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| Registros recuperados: 32 | |
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| Bayon, Germain; Henderson, Gideon M.; Etoubleau, Joel; Caprais, Jean-claude; Ruffine, Livio; Marsset, Tania; Dennielou, Bernard; Cauquil, Eric; Voisset, Michel; Sultan, Nabil. |
| The application of uranium-thorium dating methods to authigenic carbonates provides unique constraints on the temporal evolution of methane seeps at ocean margins. In this study, we report U-Th isotope measurements for carbonate breccias collected from within a hydrate-bearing pockmark located at the Niger Delta margin. These concretions were extracted from a carbonate-rich layer in the upper two meters of a sediment core (N2-KS-44; ~ 1200 m water depth), well above the present-day sulphate-methane transition zone (about 3 m depth) and the presence of gas hydrates in the sediment. The stratigraphy of core N2-KS-44 was established by tuning its downcore Al/Ti profile to a well-dated nearby reference core, and carbonate 230Th/U ages were calculated using... |
| Tipo: Text |
Palavras-chave: Gas hydrates; Pockmarks; U-series; Authigenic carbonates; Niger delta. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00286/39708/41518.pdf |
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| Bougault, Henri; Cande, S; Mills, W; Curtis, D; Neuser, R; Christie, D; Rideout, M; Etoubleau, Joel; Drake, N; Brannon, J; Weaver, B; Echols, D; Clark, M; Khan, Mj; Hill, I. |
| Tipo: Text |
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| Ano: 1983 |
URL: http://archimer.ifremer.fr/doc/00311/42189/41490.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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| Barrat, Jean-alix; Dauphas, N.; Gillet, P.; Bollinger, C.; Etoubleau, Joel; Bischoff, A.; Yamaguchi, A.. |
| Thulium is a heavy rare earth element (REE) whose geochemical behavior is intermediate between Er and Yb, and that is not expected to be decoupled from these elements during accretion of planetary bodies and geological processes. However, irregularities in REE volatilities at higher temperature could have decoupled the REEs relative to one another during the early stages of condensation of the solar nebula. Indeed, positive Tm anomalies are found in some refractory inclusions from carbonaceous chondrites, and it is possible that large scale nebular reservoirs displaying positive or negative Tm anomalies were formed during the early history of the solar system. We analyzed a series of meteorites and terrestrial rocks in order to evaluate the existence of Tm... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00302/41338/40524.pdf |
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| Bayon, Germain; Barrat, Jean Alix; Etoubleau, Joel; Benoit, Mathieu; Bollinger, Claire; Revillon, Sidonie. |
| We present a revised method for the determination of concentrations of rare earth (REE) and other trace elements (Y, Sc, Zr, Ba, Hf, Th) in geological samples. Our analytical procedure involves sample digestion using alkaline fusion (NaOH-Na2O2) after addition of a Tm spike, co-precipitation on iron hydroxides, and measurement by sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS). The procedure was tested successfully for various rock types (i.e., basalt, ultramafic rock, sediment, soil, granite), including rocks with low trace element abundances (sub ng g(-1)). Results obtained for a series of nine geological reference materials (BIR-1, BCR-2, UB-N, JP-1, AC-E, MA-N, MAG-1, GSMS-2, GSS-4) are in reasonable agreement with published... |
| Tipo: Text |
Palavras-chave: Digestion des Echantillons; Spike de Tm; ICP MS; MatEriaux de rEfErence; Echantillons gEologiques; ElEments du groupe des Terres Rares; Sample digestion; Tm spike; ICP MS; Reference materials; Geological samples; Rare earth elements. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6449.pdf |
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| Fouquet, Yves; Pelleter, Ewan; Konn, Cecile; Chazot, Gilles; Dupre, Stephanie; Alix, Anne-sophie; Cheron, Sandrine; Donval, Jean-pierre; Guyader, Vivien; Etoubleau, Joel; Charlou, Jean-luc; Labanieh, Shasa; Scalabrin, Carla. |
| The study area is located at the transition between the northern end of the Tonga Trench and the North Fiji fracture zone, where tectonic movements are reputed to be the fastest in the world. To the southeast of Futuna Island, a broad area of volcanism occurs within a region characterized by a change in the tectonic fabric between a NE-SW oriented volcanic graben and the N-S oriented Alofi ridge. In 2010, the active volcano Kulo Lasi, which represents the most recent volcanic episode in the Futuna area, was discovered in the center of this extensive volcanic zone. Kulo Lasi is a 20 km diameter shield volcano that rises 400 m above the seafloor. It is composed of basaltic to trachy-andesitic lava with no obvious geochemical affinity with the Tonga... |
| Tipo: Text |
