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Distribution of major elements in Atlantic surface sediments (36 degrees N-49 degrees S): Imprint of terrigenous input and continental weathering ArchiMer
Govin, Aline; Holzwarth, Ulrike; Heslop, David; Keeling, Lara Ford; Zabel, Matthias; Mulitza, Stefan; Collins, James A.; Chiessi, Cristiano M..
Numerous studies use major element concentrations measured on continental margin sediments to reconstruct terrestrial climate variations. The choice and interpretation of climate proxies however differ from site to site. Here we map the concentrations of major elements (Ca, Fe, Al, Si, Ti, K) in Atlantic surface sediments (36 degrees N-49 degrees S) to assess the factors influencing the geochemistry of Atlantic hemipelagic sediments and the potential of elemental ratios to reconstruct different terrestrial climate regimes. High concentrations of terrigenous elements and low Ca concentrations along the African and South American margins reflect the dominance of terrigenous input in these regions. Single element concentrations and elemental ratios including...
Tipo: Text Palavras-chave: Atlantic surface sediments; Terrigenous input; Major elements.
Ano: 2012 URL: https://archimer.ifremer.fr/doc/00214/32550/31035.pdf
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High-resolution carbonate stratigraphy of IMAGES core MD972151 from South China Sea ArchiMer
Huang, Cy; Wang, Cc; Zhao, Mx.
High-resolution carbonate stratigraphy of the deep-sea core MD972151 from the southwestern South China Sea shows millennial-scale variability similar to oxygen isotopic fluctuations recorded in ice cores from Greenland. In a long term of glacial-interglacial scale, carbonate contents in the interglacial time (up to 25 % by weight) were higher than that in the glacial periods (5-15 % by weight). Even for the last glacial, carbonate contents are relatively high in the interstadial events and low in the stadial horizons. This demonstrates clearly that carbonate content in the continental slope above the lysocline in the southwestern South China Sea is primarily controlled by dilution of terrigenous inputs, which in turn is due to sea-level fluctuations in...
Tipo: Text Palavras-chave: South China Sea; Carbonate stratigraphy; Ice volume; Terrigenous input.
Ano: 1999 URL: https://archimer.ifremer.fr/doc/00239/35073/34557.pdf
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Signatures and significance of aeolian, fluvial, bacterial and diagenetic magnetic mineral fractions in Late Quaternary marine sediments off Gambia, NW Africa ArchiMer
Just, Janna; Dekkers, Mark J.; Von Dobeneck, Tilo; Van Hoesel, Annelies; Bickert, Torsten.
Two gravity cores retrieved off NW Africa at the border of arid and subtropical environments (GeoB 13602-1 and GeoB 13601-4) were analyzed to extract records of Late Quaternary climate change and sediment export. We apply end-member (EM) unmixing to 350 acquisition curves of isothermal remanent magnetization (IRM). Our approach enables to discriminate rock magnetic signatures of aeolian and fluvial material, to determine biomineralization and reductive diagenesis. Based on the occurrence of pedogenically formed magnetic minerals in the fluvial and aeolian EMs, we can infer that goethite formed in favor to hematite in more humid climate zones. The diagenetic EM dominates in the lower parts of the cores and within a thin near-surface layer probably...
Tipo: Text Palavras-chave: IRM end-member modeling; NW Africa; Environmental magnetism; Magnetotactic bacteria; Paleoclimate; Terrigenous input.
Ano: 2012 URL: https://archimer.ifremer.fr/doc/00265/37617/36987.pdf
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