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Ocean circulation reconstructions from epsilon(Nd): A model-based feasibility study ArchiMer
Friedrich, T.; Timmermann, A.; Stichel, T.; Pahnke, K..
Over the past decade, records of the seawater neodymium isotopic composition (epsilon(Nd)) have become a widely used proxy to reconstruct changes in ocean circulation. Our study investigates the transient response of epsilon(Nd) to large-scale ocean circulation changes using an Earth system model of intermediate complexity. It is shown that a weakening of the North Atlantic Deep Water formation results in positive epsilon(Nd) anomalies in the Atlantic and the Pacific below 1000m water depth whereas variations in Antarctic Bottom Water production generate a Pacific-Atlantic dipole pattern of deep ocean epsilon(Nd) changes. Further experiments explore which ocean regions are suitable to record the temporal evolution of the overturning in the North Atlantic...
Tipo: Text Palavras-chave: Neodymium; Ocean circulation; Meridional overturning; Ocean modeling; Reconstruction.
Ano: 2014 URL: https://archimer.ifremer.fr/doc/00289/40055/39405.pdf
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Environmental Hf–Nd isotopic decoupling in World river clays ArchiMer
Bayon, Germain; Skonieczny, Charlotte; Delvigne, Camille; Toucanne, Samuel; Bermell, Sylvain; Ponzevera, Emmanuel; Andre, Luc.
The hafnium and neodymium radiogenic isotope systems behave differently during Earth surface processes, causing a wide dispersion of Hf and Nd isotopic compositions in sediments and other sedimentary rocks. The decoupling between Hf and Nd isotopes in sediments is generally attributed to a combination of preferential sorting of zircon during sediment transport and incongruent weathering processes on continents. In this study, we analysed size-fractions of sediment samples collected near the mouth of 53 rivers worldwide to better understand the factors controlling the distribution of Hf and Nd isotopes in sediments. Our results for rivers draining old cratonic areas and volcanic provinces demonstrate that both granite and basalt weathering can lead to...
Tipo: Text Palavras-chave: Hafnium isotopes; Neodymium; Rivers; Clays; Weathering; Climate.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00310/42094/41479.pdf
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Millennial-scale fluctuations of the European Ice Sheet at the end of the last glacial, and their potential impact on global climate ArchiMer
Toucanne, Samuel; Soulet, Guillaume; Freslon, Nicolas; Jacinto, Ricardo Silva; Dennielou, Bernard; Zaragosi, Sebastien; Eynaud, Frederique; Bourillet, Jean-francois; Bayon, Germain.
Reconstructing Northern Hemisphere ice-sheet oscillations and meltwater routing to the ocean is important to better understand the mechanisms behind abrupt climate changes. To date, research efforts have mainly focused on the North American (Laurentide) ice-sheets (LIS), leaving the potential role of the European Ice Sheet (EIS), and of the Scandinavian ice-sheet (SIS) in particular, largely unexplored. Using neodymium isotopes in detrital sediments deposited off the Channel River, we provide a continuous and well-dated record for the evolution of the EIS southern margin through the end of the last glacial period and during the deglaciation. Our results reveal that the evolution of EIS margins was accompanied with substantial ice recession (especially of...
Tipo: Text Palavras-chave: European ice-sheet; Channel River; Meltwater; Deglaciation; Neodymium; Termination.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00272/38346/36675.pdf
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Geochemical provenance of sediments from the northern East China Sea document a gradual migration of the Asian Monsoon belt over the past 400,000 years ArchiMer
Beny, Francois; Toucanne, Samuel; Skonieczny, Charlotte; Bayon, Germain; Ziegler, Martin.
The reconstruction of the long-term evolution of the East Asian Monsoon remains controversial. In this study, we aim to give a new outlook on this evolution by studying a 400 kyr long sediment record (U1429) from the northern East China Sea recovered during IODP Expedition 346. Neodymium isotopic ratios and rare earth element concentrations of different grain-size fractions reveal significant provenance changes of the sediments in the East China Sea between East Asian continental sources (mainly Yellow River) and sediment contributions from the Japanese Archipelago. These provenance changes are interpreted as the direct impact of sea level changes, due to the reorganization of East Asian river mouth locations and ocean circulation on the East China Sea...
Tipo: Text Palavras-chave: Monsoon; Eastern Asia; East China sea; Quaternary; Radiogenic isotopes; Neodymium; Rare earth elements.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00439/55088/56791.pdf
Registros recuperados: 4
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