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Abrupt response of chemical weathering to Late Quaternary hydroclimate changes in northeast Africa ArchiMer
Bastian, Luc; Revel, Marie; Bayon, Germain; Dufour, Aurelie; Vigier, Nathalie.
Chemical weathering of silicate rocks on continents acts as a major sink for atmospheric carbon dioxide and has played an important role in the evolution of the Earth’s climate. However, the magnitude and the nature of the links between weathering and climate are still under debate. In particular, the timescale over which chemical weathering may respond to climate change is yet to be constrained at the continental scale. Here we reconstruct the relationships between rainfall and chemical weathering in northeast Africa for the last 32,000 years. Using lithium isotopes and other geochemical proxies in the clay-size fraction of a marine sediment core from the Eastern Mediterranean Sea, we show that chemical weathering in the Nile Basin fluctuated in parallel...
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Ano: 2017 URL: https://archimer.ifremer.fr/doc/00376/48697/49030.pdf
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The control of weathering processes on riverine and seawater hafnium isotope ratios ArchiMer
Bayon, Germain; Vigier, Nathalie; Burton, Kevin W.; Brenot, Agnès; Carignan, Jean; Etoubleau, Joel; Chu, Nan-chin.
Hafnium Hf-176/Hf-177 isotope ratio variations in marine records are thought to reflect changes in continental weathering through time, but the behavior of Hf in rivers, and during weathering, is not well understood. Here, we present Hf-176/Hf-177 data for rivers, bedrock, soils, and leaching experiments for the Moselle basin, Vosges, France. These data strongly suggest that the Hf-176/Hf-177 composition of river waters is controlled by preferential dissolution of accessory phases (i.e., apatite, sphene) versus more resistant minerals (e.g., K-feldspar) and linked to the intensity of silicate weathering. Estimates for the global isotopic composition of riverine Hf suggest that the ocean Hf budget may be dominated by river input, and variations seen in...
Tipo: Text Palavras-chave: Ocean chemistry; Silicate weathering; Rivers; Hafnium isotopes.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-2078.pdf
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