carbon were sequestered in a deep overturning cell during glacial periods and released during deglaciation, the driving mechanisms for these changes remain unresolved. Southern Ocean sea-ice has recently been proposed to play a critical role in setting the global deep ocean stratification and circulation, and hence carbon storage, but testing such conceptual and modelling studies requires data constraining past circulation changes. To this end, we present the first deglacial dataset of neodymium (Nd) isotopes measured on absolute-dated deep-sea corals from modern Lower Circumpolar Deep Water depths in the Drake Passage. Our record demonstrates deglacial variability of 2.5 εNd units, with radiogenic values of up to εNd = -5.9 during the Last Glacial Maximum providing evidence for a stratified glacial circulation mode with restricted incorporation of Nd from North Atlantic Deep Water in the lower cell. During the deglaciation, a renewed Atlantic influence in the deep Southern Ocean is recorded early in Heinrich Stadial 1, coincident with Antarctic sea-ice retreat, and is followed by a brief return to more Pacific-like values during the Antarctic Cold Reversal. These changes demonstrate a strong influence of Southern Ocean processes in setting deep ocean circulation and support the proposed sea-ice control on deep ocean structure. Furthermore, by constraining the Nd isotopic composition of Lower Circumpolar Deep Water in the Southern Ocean, our new data is important for interpreting deglacial circulation changes in other ocean basins and supports a spatially asynchronous return of North Atlantic Deep Water to the deep southeast and southwest Atlantic Ocean.
Issue Date: 15-Aug-2020
Date of Acceptance: 5-Jun-2020
URI: http://hdl.handle.net/10044/1/79644
DOI: 10.1016/j.epsl.2020.116405
ISSN: 0012-821X
Publisher: Elsevier
Start Page: 1
End Page: 10
Journal / Book Title: Earth and Planetary Science Letters
Volume: 544
Copyright Statement: © 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor/Funder: Natural Environment Research Council (NERC)
Commission of the European Communities
The Leverhulme Trust
Natural Environment Research Council (NERC)
Funder's Grant Number: NE/F016751/1
Keywords: Geochemistry & Geophysics
02 Physical Sciences
04 Earth Sciences
Publication Status: Published
Embargo Date: 2021-06-17
Online Publication Date: 2020-06-17
Appears in Collections:Faculty of Engineering
Earth Science and Engineering
Grantham Institute for Climate Change