Neodymium isotope constraints on provenance, dispersal, and climate-driven supply of Zambezi sediments along the Mozambique Margin during the past similar to 45,000 years
van der Lubbe, H.J.L.; Frank, M.; Tjallingii, R.; Schneider, R. (2016). Neodymium isotope constraints on provenance, dispersal, and climate-driven supply of Zambezi sediments along the Mozambique Margin during the past similar to 45,000 years. Geochem. Geophys. Geosyst. 17(1): 181-198. dx.doi.org/10.1002/2015GC006080
In: Geochemistry, Geophysics, Geosystems. American Geophysical Union: Washington, DC. ISSN 1525-2027; e-ISSN 1525-2027, meer
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| Auteurs | | Top |
- van der Lubbe, H.J.L.
- Frank, M.
- Tjallingii, R., meer
- Schneider, R.
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| Abstract |
Marine sediments deposited off the Zambezi River that drains a considerable part of the south-east African continent provide continuous records of the continental climatic and environmental conditions.Here we present time series of neodymium (Nd) isotope signatures of the detrital sediment fraction duringthe past ?45,000 years, to reconstruct climate-driven changes in the provenance of clays deposited alongthe Mozambique Margin. Coherent with the surface current regime, the Nd isotope distribution in surfacesediments reveals mixing of the alongshore ?owing Zambezi suspension load with sediments supplied bysmaller rivers located further north. To reconstruct past changes in sediment provenances, Nd isotope sig-natures of clays that are not signi?cantly fractionated during weathering processes have been obtainedfrom core 64PE304-80, which was recovered just north of the Zambezi mouth at 1329 m water depth. Dis-tinctly unradiogenic clay signatures ( ENdvalues <214.2) are found during the Last Glacial Maximum, Hein-rich Stadial 1, and Younger Dryas. In contrast, the Nd isotope record shows higher, more radiogenic isotopesignatures during Marine Isotope Stage 3 and between ?15 and ?5 ka BP, the latter coinciding with thetiming of the northern hemisphere African Humid Period. The clay-sized sediment fraction with the leastradiogenic Nd isotope signatures was deposited during the Holocene, when the adjacent MozambiqueShelf became completely ?ooded. In general, the contribution of the distinctly unradiogenic Zambezi sus-pension load has followed the intensity of precession-forced monsoonal precipitation and enhanced duringperiods of increased southern hemisphere insolation and high-latitude northern hemispheric climatevariability |
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