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| Registros recuperados: 78 | |
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| Tallobre, Cédric; Giresse, Pierre; Bassetti, Maria-angela; Loncke, Lies; Bayon, Germain; Buscail, Roselyne; Tudryn, Alina; Zaragosi, Sébastien. |
| The Demerara Plateau is a marginal plateau which forms a bathymetric relief on the sea floor. Here, contourite deposits have been studied in detail, following the recent discovery of contourite sequences likely related to the bottom currents and linked both to contour current and peculiar sea-floor morphology. A chronostratigraphic framework, based on δ18O relative variations and palaeomagnetic events in sediment cores allows correlating sediment processes to current intensity changes and major climate phases (glacial or interglacial). The studied sediments are enriched in glauconitic grains. In addition, the glauconite mineralogical maturity can easily correlate to low sedimentation rate and slightly energetic bottom currents on the seafloor. Based on... |
| Tipo: Text |
Palavras-chave: Marginal plateau; Contourite; Glauconite; Demerara plateau. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00485/59665/62724.pdf |
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| Wang, X.; Barrat, Jean-alix; Bayon, Germain; Chauvaud, Laurent; Feng, D.. |
| Methane is an important greenhouse gas whose emissions into the oceans and atmosphere are regulated by relatively unconstrained anaerobic and aerobic microbial processes. The aerobic pathway for methane oxidation is thought to be largely dependent upon the use of rare earth elements (REE), but to date the effects of this process on their abundances in bacteria or in organisms living in symbiosis with methanotrophs remain to be evaluated. Here we show that deep sea chemosynthetic mussels prospering at methane seeps display distinctive lanthanum enrichments linked to the enzymatic activities of their symbionts. These results demonstrate that methanotrophy is able to fractionate efficiently REE distributions in organisms and possibly in the environment.... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00643/75532/76427.pdf |
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| Pierre, Catherine; Bayon, Germain; Blanc-valleron, Marie-madeleine; Mascle, Jean; Dupre, Stephanie. |
| On the passive margin of the Nile deep-sea fan, the active Cheops mud volcano (MV; ca. 1,500 m diameter, ~20–30 m above seafloor, 3,010–3,020 m water depth) comprises a crater lake with hot (up to ca. 42 °C) methane-rich muddy brines in places overflowing down the MV flanks. During the Medeco2 cruise in fall 2007, ROV dives enabled detailed sampling of the brine fluid, bottom lake sediments at ca. 450 m lake depth, sub-surface sediments from the MV flanks, and carbonate crusts at the MV foot. Based on mineralogical, elemental and stable isotope analyses, this study aims at exploring the origin of the brine fluid and the key biogeochemical processes controlling the formation of these deep-sea authigenic carbonates. In addition to their patchy occurrence in... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00186/29735/28189.pdf |
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| 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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| Bayon, Germain; Burton, K. W.; Soulet, Guillaume; Vigier, N.; Dennielou, Bernard; Etoubleau, Joel; Ponzevera, Emmanuel; German, C. R.; Nesbitt, R. W.. |
| The combined use of Lu-Hf and Sm-Nd isotope systems potentially offers a unique perspective for investigating continental erosion, but little is known about whether, and to what extent, the Hf-Nd isotope composition of sediments is related to silicate weathering intensity. In this study, Hf and Nd elemental and isotope data are reported for marine muds, leached Fe-oxide fractions and zircon-rich turbidite sands collected off the Congo River mouth, and from other parts of the SE Atlantic Ocean. All studied samples from the Congo fan (muds, Fe-hydroxides, sands) exhibit indistinguishable Nd isotopic composition (epsilon(Nd)similar to - 16), indicating that Fe-hydroxides leached from these sediments correspond to continental oxides precipitated within the... |
| Tipo: Text |
Palavras-chave: Congo fan; Seawater array; Continental erosion; Silicate weathering; Hafnium isotopes; Neodymium isotopes. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6451.pdf |
