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1. Active hydrothermal vents in the Woodlark Basin may act as dispersing centres for hydrothermal fauna

Author: Cédric Boulart, Olivier Rouxel, Carla Scalabrin, Pierre Le Meur, Ewan Pelleter, Camille Poitrimol, Eric Thiébaut, Marjolaine Matabos, Jade Castel, Adrien Tran Lu Y, Loic N. Michel, Cécile Cathalot, Sandrine Chéron, Audrey Boissier, Yoan Germain, Vivien Guyader, Sophie Arnaud-Haond, François Bonhomme, Thomas Broquet, Valérie Cueff-Gauchard, Victor Le Layec, Stéphane L’Haridon, Jean Mary, Anne-Sophie Le Port, Aurélie Tasiemski, Darren C. Kuama, Stéphane Hourdez, and Didier Jollivet
Subjects: Geology, QE1-996.5, Environmental sciences, GE1-350
Abstract: La Scala Vent Field, near the Solomon Islands in the Pacific Ocean, comprises diffuse vents and vigorous black smokers and hosts large beds of stalked barnacles and bacterial mats at vent peripheries, according to ship-borne multi-beam echo sounding and remotely operated vehicle surveys.
Published: 2022
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2. Hydrothermal plumes as hotspots for deep-ocean heterotrophic microbial biomass production

Author: Cécile Cathalot, Erwan G. Roussel, Antoine Perhirin, Vanessa Creff, Jean-Pierre Donval, Vivien Guyader, Guillaume Roullet, Jonathan Gula, Christian Tamburini, Marc Garel, Anne Godfroy, and Pierre-Marie Sarradin
Subjects: Science
Abstract: Hydrothermal vents are biogeochemically important, but their contribution to the carbon cycle is poorly constrained. Here the authors build a biogeochemical model that estimates autotrophic and heterotrophic production rates of microbial communities within hydrothermal plumes along mid-ocean ridges.
Published: 2021
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3. Inter-Comparison of the Spatial Distribution of Methane in the Water Column From Seafloor Emissions at Two Sites in the Western Black Sea Using a Multi-Technique Approach

Author: Roberto Grilli, Dominique Birot, Mia Schumacher, Jean-Daniel Paris, Camille Blouzon, Jean Pierre Donval, Vivien Guyader, Helene Leau, Thomas Giunta, Marc Delmotte, Vlad Radulescu, Sorin Balan, Jens Greinert, and Livio Ruffine
Subjects: dissolved gas, methane, black sea, in situ measurements, gas seepages, instrumental inter-comparison, Science
Abstract: Understanding the dynamics and fate of methane (CH4) release from oceanic seepages on margins and shelves into the water column, and quantifying the budget of its total discharge at different spatial and temporal scales, currently represents a major scientific undertaking. Previous works on the fate of methane escaping from the seafloor underlined the challenge in both, estimating its concentration distribution and identifying gradients. In April 2019, the Envri Methane Cruise has been conducted onboard the R/V Mare Nigrum in the Western Black Sea to investigate two shallow methane seep sites at ∼120 m and ∼55 m water depth. Dissolved CH4 measurements were conducted with two continuous in-situ sensors: a membrane inlet laser spectrometer (MILS) and a commercial methane sensor (METS) from Franatech GmbH. Additionally, discrete water samples were collected from CTD-Rosette deployment and standard laboratory methane analysis was performed by gas chromatography coupled with either purge-and-trap or headspace techniques. The resulting vertical profiles (from both in situ and discrete water sample measurements) of dissolved methane concentration follow an expected exponential dissolution function at both sites. At the deeper site, high dissolved methane concentrations are detected up to ∼45 m from the seabed, while at the sea surface dissolved methane was in equilibrium with the atmospheric concentration. At the shallower site, sea surface CH4 concentrations were four times higher than the expected equilibrium value. Our results seem to support that methane may be transferred from the sea to the atmosphere, depending on local water depths. In accordance with previous studies, the shallower the water, the more likely is a sea-to-atmosphere transport of methane. High spatial resolution surface data also support this hypothesis. Well localized methane enriched waters were found near the surface at both sites, but their locations appear to be decoupled with the ones of the seafloor seepages. This highlights the need of better understanding the processes responsible for the transport and transformation of the dissolved methane in the water column, especially in stratified water masses like in the Black Sea.
Published: 2021
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4. Processes Driving Iron and Manganese Dispersal From the TAG Hydrothermal Plume (Mid-Atlantic Ridge): Results From a GEOTRACES Process Study