Palavras-chave: Subaqueous volcanism; Hydrothermal activity; Kulo Lasi caldera; Sulfides; SW Pacific. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00445/55633/57279.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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| Moussa, N.; Boiron, M.c-; Grassineau, N.v.; Asael, Dan; Fouquet, Yves; Le Gall, Bernard; Rolet, Joël; Etoubleau, Joel; Delacourt, Christophe. |
| In this paper, the mineralogy, fluid inclusions and stable isotopes of hydrothermal veins from the SE part of the Afar Rift (Djibouti) were studied. Mineralization occurs as gold-silver in quartz/carbonate veins and is mainly associated with felsic volcanism. The morphologies and textures of quartz show crustiform colloform banding, massive and breccias. Microthermometric measurements were made on quartz-hosted two phases (liquid + vapor) inclusions. Mean homogenization temperature ranges from 150°C to 340°C and ice-melting temperatures range from -0.2°C to - 1.6°C indicating that inclusion solutions contain 0.35 to 2.7 eq. wt. % NaCl. Furthermore, δ18O and δ13C values from calcite range from 3.7 to 26.6 ‰ and -7.5 to 0.3 ‰, respectively. The presence of... |
| Tipo: Text |
Palavras-chave: Fluid inclusions; Stable isotopes; Hydrothermal; Epithermal system; SE Afar Rift; Djibouti. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00494/60528/63991.pdf |
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| Bougault, Henri; Appriou, P; Birolleau, A; Charlou, Jean-luc; Crane, K; Etoubleau, Joel; Fouquet, Yves; Gente, P; Harmegnies, Francois; Landure, Jean-yves; Le Noac'H, A; Pelle, Henri; Sichler, Bertrand; Voisset, Michel; Watremez, Pierre; Vaslet, N; Jean Baptiste, P. |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00070/18104/15652.pdf |
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| Bayon, Germain; Toucanne, Samuel; Skonieczny, Charlotte; Andre, L.; Bermell, Sylvain; Cheron, Sandrine; Dennielou, Bernard; Etoubleau, Joel; Freslon, Nicolas; Gauchery, T.; Germain, Yoan; Jorry, Stephan; Menot, G.; Monin, L.; Ponzevera, Emmanuel; Rouget, M. -l.; Tachikawa, K.; Barrat, Jean-alix. |
| Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world’s major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes. Our results... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00276/38733/37249.pdf |
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| Etoubleau, Joel; Bohn, Marcel; Fouquet, Yves; Cambon, Pierre; Le Suave, Raymond. |
| A range of X-ray analytical techniques contributes particularly well to the mineralogical and geochemical characterisations of cobalt-rich iron and manganese oxides crusts. X-ray diffraction is used to identify the weak crystallinity of the material. Bulk geochemical characterisation of the crusts is done by X-ray fluorescence for the precise determination of ca. thirty major and trace elements. Fine scale analysis is carried out by electron microprobe to quantitatively map the distribution of elements in oxide phases within the crusts. Microprobe work is essential to obtain the chemical composition of the embedded metallic micro-meteorites. |
| Tipo: Text |
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| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00000/10415/9517.pdf |
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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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| Pelleter, Ewan; Fouquet, Yves; Etoubleau, Joel; Cheron, Sandrine; Labanieh, Shasa; Josso, Pierre; Bollinger, Claire; Langlade, Jessica. |
| The Wallis and Futuna back-arc system is a complex area composed of at least two active oceanic spreading centers (Futuna and Alofi spreading centers) and young volcanic zones characterized by diffuse magmatism locally affected by the Samoan hotspot. This geological setting is favorable to the establishment of hydrothermal systems either high-temperature (HT) hydrothermal venting or low-temperature (LT) diffuse flow. During the 2010 Futuna cruise aboard R/V L'Atalante, three remarkable inactive LT Fe-Si-Mn deposits have been discovered (i.e. Utu Uli, Anakele and Utu Sega). Some of the Mn-rich precipitates exhibit the highest base metals concentrations so far recorded in ferromanganese rocks including the well-documented hydrogenetic crusts and polymetallic... |
| Tipo: Text |
Palavras-chave: Hydrothermal; Diffuse flow; Manganese oxyhydroxides; Metal-rich; Seafloor; Wallis and Futuna Island; South-West Pacific. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00350/46164/45862.pdf |
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| Josso, P.; Pelleter, Ewan; Pourret, O.; Fouquet, Yves; Etoubleau, Joel; Cheron, Sandrine; Bollinger, C.. |
| Ferromanganese (Fe-Mn) deposits constitute a ubiquitous mineral type in oceanic settings, with metal (Cu, Ni, Zn, Co, Pt) and rare earth elements (REE) enrichments of potential economic interest. Routine analysis of trace elements by ICP-MS has advanced our understanding of the impact of hydrogenetic, diagenetic and hydrothermal processes on the mobility and interaction of high field strength elements (HFSE: Zr, Ti) and REE and yttrium (REY) with Fe-Mn oxyhydroxides. Recent discoveries in the French exclusive economic zone (EEZ) of Wallis and Futuna (southwest Pacific Ocean) have brought new insight to the formation of low temperature (LT) hydrothermal Mn deposits and lead us to reconsider the classification and discrimination diagrams for of Fe-Mn... |
