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| Registros recuperados: 78 | |
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| Tanimizu, Masaharu; Sugiyama, Naoki; Ponzevera, Emmanuel; Bayon, Germain. |
| Isotope ratios of U-236/U-238 were measured at levels below 10(-7) by single collector ICPMS with a tandem quadrupole mass separation mechanism. Peak tailing of the prominent U-238(+) ion beam on the U-236(+) peak was reduced to the level of similar to 10(-10) by use of two quadrupole mass filters. The (UH+)-U-235 interference on U-236(+) was efficiently reduced to a UH+/U+ ratio of 1 x 10(-8) by an ion-molecule reaction between UH+ and O-2 in a collision/reaction cell placed between the two quadrupoles. The resultant detection limit for U-236/U-238 measurement was better than those reported by any other ICPMS study. The U-236/U-238 ratios, measured as (UO+)-U-236-O-16/(UO+)-U-238-O-16, were determined in the range 10(-9) to 10(-7) without correction for... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00152/26358/24440.pdf |
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| Bastian, Luc; Revel, Marie; Bayon, Germain; Dufour, Aurelie; Vigier, Nathalie. |
| Chemical weathering of silicate rocks on continents acts as a major sink for atmospheric carbon dioxide and has played an important role in the evolution of the Earth’s climate. However, the magnitude and the nature of the links between weathering and climate are still under debate. In particular, the timescale over which chemical weathering may respond to climate change is yet to be constrained at the continental scale. Here we reconstruct the relationships between rainfall and chemical weathering in northeast Africa for the last 32,000 years. Using lithium isotopes and other geochemical proxies in the clay-size fraction of a marine sediment core from the Eastern Mediterranean Sea, we show that chemical weathering in the Nile Basin fluctuated in parallel... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00376/48697/49030.pdf |
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| Boswell, Steven M.; Toucanne, Samuel; Pitel-roudaut, Mathilde; Creyts, Timothy T.; Eynaud, Frédérique; Bayon, Germain. |
| Heinrich events (HEs) are dramatic episodes of marine-terminating ice discharge and sediment rafting during periods of cold North Atlantic climate. However, the causal chain of events leading to their occurrence is unresolved. Here, we demonstrate that enhanced surface melting of land-terminating margins of the southern Fennoscandian Ice Sheet (FIS) is a recurring feature of Heinrich stadials (HSs), the cold periods during which HEs occur. We use neodymium isotopes to show that the Channel River transported detrital sediments from the interior of eastern Europe to the Bay of Biscay in the northeast Atlantic Ocean at ca. 158–154 ka. Based on similar evidence from the last glacial period, we infer that this interval corresponds to the melting and retreat of... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00499/61065/64596.pdf |
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| Wang, Xudong; Li, Niu; Feng, Dong; Hu, Yu; Bayon, Germain; Liang, Qianyong; Tong, Hongpeng; Gong, Shanggui; Tao, Jun; Chen, Duofu. |
| Cold seeps frequently occur at the seafloor along continental margins. The dominant biogeochemical processes at cold seeps are the combined anaerobic oxidation of methane and sulfate reduction, which can significantly impact the global carbon and sulfur cycles. The circulation of methane-rich fluids at margins is highly variable in time and space, and assessing past seepage activity requires the use of specific geochemical markers. In this study, we report multiple sedimentary proxy records for three piston gravity cores (QDN-14A, QDN-14B, and QDN-31) from the Haima seep of the South China Sea (SCS). By combining total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), acid insoluble carbon and sulfur isotope... |
| Tipo: Text |
Palavras-chave: Cold seep; Anaerobic oxidation of methane; Carbon and sulfur isotopes; South China Sea. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00465/57662/59858.pdf |
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| Bayon, Germain; De Deckker, Patrick; Magee, John W.; Germain, Yoan; Bermell, Sylvain; Tachikawa, Kazuyo; Norman, Marc D.. |
| Millennial-scale cooling events termed Heinrich Stadials punctuated Northern Hemisphere climate during the last glacial period. Latitudinal shifts of the intertropical convergence zone (ITCZ) are thought to have rapidly propagated these abrupt climatic signals southward, influencing the evolution of Southern Hemisphere climates and contributing to major reorganisation of the global ocean-atmosphere system. Here, we use neodymium isotopes from a marine sediment core to reconstruct the hydroclimatic evolution of subtropical Australia between 90 to 20 thousand years ago. We find a strong correlation between our sediment provenance proxy data and records for western Pacific tropical precipitations and Australian palaeolakes, which indicates that Northern... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00375/48585/48906.pdf |
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| Tallobre, Cedric; Loncke, Lies; Bassetti, Maria-angela; Giresse, Pierre; Bayon, Germain; Buscail, Roselyne; De Madron, Xavier Durrieu; Bourrin, Francois; Vanhaesebroucke, Marc; Sotin, Christine. |
| The Demerara Plateau, belonging to the passive transform margin of French Guiana, was investigated during the IGUANES cruise in 2013. The objectives of the cruise were to explore the poorly-known surficial sedimentary column overlying thick mass transport deposits as well as to understand the factors controlling recent sedimentation. The presence of numerous bedforms at the seafloor was observed thanks to newly acquired IGUANES bathymetric, high resolution seismic and chirp data, while sediment cores allowed the characterization of the deposits covering the mass transport deposits. Modern oceanographic conditions were determined in situ, using mooring monitoring over a 10-month period. Our data indicate the presence of a Contourite Depositional System... |
