Neodymium isotopes as a paleo-water mass tracer: A model-data reassessment

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License: CC BY 4.0
Serval ID
serval:BIB_843B332ADA74
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Neodymium isotopes as a paleo-water mass tracer: A model-data reassessment
Journal
Quaternary Science Reviews
Author(s)
Pöppelmeier Frerk, Lippold Jörg, Blaser Patrick, Gutjahr Marcus, Frank Martin, Stocker Thomas F.
ISSN
0277-3791
Publication state
Published
Issued date
03/2022
Peer-reviewed
Oui
Volume
279
Pages
107404
Language
english
Abstract
Proxy reconstructions from deep ocean sediments have helped to shape our understanding of the role of the global overturning circulation in past climate change. Neodymium (Nd) isotopes have contributed to this knowledge, as a tracer of past bottom water provenance and mixing. Here, we extend the implementation of Nd isotopes in the physical-biogeochemical Bern3D model by revising a number of critical parameterizations, which result in an improved description of the marine Nd cycle. We exploit the dynamically consistent framework of the model, which allows us to assess the processes driving non-conservative Nd isotope behavior with a particular focus on the Last Glacial Maximum (LGM) and its substantially different climatic, oceanic, and biogeochemical boundary conditions. We show that the more radiogenic Nd isotopic compositions found throughout the glacial ocean can be explained by changes in the weathering input fluxes and do not require large reorganizations of the deep circulation. Our findings further highlight that the Nd isotopic composition of a water mass can not only be significantly affected by a benthic Nd flux, but also be modified by the vertical downward transport of Nd via reversible scavenging. While these non-conservative processes only have a limited impact in the modern ocean, they were substantially more pronounced during the LGM and mostly independent of the circulation state, with their contributions being non-linear, partially opposing, and spatially variable. During the transiently simulated deglaciation Nd isotope variations induced by major circulation weakenings and resumptions are found to be most pronounced in the South Atlantic, while they are increasingly muted towards the north. Hence, it emerges that the interpretation of authigenic Nd isotope records requires more spatially specific considerations of non-conservative processes in order to more reliably infer basin-scale ocean circulation and water mass mixing of the past.
Keywords
Geology, Archeology, Archeology, Ecology, Evolution, Behavior and Systematics, Global and Planetary Change
Web of science
Open Access
Yes
Funding(s)
Swiss National Science Foundation
Create date
04/11/2022 15:42
Last modification date
13/11/2022 7:11
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