| Tipo: Text |
Palavras-chave: Ferromanganese mineralization; Hydrogenetic crusts; Nodules; Hydrothermal deposits; Rare earth elements; High field strength elements; Classification. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00350/46156/45854.pdf |
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| Dekov, Vesselin M.; Rouxel, Olivier; Kouzmanov, Kalin; Bindi, Luca; Asael, Dan; Fouquet, Yves; Etoubleau, Joel; Burgaud, Gaetan; Walle, Markus. |
| Active and inactive hydrothermal chimneys composed almost entirely of enargite and luzonite, rare minerals in seafloor hydrothermal deposits, were found at the summits of two submarine volcanoes, North Su and Kaia Natai, in the Manus Back-Arc Basin. Detailed mineralogical and geochemical studies revealed that most probably these deposits precipitated at T = 200°–330 °C and high fS2. The negative δ34S values (− 8.58 to − 3.70‰) of the enargite-luzonite are best explained by disproportionation reactions of magmatic SO2 and suggest that the high fS2 is likely provided by direct magmatic input of SO2 into the hydrothermal system. Fractionation of Cu stable isotopes during the precipitation of enargite-luzonite (δ65Cu ranges from − 0.20 to + 0.35‰) is inferred... |
| Tipo: Text |
Palavras-chave: Enargite; Epithermal; Hydrothermal vent; Luzonite; S-Cu isotopes; Seafloor. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00337/44844/44432.pdf |
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| Bayon, Germain; Dennielou, Bernard; Etoubleau, Joel; Ponzevera, Emmanuel; Toucanne, Samuel; Bermell, Sylvain. |
| About 3000 years ago, a major vegetation change occurred in Central Africa, when rainforest trees were abruptly replaced by savannas. The consensus is that the forest disturbance was caused by climate change. We show here that chemical weathering in Central Africa, reconstructed from geochemical analyses of a marine sediment core, intensified abruptly at the same period, departing significantly from the long-term weathering fluctuations related to the Late Quaternary climate. Evidence that this weathering event was also contemporaneous with the migration of Bantu-speaking farmers across Central Africa suggests that human land-use intensification at that time already had a significant impact on the rainforest. |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00069/18031/15574.pdf |
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| Calves, Gerome; Toucanne, Samuel; Jouet, Gwenael; Charrier, Simon; Thereau, Estelle; Etoubleau, Joel; Marsset, Tania; Droz, Laurence; Bez, M.; Abreu, V.; Jorry, Stephan; Mulder, T.; Lericolais, Gilles. |
| Geophysical data and sampling of the Golo Basin (East Corsica margin) provide the opportunity to study mass balance in a single drainage system over the last 130 kyr, by comparing deposited sediments in the sink and the maximum eroded volume in the source using total denudation proxies. Evaluation of the solid sediments deposited offshore and careful integration of uncertainties from the age model and physical properties allow us to constrain three periods of sedimentation during the last climatic cycle. The peak of sedimentation initiated during Marine Isotopic Stage (MIS) 3 (ca. 45 ka) and lasted until late in MIS 2 (ca. 18 ka). This correlates with Mediterranean Sea palaeoclimatic records and the glaciation in high altitude Corsica. The yield of solid... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00087/19779/17480.pdf |
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| Vlastelic, Ivan; Dosso, Laure; Bougault, Henri; Aslanian, Daniel; Geli, Louis; Etoubleau, Joel; Bohn, Marcel; Joron, Jl; Bollinger, C. |
| Axial bathymetry, major/trace elements, and isotopes suggest:that the Pacific-Antarctic Ridge (PAR) between 56 degrees S and 66 degrees S is devoid of any hotspot influence. PAR (56-66 degrees 5) samples have in-average lower Sr-87/Sr-86 and Nd-143/Nd-144 and higher Pb-206/(204)pb than northern Pacific midocean ridge basalts (MORB), and also than MORE from the other oceans. The high variability of Pb isotopic ratios (compared to Sr and Nd) can be due to either a;general high mu (HIMU) (high U/Pb) affinity of the southern Pacific upper mantle or to a mantle event first recorded in time by Pb isotopes. Compiling the results of this study with those from the PAR between 53 degrees S and 57 degrees S gives a continuous view of mantle characteristics from south... |
| Tipo: Text |
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| Ano: 2000 |
URL: https://archimer.ifremer.fr/doc/00000/10578/9396.pdf |
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| Registros recuperados: 32 | |
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