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Dynamic intermediate ocean circulation in the North Atlantic during Heinrich Stadial 1: a radiocarbon and neodymium isotope perspective

Wilson, David J. and Crocket, Kirsty C. and van de Flierdt, Tina and Robinson, Laura F. and Adkins, Jess F. (2014) Dynamic intermediate ocean circulation in the North Atlantic during Heinrich Stadial 1: a radiocarbon and neodymium isotope perspective. Paleoceanography, 29 (11). pp. 1072-1093. ISSN 0883-8305.

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The last deglaciation was characterised by a series of millennial scale climate events that have been linked to deep ocean variability. While often implied in interpretations, few direct constraints exist on circulation changes at mid-depths. Here we provide new constraints on the variability of deglacial mid-depth circulation using combined radiocarbon and neodymium isotopes in 24 North Atlantic deep-sea corals. Their aragonite skeletons have been dated by uranium-series, providing absolute ages and the resolution to record centennial scale changes, while transects spanning the lifetime of a single coral allow sub-centennial tracer reconstruction. Our results reveal that rapid fluctuations of water mass sourcing and radiocarbon affected the mid-depth water column (1.7-2.5 km) on timescales of less than 100 years during the latter half of Heinrich Stadial 1. The neodymium isotopic variability (−14.5 to −11.0) ranges from the composition of the modern northern-sourced waters towards more radiogenic compositions that suggest the presence of a greater southern-sourced component at some times. However, in detail, simple two-component mixing between well-ventilated northern-sourced and radiocarbon-depleted southern-sourced water masses cannot explain all our data. Instead, corals from ~15.0 ka and ~15.8 ka may record variability between southern-sourced intermediate waters and radiocarbon-depleted northern-sourced waters, unless there was a major shift in the neodymium isotopic composition of the northern endmember. In order to explain the rapid shift towards the most depleted radiocarbon values at ~15.4 ka, we suggest a different mixing scenario involving either radiocarbon-depleted deep water from the Greenland-Iceland-Norwegian Seas or a southern-sourced deep water mass. Since these mid-depth changes preceded the Bolling-Allerod warming, and were apparently unaccompanied by changes in the deep Atlantic, they may indicate an important role for the intermediate ocean in the early deglacial climate evolution.

Item Type:Article
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URLURL TypeDescription Information
Adkins, Jess F.0000-0002-3174-5190
Additional Information:© 2014 American Geophysical Union. Received 20 MAY 2014; Accepted 16 SEP 2014; Accepted article online 18 SEP 2014; Published online 20 NOV 2014. Data to support this article are provided in Table 1 and Table S1 of the Supporting Information. This study was supported by Natural Environment Research Council grant NE/F016751/1, Marie Curie International Reintegration Grant IRG 230828 and Leverhulme Trust grant RPG-398 to TvdF, as well as a Phillip Leverhulme Prize, Marie Curie International Reintegration Grant and European Research Council grant to LFR. We are grateful for thoughtful reviews from Marcus Gutjahr and an anonymous reviewer and the editorial handling by Heiko Pälike.
Funding AgencyGrant Number
Natural Environment Research Council (NERC)NE/F016751/1
Marie Curie International Reintegration GrantIRG 230828
Leverhulme TrustRPG-398
Phillip Leverhulme PrizeUNSPECIFIED
European Research Council (European Union)UNSPECIFIED
Subject Keywords:Heinrich stadial; deglaciation; Atlantic meridional overturning circulation; neodymium isotopes; radiocarbon; deep-sea corals
Issue or Number:11
Record Number:CaltechAUTHORS:20141027-140022061
Persistent URL:
Official Citation:Wilson, D. J., K. C. Crocket, T. van de Flierdt, L. F. Robinson, and J. F. Adkins (2014), Dynamic intermediate ocean circulation in the North Atlantic during Heinrich Stadial 1: A radiocarbon and neodymium isotope perspective, Paleoceanography, 29, pages 1072–1093. doi:10.1002/2014PA002674
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50872
Deposited By: Ruth Sustaita
Deposited On:27 Oct 2014 21:19
Last Modified:24 Feb 2020 10:30

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