Author: David González-Santana, Hélène Planquette, Marie Cheize, Hannah Whitby, Arthur Gourain, Thomas Holmes, Vivien Guyader, Cécile Cathalot, Ewan Pelleter, Yves Fouquet, and Géraldine Sarthou
Subjects: iron, manganese, hydrothermal, TAG, Mid Atlantic Ridge, GEOTRACES, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract: Hydrothermal vents are a recognized source of trace elements to the ocean inventory. Nevertheless, the contribution of slow-spreading ridges remains poorly resolved. To address this, high-resolution dissolved (
Published: 2020
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5. Extending the dataset of fluid geochemistry of the Menez Gwen, Lucky Strike, Rainbow, TAG and Snake Pit hydrothermal vent fields: Investigation of temporal stability and organic contribution

Author: A.S. Alix, Erwan Roussel, Vivien Guyader, Yoan Germain, Olivier Rouxel, Cecile Konn, and Jean-Pierre Donval
Subjects: Geochemistry, Magma chamber, Aquatic Science, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Hydrothermal circulation, 03 medical and health sciences, Hydrothermal systems, Organic geochemistry, Organic matter, 030304 developmental biology, 0105 earth and related environmental sciences, chemistry.chemical_classification, Total organic carbon, 0303 health sciences, Major and minor elements, Abiogenic petroleum origin, chemistry, 13. Climate action, Fluid geochemistry, Seawater, Gases, Geology, Hydrothermal vent
Abstract: The Menez Gwen, Lucky Strike, Rainbow, TAG (Transatlantic Geotraverse) and Snake Pit hydrothermal vent fields on the Mid-Atlantic Ridge were revisited and resampled for geochemical investigation during the BIOBAZ 2013 and BICOSE 2014 research cruises. Geochemical analysis of the major and minor elements of the hydrothermal fluid and concentrations of gases extends and complements the existing dataset. Our results are consistent with values previously reported and fall within the range of the analytical error. This indicates that the hydrothermal vent field system has remained relatively stable over the last few decades. However, some differences were observed and (i) suggested a recent eruption at Menez Gwen, (ii) supported the occurrence of low-temperature serpentinisation in this same site, (iii) supported a change in the reaction zone or axial magma chamber (AMC) depth at Lucky Strike, (iv) an increase of the temperature at depth at Snake Pit and (v) supported the hypothesis of large seawater entrainment through the TAG hydrothermal mound. Besides, it is possible that small temporal and spatial scale processes may control a significant part of the geochemistry, owing to the fact that some variations in the data could not be interpreted. However, our investigation of the organic geochemistry represents a pioneering addition to research for Menez Gwen, Snake Pit and TAG and a much more comprehensive study for Lucky Strike and Rainbow. Concentrations for a wide variety of semi volatile organic compounds (SVOCs) were obtained for the first time at all sites. Our results showed that a great part of the total organic carbon (TOC) could not be allocated by the total SVOCs studied here, suggesting that other processes/sources of organic carbon remain to be identified. The TAG organic geochemistry seemed entirely based on thermogenic processes whereas mixed processes may occur at the other vent field. The presence of n-alkanes suggested the contribution of a low-temperature fluid at all sites. An additional high-temperature organic matter degradation component was likely present at Menez Gwen and Lucky Strike. Our results also indicated that both abiogenic and biogenic processes produced organic compounds. Therefore, we suggest that a portion of the fatty acids at Menez Gwen and polyaromatic hydrocarbons (PAHs) at Rainbow may be derived from abiogenic processes, whereas biogenic processes could be responsible for the presence of n-fatty acids (n-FAs) at Lucky Strike and Rainbow. Moreover, organic geochemistry data appeared to be helpful in understanding some inorganic processes.
Published: 2022

6. A GC-SSIM-CRDS System: Coupling a Gas Chromatograph with a Cavity Ring-Down Spectrometer for Onboard Twofold Analysis of Molecular and Isotopic Compositions of Natural Gases during Ocean-Going Research Expeditions

Author: Jean-Claude Caprais, Vivien Guyader, Jean-Pierre Donval, Nolwenn LeCuff, Christophe Brandily, Alexis de Prunelé, Cecile Cathalot, Livio Ruffine, and Claire Croguennec
Subjects: Chromatography, Gas, Analytical chemistry, Natural Gas, Natural gases, Biochemistry, Methane, Analytical Chemistry, Cavity ring-down spectroscopy, Carbon cycle, chemistry.chemical_compound, Natural gas, Environmental Chemistry, Spectroscopy, Packed bed, Stable carbon isotope ratio, Carbon Isotopes, Gas chromatography, business.industry, Spectrum Analysis, Coupled analytical technique, chemistry, Carbon dioxide, Onboard analysis, Isotopes of carbon, Molecular composition, Expeditions, Gases, business
Abstract: Carbon dioxide (CO2) and methane (CH4) are two climate-sensitive components of gases migrating within sediments and emitted into the water column on continental margins. They are involved in several key biogeochemical processes entering into the global carbon cycle. In order to perform onboard measurements of both the molecular and stable carbon isotope ratios (δ13C) of CH4 and CO2 of natural gases during oceanic cruises, we have developed a novel approach coupling gas chromatography (GC) with cavity ring-down spectroscopy (CRDS). The coupled devices are connected to a small sample isotope module (SSIM) to form a system called GC-SSIM-CRDS. Small volumes of natural gas samples (
Published: 2021