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| Yu, Zhaojie; Colin, Christophe; Bassinot, Franck; Wan, Shiming; Bayon, Germain. |
| Chemical weathering of silicate rocks on continents is thought to have played an important role in the evolution of past atmospheric carbon dioxide over geologic timescales. However, the detailed links between continental weathering and climate change over shorter timescales, and their potential impact on sediment records deposited in the ocean, remain poorly understood. Here, we present clay mineralogy and strontium‐neodymium isotopic data for marine sediment records from the Northern Indian Ocean, with the aim of investigating the weathering response of large Himalayan river basins to orbital and millennial climate forcing. We show that past glaciated episodes of the late Quaternary corresponded to periods of increased physical erosion, associated with... |
| Tipo: Text |
Palavras-chave: Climate change<; /AUTHOR_KEYWORD>; Continental weathering<; /AUTHOR_KEYWORD>; Highlands and floodplains<; /AUTHOR_KEYWORD>; Carbon cycle<; /AUTHOR_KEYWORD>; Himalaya<; /AUTHOR_KEYWORD>. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00632/74434/74154.pdf |
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| Cattaneo, Antonio; Badhani, Shray; Caradonna, Cristina; Bellucci, Massimo; Leroux, Estelle; Babonneau, Nathalie; Garziglia, Sebastien; Poort, Jeffrey; Akhmanov, Grigorii G.; Bayon, Germain; Dennielou, Bernard; Jouet, Gwenael; Migeon, Sebastien; Rabineau, Marina; Droz, Laurence; Clare, Michael. |
| Megabeds are thick sedimentary layers extending over thousands square kilometres in deep sea basins and are thought to result from large slope failures triggered by major external events. Such deposits have been found in at least three areas of the Mediterranean Sea. Although their discovery dates back to the early 1980s, many questions remain, concerning their initiation, source area, extent, and the nature of their emplacement. One of the largest previously documented megabeds was emplaced during the Last Glacial Maximum across the Balearic Abyssal Plain with a thickness of 8-10 m in water depths of up to 2800 m. New 3.5 kHz sub-bottom profiles and sediment cores provide greater constraint on the lateral variability of the megabed and allow to map it... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00614/72597/71595.pdf |
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| Bayon, Germain; German, Cr; Nesbitt, Rw; Bertrand, P; Schneider, Rr. |
| [1] Analysis of radiogenic isotopes in marine sediments can provide useful information on the provenance and transport of detrital material, directly relevant to paleoceanographic investigations. Here we show that the detrital Nd isotopic composition of recent SE Atlantic marine sediments matches the complex modern-day hydrography. In these same cores, glacial-interglacial isotopic variations are consistent with previous investigations (using different paleoceanographic proxies), which have shown that the relative influence of North Atlantic Deep Water (NADW) into the South Atlantic was reduced during glacial periods. In a novel departure, however, we also calculate the mass accumulation rates of terrigenous material delivered by each of Circumpolar Deep... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Detrital fractions; South Atlantic; Deep water circulation; IMAGES; Marine geology and geophysics : marine sediments processes and transport; Oceanography : general : paleoceanography. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00000/10190/9912.pdf |
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| Bayon, Germain; Pierre, C; Etoubleau, Joel; Voisset, Michel; Cauquil, E; Marsset, Tania; Sultan, Nabil; Le Drezen, Eliane; Fouquet, Yves. |
| We report on a reconnaissance analysis of the geochemical composition of authigenic carbonates and sediment samples collected from various seepage sites on the Niger deep-sea fan. Our aim has been to investigate whether evidence for the presence of authigenic carbonates and gas hydrates within sediments is discernible from solid-phase sediment geochemistry. We show that sedimentary Sr/Ca and Mg/Ca ratios can be used to infer the presence of authigenic aragonite (Sr-rich) and Mg-rich carbonate phases (high-Mg calcite, dolomite) in cold seep settings. Using Sr/Ca and Mg/Ca ratios, the proportion (wt.%) of authigenic carbonates in Niger Fan sediments can be calculated from a mixing model between sediment fractions of terrigenous material, biogenic calcite,... |
