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| Bayon, Germain; Loncke, L.; Dupre, Stephanie; Caprais, Jean-claude; Ducassou, E.; Duperron, Sebastien; Etoubleau, Joel; Foucher, Jean-paul; Fouquet, Yves; Gontharet, S.; Henderson, G. M.; Huguen, Caroline; Klaucke, I.; Mascle, J.; Migeon, S.; Olu-le-roy, Karine; Ondreas, Helene; Pierre, C.; Sibuet, Myriam; Stadnitskaia, A.; Woodside, J.. |
| We report on a multidisciplinary study of cold seeps explored in the Central Nile deep-sea fan of the Egyptian margin. Our approach combines in situ seafloor observation, geophysics, sedimentological data, measurement of bottom-water methane anomalies, pore-water and sediment geochemistry, and Th-230/U dating of authigenic carbonates. Two areas were investigated, which correspond to different sedimentary provinces. The lower slope, at similar to 2100 m water depth, indicates deformation of sediments by gravitational processes, exhibiting slope-parallel elongated ridges and seafloor depressions. In contrast, the middle slope, at similar to 1650 m water depth, exhibits a series of debris-flow deposits not remobilized by post-depositional gravity processes.... |
| Tipo: Text |
Palavras-chave: Authigenic carbonate; U Th; Cold seep; Continental margin; Nile. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6586.pdf |
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| Bayon, Germain; Henderson, G. M.; Bohn, Marcel. |
| On continental margins, oxidation of methane-rich fluids from the sediment often leads to formation of authigenic carbonate pavements on the seafloor. The biogeochemical processes involved during this carbonate precipitation are increasingly understood, but little is known about the duration or mode of carbonate crust formation. Here, we report uranium and thorium concentrations and isotope compositions for a set of 14 samples drilled across an authigenic carbonate pavement, which provide the first stratigraphy for a cold-seep carbonate crust. The 5.5-cm thick crust (NL7-CC2) was collected by Submersible on the Nile deep-sea fan in an area of active fluid venting. U-Th analyses must be corrected for initial Th and measurement of co-existing sediments... |
| Tipo: Text |
Palavras-chave: Nile fan; Cold seeps; Authigenic carbonates; U series. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6450.pdf |
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| Oliver, K. I. C.; Hoogakker, B. A. A.; Crowhurst, S.; Henderson, G. M.; Rickaby, R. E. M.; Edwards, N.r.; Elderfield, H.. |
| The isotopic composition of carbon, delta C-13, in seawater is used in reconstructions of ocean circulation, marine productivity, air-sea gas exchange, and biosphere carbon storage. Here, a synthesis of delta C-13 measurements taken from foraminifera in marine sediment cores over the last 150 000 years is presented. The dataset comprises previously published and unpublished data from benthic and planktonic records throughout the global ocean. Data are placed on a common delta O-18 age scale suitable for examining orbital timescale variability but not millennial events, which are removed by a 10 ka filter. Error estimates account for the resolution and scatter of the original data, and uncertainty in the relationship between delta C-13 of calcite and of... |
| Tipo: Text |
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| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00231/34258/32632.pdf |
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