7. Birth of a large volcanic edifice offshore Mayotte via lithosphere-scale dyke intrusion

Author: Angèle Laurent, Philippe Kowalski, R. Daniel, Eric Jacques, Patrick Bachèlery, Raphaël Grandin, Manuel A. Moreira, Aline Peltier, Valérie Ballu, Nathalie Feuillet, François Beauducel, Jean-Pierre Donval, Arnaud Gaillot, Didier Bertil, Yves Fouquet, Vivien Guyader, Fabien Paquet, Arnaud Lemarchand, Cecile Cathalot, Simon Besançon, Emmanuel Rinnert, Chastity Aiken, Carla Scalabrin, Wayne C Crawford, Isabelle Thinon, Jean Marie Saurel, Océane Foix, Anne Lemoine, Pascal Pelleau, Christine Deplus, Louis Géli, Stephan J. Jorry, J. Gomez, Claudio Satriano, Pascal Bernard, Jérôme Van der Woerd, Institut de Physique du Globe de Paris (IPG Paris), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institut Terre Environnement Strasbourg (ITES), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), French Ministries of Environment, Research and Overseas under a research project to N.F. (proposal INSU-CT3 TELLUS SISMAYOTTE2019)., Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPC), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Magma - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Institut national des sciences de l'Univers (INSU - CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institut de physique du globe de Strasbourg (IPGS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), and Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 010502 geochemistry & geophysics, 01 natural sciences, Seafloor spreading, Submarine eruption, Volcano, [SDU]Sciences of the Universe [physics], Lithosphere, Asthenosphere, Magma, General Earth and Planetary Sciences, Caldera, 14. Life underwater, Petrology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Volcanic eruptions shape Earth’s surface and provide a window into deep Earth processes. How the primary asthenosphericmelts form, pond and ascend through the lithosphere is, however, still poorly understood. Since 10 May 2018, magmaticactivity has occurred offshore eastern Mayotte (North Mozambique channel), associated with large surface displacements,very-low-frequency earthquakes and exceptionally deep earthquake swarms. Here we present geophysical and marine datafrom the MAYOBS1 cruise, which reveal that by May 2019, this activity formed an 820-m-tall, ~5 km³ volcanic edifice on the seafloor.This is the largest active submarine eruption ever documented. Seismic and deformation data indicate that deep (>55 kmdepth) magma reservoirs were rapidly drained through dykes that intruded the entire lithosphere and that pre-existing subverticalfaults in the mantle were reactivated beneath an ancient caldera structure. We locate the new volcanic edifice at the tip ofa 50-km-long ridge composed of many other recent edifices and lava flows. This volcanic ridge is an extensional feature insidea wide transtensional boundary that transfers strain between the East African and Madagascar rifts. We propose that the massiveeruption originated from hot asthenosphere at the base of a thick, old, damaged lithosphere.
Published: 2021
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8. Birth of a large volcanic edifice through lithosphere-scale dyking offshore Mayotte (Indian Ocean)

Author: Nathalie Feuillet, Stephan Jorry, Wayne Crawford, Christine Deplus, Isabelle Thinon, Eric Jacques, Jean-Marie Saurel, Anne Lemoine, Fabien Paquet, Claudio Satriano, Chastity Aiken, Océane Foix, Philippe Kowalski, Angèle Laurent, Emmanuel. Rinnert, Cecile Cathalot, Jean.Pierre Donval, Vivien Guyader, Arnaud Gaillot, carla scalabrin, Manuel Moreira, Aline Peltier, François Beauducel, Raphaël Grandin, Valérie Ballu, Romuald Daniel, Pascal Pelleau, Simon Besancon, Louis Geli, Pascal Bernard, Patrick Bachelery, Yves Fouquet, Didier Bertil, Arnaud Lemarchand, and Jerôme Van der Woerd
Published: 2021
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9. Effects of postglacial seawater intrusion on sediment geochemical characteristics in the Romanian sector of the Black Sea

