| Registro completo |
| Provedor de dados: |
ArchiMer
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| País: |
France
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| Título: |
Diagenetic modulation of the magnetic properties in sediments from the Northern Indian Ocean
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| Autores: |
Bouilloux, Alexandra
Valet, Jean-pierre
Bassinot, Franck
Joron, Jean-louis
Blanc-valleron, Marie-madeleine
Moreno, Eva
Dewilde, Fabien
Kars, Myriam
Lagroix, France
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| Data: |
2013-09
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| Ano: |
2013
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| Palavras-chave: |
Paleomagnetism
Paleoenvironment
Goethite
Magnetite
Indian ocean
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| Resumo: |
Large changes in magnetic mineral concentration dependent parameters by more than 1 order of magnitude occur over 50-150 cm intervals in two marine sediment cores from the oxygen minimum zone in the Gulf of Aden. High-resolution sedimentological and chemical analyses indicate that these intervals are not associated with turbiditic events or sediment reworking, they do not result from changes in carbonate dilution or differences in sediment properties, and they do not correspond to volcanic layers. Magnetic mineralogical analyses reveal a change in magnetic mineral concentration from a magnetite-goethite assemblage to pure magnetite within the peak. The peaks almost disappear when the abundance of magnetic minerals is calculated after correcting for the magnetic moments of each magnetic mineral. Therefore, under the assumption that the variability of the magnetic parameters results from postdepositional mineralogical transformations, a relatively constant amount of magnetite was present at the surface of the sediment. Changes in redox conditions and nonsteady state diagenesis transformations have effectively been observed along both cores. Large values of total organic carbon coincide with poor preservation of biogenic and detrital magnetite, which reflects reductive dissolution of the finer magnetite grains. At the same levels, Fe2+ release from reductively dissolved magnetite favored precipitation of goethite. The susceptibility peaks coincide with episodes of magnetite preservation caused by reduced surface productivity and/or enhanced bottom-water ventilation accompanying northward extension of Glacial Antarctic Intermediate Water into the Indian Ocean.
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| Tipo: |
Text
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| Idioma: |
Inglês
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| Identificador: |
https://archimer.ifremer.fr/doc/00264/37488/36828.pdf
https://archimer.ifremer.fr/doc/00264/37488/36829.pdf
DOI:10.1002/ggge.20234
https://archimer.ifremer.fr/doc/00264/37488/
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| Editor: |
Amer Geophysical Union
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| Formato: |
application/pdf
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| Fonte: |
Geochemistry Geophysics Geosystems (1525-2027) (Amer Geophysical Union), 2013-09 , Vol. 14 , N. 9 , P. 3779-3800
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| Direitos: |
2013. American Geophysical Union. All Rights Reserved.
info:eu-repo/semantics/openAccess
restricted use
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