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| Titel |
Do foraminifera accurately record seawater neodymium isotope composition? |
| VerfasserIn |
Adam Scrivner, Luke Skinner, Derek Vance |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035768
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| Zusammenfassung |
| Palaeoclimate studies involving the reconstruction of past Atlantic meridional overturning circulation increasingly employ isotopes of neodymium (Nd), measured on a variety of sample media (Frank, 2002). In the open ocean, Nd isotopes are a conservative tracer of water mass mixing and are unaffected by biological and low-temperature fractionation processes (Piepgras and Wasserburg, 1987; Lacan and Jeandel, 2005). For decades, benthic foraminifera have been widely utilised in stable isotope and geochemical studies, but have only recently begun to be exploited as a widely distributed, high-resolution Nd isotope archive (Klevenz et al., 2008), potentially circumventing the difficulties associated with other methods used to recover past deep-water Nd isotopes (Klevenz et al., 2008; Rutberg et al., 2000; Tachikawa et al., 2004). Thus far, a single pilot study (Klevenz et al., 2008) has indicated that core-top sedimentary benthic foraminifera record a Nd isotope composition in agreement with the nearest available bottom seawater data, and has suggested that this archive is potentially useful on both millennial and million-year timescales.
Here we present seawater and proximal core-top foraminifer Nd isotope data for samples recovered during the 2008 “RETRO” cruise of the Marion Dufresne. The foraminifer samples comprise a depth-transect spanning 3000m of the water column in the Angola Basin and permit a direct comparison between high-resolution water column and core-top foraminiferal Nd isotope data. We use these data to assess the reliability of both planktonic and benthic foraminifera as recorders of water column neodymium isotope composition.
Frank, M., 2002. Radiogenic isotopes: Tracers of past ocean circulation and erosional input, Rev. Geophys., 40 (1), 1001, doi:10.1029/2000RG000094.
Klevenz, V., Vance, D., Schmidt, D.N., and Mezger, K., 2008. Neodymium isotopes in benthic foraminifera: Core-top systematics and a down-core record from the Neogene south Atlantic, Earth Planet. Sci. Lett. 265, 571-587.
Lacan, F., and Jeandel, C., 2005a. Neodymium isotopes as a new tool for quantifying exchange fluxes at the continent–ocean interface, Earth Planet. Sci. Lett. 232, 245-257.
Piepgras, D.J., and Wasserburg, G.J., 1987. Rare earth element transport in the western North Atlantic inferred from Nd isotopic observations. Geochim. Cosmochim. Acta 51, 1257-1271.
Rutberg, R.L., Hemming, S.R., and Goldstein, S.L., 2000. Reduced North Atlantic deep water flux to the glacial southern ocean inferred from neodymium isotope ratios. Nature 405, 935–938.
Tachikawa, K., Roy-Barman, M., Michard, A., Thouron, D., Yeghicheyan, D., and Jeandel, C., 2004. Neodymium isotopes in the Mediterranean Sea: comparison between seawater and sediment signals. Geochim. Cosmochim. Acta 68, 3095-3106. |
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