Neodymium isotopes and concentrations in Caribbean seawater: Tracing water mass mixing and continental input in a semi-enclosed ocean basin.

Osborne, Anne, Haley, Brian, Hathorne, Ed, Floegel, Sascha and Frank, Martin (2014) Neodymium isotopes and concentrations in Caribbean seawater: Tracing water mass mixing and continental input in a semi-enclosed ocean basin. Earth and Planetary Science Letters, 406 . pp. 174-186. DOI 10.1016/j.epsl.2014.09.011.

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Supplementary data:

Abstract

We present the first full water column Nd isotope (εNd) and concentration data for Caribbean seawater, as well as for stations close to the Orinoco River mouth and in the Florida Straits. The surface inflow into the southeastern Caribbean via the Guyana Current is characterized by an εNdsignature of −10.9, which is a consequence of the mixing of relatively unradiogenic εNdsignatures (−13.6) supplied by the Orinoco River with contributions from the Amazon River (∼−10). Despite the proximity to land, sub-surface and intermediate waters within the Caribbean largely retain the εNdsignatures of their source water masses in the Atlantic. In contrast, the deep waters of the Caribbean show εNdsignatures at least 3 εNdunits more radiogenic than the inflowing Upper North Atlantic Deep Water (UNADW). A εNdshift from −13 to −9.7 can be explained by addition of radiogenic Nd to the deep Caribbean through weathering inputs from land. However, in order to balance such large shifts in εNdwith at the same time modest increases in Nd concentrations, Nd must also be removed from seawater within the basin. It is suggested that the long residence time of deep waters in the Caribbean allows significant interaction of seawater with sinking particles and seafloor sediments resulting in more radiogenic values. These findings have implications for the use of εNdas a proxy for paleocirculation in restricted basins, in which the residence times of the deep waters are long.

Document Type: Article
Additional Information: WOS:000344211200018
Keywords: neodymium isotopes; Caribbean seawater; Amazon River; Orinoco River; Atlantic inflow; boundary exchange
Research affiliation: OceanRep > SFB 754 > A7
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > SFB 754
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2014.09.011
ISSN: 0012-821X
Projects: SFB754, Laptev Sea System, Transdrift, Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 21 Oct 2014 07:36
Last Modified: 08 Jun 2018 08:51
URI: http://oceanrep.geomar.de/id/eprint/25746

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