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The large-scale evolution of neodymium isotopic composition in the global modern and Holocene ocean revealed from seawater and archive data

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Title: The large-scale evolution of neodymium isotopic composition in the global modern and Holocene ocean revealed from seawater and archive data
Authors: Tachikawa, K
Arsouze, T
Bayon, G
Bory, A
Colin, C
Dutay, J-C
Frank, N
Giraud, X
Gourlan, AT
Jeandel, C
Lacan, F
Meynadier, L
Montagna, P
Piotrowski, AM
Plancherel, Y
Puceat, E
Roy-Barman, M
Waelbroeck, C
Item Type: Journal Article
Abstract: Neodymium isotopic compositions (143Nd/144Nd or εNd) have been used as a tracer of water masses and lithogenic inputs to the ocean. To further evaluate the faithfulness of this tracer, we have updated a global seawater εNd database and combined it with hydrography parameters (temperature, salinity, nutrients and oxygen concentrations), carbon isotopic ratio and radiocarbon of dissolved inorganic carbon. Archive εNd data are also compiled for leachates, foraminiferal tests, deep-sea corals and fish teeth/debris from the Holocene period (< 10,000 years). At water depths ≥ 1500 m, property-property plots show clear correlations between seawater εNd and the other variables, suggesting that large-scale water mass mixing is a primary control of deepwater εNd distribution. At ≥ 200 m, basin-scale seawater T-S-εNd diagrams demonstrate the isotopic evolution of different water masses. Seawater and archive εNd values are compared using property-property plots and T-S-εNd diagrams. Archive values generally agree with corresponding seawater values although they tend to be at the upper limit in the Pacific. Both positive and negative offsets exist in the northern North Atlantic. Applying multiple regression analysis to deep (≥ 1500 m) seawater data, we established empirical equations that predict the main, large-scale, deepwater εNd trends from hydrography parameters. Large offsets from the predicted values are interpreted as a sign of significant local/regional influence. Dominant continental influence on seawater and archive εNd is observed mainly within 1000 km from the continents. Generally, seawater and archive εNd values form gradual latitudinal trend in the Atlantic and Pacific at depths ≥ 600 m, consistent with the idea that Nd isotopes help distinguish between northern/southern sourced water contributions at intermediate and deep water depths.
Issue Date: 10-May-2017
Date of Acceptance: 18-Mar-2017
URI: http://hdl.handle.net/10044/1/60859
DOI: https://dx.doi.org/10.1016/j.chemgeo.2017.03.018
ISSN: 0009-2541
Publisher: Elsevier
Start Page: 131
End Page: 148
Journal / Book Title: Chemical Geology
Volume: 457
Copyright Statement: © 2017 Elsevier B.V. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Keywords: Science & Technology
Physical Sciences
Geochemistry & Geophysics
Nd isotopes
Water mass tracer
Data compilation
Predicted seawater epsilon(Nd)
Seawater-archive comparison
RARE-EARTH-ELEMENTS
LAST GLACIAL MAXIMUM
NORTH-ATLANTIC DEEP
ANTARCTIC INTERMEDIATE WATER
MERIDIONAL OVERTURNING CIRCULATION
PARTICULATE MATERIAL DISSOLUTION
SEA SEDIMENTS IMPLICATIONS
MN OXYHYDROXIDE COATINGS
WESTERN PACIFIC-OCEAN
CENTRAL ARCTIC-OCEAN
0402 Geochemistry
0403 Geology
0406 Physical Geography And Environmental Geoscience
Publication Status: Published
Online Publication Date: 2017-03-21
Appears in Collections:Centre for Environmental Policy
Faculty of Natural Sciences



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