| Tipo: Text |
Palavras-chave: Marginal plateau; Contourite; Comet tail; Demerara Plateau. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00308/41957/41220.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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| Howe, Jacob N. W.; Piotrowski, Alexander M.; Noble, Taryn L.; Mulitza, Stefan; Chiessi, Cristiano M.; Bayon, Germain. |
| Changes in deep ocean ventilation are commonly invoked as the primary cause of lower glacial atmospheric CO2. The water mass structure of the glacial deep Atlantic Ocean and the mechanism by which it may have sequestered carbon remain elusive. Here we present neodymium isotope measurements from cores throughout the Atlantic that reveal glacial-interglacial changes in water mass distributions. These results demonstrate the sustained production of North Atlantic Deep Water under glacial conditions, indicating that southern-sourced waters were not as spatially extensive during the Last Glacial Maximum as previously believed. We demonstrate that the depleted glacial delta C-13 values in the deep Atlantic Ocean cannot be explained solely by water mass source... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00343/45386/44888.pdf |
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| Bayon, Germain; Schefuss, Enno; Dupont, Lydie; Borges, Alberto V.; Dennielou, Bernard; Lambert, Thibault; Mollenhauer, Gesine; Monin, Laurence; Ponzevera, Emmanuel; Skonieczny, Charlotte; Andre, Luc. |
| There is increasing evidence that abrupt vegetation shifts and large-scale erosive phases occurred in Central Africa during the third millennium before present. Debate exists as to whether these events were caused by climate change and/or intensifying human activities related to the Bantu expansion. In this study, we report on a multi-proxy investigation of a sediment core (KZR-23) recovered from the Congo submarine canyon. Our aim was to reconstruct climate, erosion and vegetation patterns in the Congo Basin for the last 10,000 yrs, with a particular emphasis on the late Holocene period. Samples of modern riverine suspended particulates were also analyzed to characterize sediment source geochemical signatures from across the Congo watershed. We find that... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Suspended particulates; Congo Basin; ENSO; Human land-use; Deforestation. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00463/57467/59747.pdf |
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| Hardy, William; Penaud, Aurelie; Marret, Fabienne; Bayon, Germain; Marsset, Tania; Droz, Laurence. |
| A new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts (dinocysts) is presented from a marine sediment core collected on the Congolese margin with the aim of reconstructing past hydrological changes in the equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. Our high-resolution dinocyst record indicates that significant temperature and moisture variations occurred across the glacial period, the last deglaciation and the Holocene. The use of specific dinocyst taxa, indicative of fluvial, upwelling and Benguela Current past environments for instance, provides insights into the main forcing mechanisms controlling palaeohydrological changes on orbital timescales. In particular, we are able, for the last 44 kyr, to... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00349/46006/45675.pdf |
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| Dera, Guillaume; Prunier, Jonathan; Smith, Paul L.; Haggart, James W.; Popov, Evgeny; Guzhov, Alexander; Rogov, Mikhail; Delsate, Dominique; Thies, Detlev; Cuny, Gilles; Puceat, Emmanuelle; Charbonnier, Guillaume; Bayon, Germain. |
| The breakup of Pangea and onset of growth of the Pacific plate led to several paleoenvironmental feedbacks, which radically affected paleoclimate and ocean chemistry during the Jurassic. Overall, this period was characterized by intense volcanic degassing from large igneous provinces and circum-Panthalassan arcs, new oceanic circulation patterns, and changes in heat and humidity transports affecting continental weathering. Few studies, however, have attempted to unravel the global interactions linking these processes over the long-term. In this paper, we address this question by documenting the global changes in continental drainage and surface oceanic circulation for the whole Jurassic period. For this purpose, we present 53 new neodymium isotope values... |
| Tipo: Text |
Palavras-chave: Neodymium isotopes; Jurassic; Paleoclimate; Paleoceanography; Continental drainage. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00179/29015/27443.pdf |
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| Bonneau, Lucile; Toucanne, Samuel; Bayon, Germain; Jorry, Stephan; Emmanuel, Laurent; Silva Jacinto, Ricardo. |
| In this study we used major element composition, neodymium isotopes ratios (εNdεNd) and concentration of REE to track and quantify the sediment routing in the Var sedimentary system from source (Southern French Alps) to sink (Ligurian Sea) over the last 50 ka. Our data reveal that changes in sediment sources over that period, associated with concomitant changes in the hyperpycnal (i.e. flood-generated turbidity currents) activity in the Var submarine canyon, were mainly driven by paleoenvironmental conditions in the upper basin and in particular by the presence of glaciers during the last glacial period. Based on this evidence, we determined when and how glacier-derived sediments were produced, then excavated and transferred to the ocean, allowing us to... |
| Tipo: Text |
Palavras-chave: Var; Routing system; Glacial erosion; Source-to-sink. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00358/46957/47130.pdf |