| Tipo: Text |
Palavras-chave: Niger Delta; Gas hydrates; Cold seeps; Mg/Ca; Sr/Ca; Authigenic carbonates. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2696.pdf |
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| Wan, Shiming; Toucanne, Samuel; Clift, Peter D.; Zhao, Debo; Bayon, Germain; Yu, Zhaojie; Cai, Guanqiang; Yin, Xuebo; Revillon, Sidonie; Wang, Dawei; Li, Anchun; Li, Tiegang. |
| During the Holocene there has been a gradual increase in the influence of humans on Earth systems. High-resolution sedimentary records can help us to assess how erosion and weathering have evolved in response to recent climatic and anthropogenic disturbances. Here we present data from a high-resolution (∼75 cm/k.y.) sedimentary archive from the South China Sea. Provenance data indicate that the sediment was derived from the Red River, and can be used to reconstruct the erosion and/or weathering history in this river basin. Accelerator mass spectrometry 14C dating provides direct age control and reveals coherent variations in clay mineralogy, geochemistry, and terrigenous flux, indicative of strong chemical weathering and physical erosion during the... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00266/37754/37175.pdf |
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| Toucanne, Samuel; Soulet, Guillaume; Freslon, Nicolas; Jacinto, Ricardo Silva; Dennielou, Bernard; Zaragosi, Sebastien; Eynaud, Frederique; Bourillet, Jean-francois; Bayon, Germain. |
| Reconstructing Northern Hemisphere ice-sheet oscillations and meltwater routing to the ocean is important to better understand the mechanisms behind abrupt climate changes. To date, research efforts have mainly focused on the North American (Laurentide) ice-sheets (LIS), leaving the potential role of the European Ice Sheet (EIS), and of the Scandinavian ice-sheet (SIS) in particular, largely unexplored. Using neodymium isotopes in detrital sediments deposited off the Channel River, we provide a continuous and well-dated record for the evolution of the EIS southern margin through the end of the last glacial period and during the deglaciation. Our results reveal that the evolution of EIS margins was accompanied with substantial ice recession (especially of... |
| Tipo: Text |
Palavras-chave: European ice-sheet; Channel River; Meltwater; Deglaciation; Neodymium; Termination. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00272/38346/36675.pdf |
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| Lericolais, Gilles; Bourget, Julien; Jorry, Stephan; Popescu, Irina; Abreu, Victor; Jouannic, Gwenael; Bayon, Germain. |
| The Danube River Basin and the Black Sea represent a unique natural laboratory for studying source to sink and global change. We will address information on the “active sink” of the system, which represents the area of active deposition: sea level variation, sediment balance, and neotectonics. Also, we will discuss the evolution and quantification of climate, tectonics, and eustasy on the sedimentation in the western Black Sea basin, along both southern and northern margins, obtained from understanding the Danube deep-sea fan processes and sedimentation. In the last decade, many of the geosciences studies carried out in the Black Sea have focused on the Holocene marine transgression. This topic has been fully discussed and is still a matter of debate.... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00316/42695/42273.pdf |
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| Fontanier, Christophe; Mamo, Briony; Toucanne, Samuel; Bayon, Germain; Schmidt, Sabine; Deflandre, Bruno; Dennielou, Bernard; Jouet, Gwenael; Garnier, Eline; Sakai, Saburo; Lamas, Ruth Martinez; Duros, Pauline; Toyofuku, Takashi; Sale, Aurelien; Belleney, Deborah; Bichon, Sabrina; Boissier, Audrey; Cheron, Sandrine; Pitel, Mathilde; Roubi, Angelique; Rovere, Mickael; Gremare, Antoine; Dupre, Stephanie; Jorry, Stephan. |
| In this short communication, we present a multidisciplinaty study of sedimentary records collected from a deep-sea interfluve proximal to the mouths of major northwestern Madagascan rivers. For the last 60 years, the seafloor has been repeatedly disturbed by the deposition of organic rich, tropical, terrestrial sediments causing marked reductions in benthic biodiversity. Increased soil erosion due to local land-use, deforestation and intensifying tropical cyclones are potential causes for this sedimentary budget and biodiversity shift. Our marine sedimentary records indicate that until now, these conditions have not occurred within the region for at least 20,000 years. |
| Tipo: Text |
Palavras-chave: Multidisciplinary study; Benthic foraminifera; Land-use; Tropical cyclones. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00413/52488/53276.pdf |
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| Tachikawa, Kazuyo; Arsouze, Thomas; Bayon, Germain; Bory, Aloys; Colin, Christophe; Dutay, Jean-claude; Frank, Norbert; Giraud, Xavier; Gourlan, Alexandra T.; Jeandel, Catherine; Lacan, Francois; Meynadier, Laure; Montagna, Paolo; Piotrowski, Alexander M.; Plancherel, Yves; Puceat, Emmanuelle; Roy-barman, Matthieu; Waelbroeck, Claire. |
| Neodymium isotopic compositions (143Nd/144Nd or εNd) have been used as a tracer of water masses and lithogenic inputs to the ocean. To further evaluate the faithfulness of this tracer, we have updated a global seawater εNd database and combined it with hydrography parameters (temperature, salinity, nutrients and oxygen concentrations), carbon isotopic ratio and radiocarbon of dissolved inorganic carbon. Archive εNd data are also compiled for leachates, foraminiferal tests, deep-sea corals and fish teeth/debris from the Holocene period (< 10,000 years). At water depths ≥ 1500 m, property-property plots show clear correlations between seawater εNd and the other variables, suggesting that large-scale water mass mixing is a primary control of deepwater εNd... |
| Tipo: Text |
Palavras-chave: Nd isotopes; Water mass tracer; Data compilation; Predicted seawater epsilon(Nd); Seawater-archive comparison. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00376/48768/49165.pdf |
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| Lemaitre, Nolwenn; Bayon, Germain; Ondreas, Helene; Caprais, Jean-claude; Freslon, Nicolas; Bollinger, Claire; Rouget, Marie-laure; De Prunele, Alexis; Ruffine, Livio; Olu-le Roy, Karine; Sarthou, Geraldine. |
| Seawater samples were collected by submersible above methane seeps in the Gulf of Guinea (Regab and Baboon pockmarks) in order to investigate the behaviour of iron (Fe), manganese (Mn) and rare earth elements (REE) during fluid seepage. Our aim was to determine whether cold seeps may represent potential sources of dissolved chemical species to the ocean. Dissolved (<0.45 μm filtered samples) and total dissolvable (unfiltered samples) concentrations were determined over ∼50 m long vertical transects above the seafloor and at various discrete locations within the pockmarks. We show that substantial amounts of Fe and Mn are released into seawater during seepage of methane-rich fluids. Mn is exported almost quantitatively in the dissolved form (more than... |
| Tipo: Text |
Palavras-chave: Iron; Rare earth elements; Cold seeps; Seawater; Organic ligands; Iron-sulfide nanoparticles. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00211/32190/30704.pdf |
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| Teichert, B. M. A.; Chevalier, N.; Gussone, N.; Bayon, Germain; Ponzevera, Emmanuel; Ruffine, Livio; Strauss, H.. |
| During the MARSITECruise expedition in November 2014 on board the RV Pourquoi Pas?, multidisciplinary sampling was carried out with the ROV Victor 6000 in order to investigate biogeochemical processes taking place at cold seep environments in the Sea of Marmara. Pore water, bottom water, sediment and authigenic carbonate samples were collected from two short push cores (MRS-DV5-PC04 − 8 cm, MRS-DV5-PC01 − 12.5 cm) at an active methane bubbling site in the southeastern part of the Çinarcik Basin. Sulfate sulfur and oxygen isotope data as well as sulfide isotope data indicate that sulfate-dependent anaerobic oxidation of methane is the dominant process in the sediments. This is confirmed by archaeal lipids diagnostic for anaerobic methane oxidizers detected... |
| Tipo: Text |
Palavras-chave: Sea of Marmara; Cinarcik Basin; Methane; Sulfate reduction; Anaerobic oxidation of methane; Authigenic carbonate; Lipid biomarker. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00413/52480/53267.pdf |
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| Registros recuperados: 78 | |
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