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| Huguen, Caroline; Foucher, Jean-paul; Mascle, J.; Ondreas, Helene; Thouement, M.; Gontharet, S.; Stadnitskaia, A.; Pierre, C.; Bayon, Germain; Loncke, L.; Boetius, A.; Bouloubassi, I.; De Lange, G.; Caprais, Jean-claude; Fouquet, Yves; Woodside, J.; Dupre, Stephanie. |
| This paper reports the first "in situ" seafloor observations of fluid escape structures in a fault-controlled caldera-type depression of about 8 km diameter, named the Menes caldera, in the Eastern Mediterranean sea off Egypt (western province of the Nile Deep Sea Fan). A detailed analysis of seven Nautile dives, performed during the Nautinil cruise in 2003, focused on determining the nature, origin, importance, mechanisms and environmental impacts of the fluid escape processes from the geological observations. Seafloor maps, constructed from direct visual observations and video records made from the submersible, and sampling results, for three mud volcanoes of the caldera, Cheops, Chephren and Mykerinos show differences in activity but many common... |
| Tipo: Text |
Palavras-chave: Mediterranean Sea; Nile Deep Sea Fan; Mud volcano; Brine seep. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00000/11089/10627.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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| Won, Eun-ji; Kim, Seung Hee; Go, Young-shin; Kumar, K. Suresh; Kim, Min-seob; Yoon, Suk-hee; Bayon, Germain; Kim, Jung-hyun; Shin, Kyung-hoon. |
| The increasing global consumption of seafood has led to increased trade among nations, accompanied by mislabeling and fraudulent practices that have rendered authentication crucial. The multi-isotope ratio analysis is considered as applicable tool for evaluating geographical authentications but requires information and experience to select target elements such as isotopes, through a distinction method based on differences in habitat and physiology due to origin. The present study examined recombination conditions of multi-elements that facilitated geographically distinct classifications of the clams to sort out appropriate elements. Briefly, linear discriminant analysis (LDA) analysis was performed according to several combinations of five stable isotopes... |
| Tipo: Text |
Palavras-chave: Authentication; Manila clam; Stable isotope; Traceability; Linear discriminant analysis. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00685/79701/82488.pdf |
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| Francke, Alexander; Holtvoeth, Jens; Codilean, Alexandru; Lacey, Jack H.; Bayon, Germain; Dosseto, Anthony. |
| Understanding and quantifying the processes and geochemical cycles associated with catchment erosion, the development of soils and weathering horizons, and terrestrial habitat change beyond the scales of modern observations remain challenging. Such research, however, has become increasingly important to help predict future landscape change in light of increasing land use and rapid global warming. We herein review organic and inorganic geochemical tools applied to depositional archives to better understand various aspects of landscape evolution on geological time scales. We highlight the potentials and limitations of inorganic geochemical analytical methods, such as major element geochemistry, metal and radiogenic isotopes, and in-situ cosmogenic nuclides,... |
| Tipo: Text |
Palavras-chave: Quaternary landscape evolution; Catchment erosion; Terrestrial habitat change; Land use; Fluvial; Lacustrine; Inorganic geochemistry; Organic geochemistry; Radiogenic isotopes; Metal isotopes; Uranium isotopes; Cosmogenic nuclides. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00632/74383/74084.pdf |
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| Cheron, Sandrine; Etoubleau, Joel; Bayon, Germain; Garziglia, Sebastien; Boissier, Audrey. |
| The aim of this study is to investigate the information provided by sulfur count rates obtained by X-ray fluorescence core scanner (XRF-CS) along sedimentary records. The analysis of two marine sediment cores from the Niger Delta margin shows that XRF-CS sulfur count rates obtained at the surface of split core sections with XRF-CS correlate with both direct quantitative pyrite concentrations, as inferred from X-ray powder diffraction (XRD) and sulfur determination by wavelength dispersive X-ray fluorescence (WD-XRF) spectrometry, and total dissolved sulfide (TDS) contents in the sediment pore water. These findings demonstrate the potential of XRF-CS for providing continuous profiles of pyrite distribution along split sections of sediment cores. The... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00346/45731/45376.pdf |
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| Bayon, Germain; Birot, Dominique; Bollinger, Claire; Barrat, Jean Alix. |
| We report on an improved method for determining trace element abundances in seawater and other natural waters. The analytical procedure involves co-precipitation on iron hydroxides after addition of a Tm spike, and measurement by inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). The validity of the method was assessed through a series of co-precipitation experiments, using ultra-diluted solutions of a certified rock reference material (BIR-1). Results obtained for four natural water reference materials (NASS-5, CASS-4, SLEW-3, SLRS-4) are in agreement with published working values for rare earth elements, yttrium, vanadium and, when available, for hafnium, zirconium, thorium and scandium. A set of proposed values with uncertainties... |
| Tipo: Text |
Palavras-chave: Seawater; Reference material; ICP-MS; Trace elements; Rare earth elements; Eau de mer; Materiau de reference; ICP-MS; Elements traces; Terres Rares. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00031/14189/18000.pdf |
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| Registros recuperados: 78 | |
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