Author: Sandrine Cheron, Florian Scholz, Christian Deusner, Samuel Toucanne, Matthias Haeckel, Elke Kossel, Jean-Pierre Donval, Audrey Boissier, Mark Schmidt, Stephan Ker, Vivien Guyader, Livio Ruffine, Vincent Riboulot, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), and Helmholtz Centre for Ocean Research [Kiel] (GEOMAR)
Subjects: inorganic chemicals, Methane oxidation, 010504 meteorology & atmospheric sciences, Stratigraphy, Alkalinity, 010502 geochemistry & geophysics, Oceanography, Gas seeps, 01 natural sciences, chemistry.chemical_compound, Black sea, Silicate minerals, ddc:550, Organic matter, 14. Life underwater, Danube delta, Sulfate, 0105 earth and related environmental sciences, chemistry.chemical_classification, Sediment, Geology, Clay minerals, Geophysics, chemistry, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental chemistry, Iron reduction, Anaerobic oxidation of methane, Sulfate reduction, Carbonate, Economic Geology
Abstract: Highlights • Geochemical analyses highlight multiple diagenesis processes occurring in the sediment. • Intense methane seepages and organic matter degradation contribute to the sulfate reduction. • Chemical of dissolved and mineral iron species indicate that iron is associated with clay minerals. • In response to seawater intrusion, ion exchange, dissolution and reverse weathering reactions change the composition of clay constituting the sediment. Abstract Pore water and sediment geochemistry in the western Black Sea were investigated on long Calypso piston core samples. Using this type of coring device facilitates the recovery of the thick sediment record necessary to analyze transport-reaction processes in response to the postglacial sea-level rise and intrusion of Mediterranean salt water 9 ka ago, and thus, to better characterize key biogeochemical processes and process changes in response to the shift from lacustrine to marine bottom water composition. Complementary data indicate that organic matter degradation occurs in the upper 15 m of the sediment column. However, sulfate reduction coupled with Anaerobic Methane Oxidation (AOM) is the dominant electron-accepting process and characterized by a shallow Sulfate Methane Transition Zone (SMTZ). Net silica dissolution, total alkalinity (TA) maxima and carbonate peaks are found at shallow depths. Pore water profiles clearly show the uptake of K+, Mg2+ and Na + by, and release of Ca2+ and Sr2+ from the heterogeneous lacustrine sediments, which is likely controlled by chemical reactions of silicate minerals and changes in clay mineral composition. Iron (Fe2+) and manganese (Mn2+) maxima largely coincide with Ca2+ peaks and suggest a close link between Fe2+, Mn2+ and Ca2+ release. We hypothesize that the Fe2+ maxima below the SMTZ result from deep Fe3+ reduction linked to organic matter degradation, either driven by DOC escaping from the shallow sulfate reduction zone or slow degradation of recalcitrant POC. The chemical analysis of dissolved and solid iron species indicates that iron is essentially associated with clay minerals, which suggests that microbial iron reduction is influenced by clay mineral composition and bioavailability of clay mineral-bound Fe(III). Overall, our study suggests that postglacial seawater intrusion plays a major role in shaping redox zonation and geochemical profiles in the lacustrine sediments of the Late Quaternary.
Published: 2021
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10. A simple method for the preparation and injection of gas mixtures into a gas chromatograph using a two-component device

Author: Vivien Guyader, E. Boissy, Jean-Pierre Donval, Unité de recherche Géosciences Marines (Ifremer) (GM), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
Subjects: Chromatography, Gas, Hydrogen, chemistry.chemical_element, Sampling valve, Gas mixtures, 010402 general chemistry, 01 natural sciences, Biochemistry, Methane, Analytical Chemistry, law.invention, chemistry.chemical_compound, law, [CHIM]Chemical Sciences, Gas chromatography, Chromatography, Chemistry, 010401 analytical chemistry, Organic Chemistry, General Medicine, Injector, Carbon Dioxide, Reference Standards, 0104 chemical sciences, Volume (thermodynamics), 13. Climate action, Carbon dioxide, Calibration, Seawater, Gases
Abstract: Environmental sciences are expanding and are based on standardized and certified calibrations when measurements are required. When a gaseous composition is quantified, commercial standards are used. Here, we report on a two-component device for the preparation and injection of gas mixtures at the appropriate levels of pressure and volume. The two-component calibrator/injector can be used simultaneously or separately depending on the experimental objective but their combination is extremely effective for injecting gas mixtures at low concentrations. The quantity of gas introduced into a gas chromatograph with the injector can be adapted to the sensitivity of the detector or to avoid column overload. The calibrator provides for a large range of gas-mixture concentrations, from ppm to % mol/mol with an error of preparation of around 1% and an accuracy of less than 3%. This device prepares a variety of gas mixtures (hydrogen, methane and dioxide of carbon) which are compared with certified mixtures by means of gas chromatographic measurements. The results show good agreement between prepared and certified mixtures with a maximum difference of 2% which remains within the relative error of commercial standard. In addition, the preparation of dissolved methane at different concentrations in seawater is presented as a direct application of the calibrator.
Published: 2020
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11. Measuring methane from the seafloor to the atmosphere: an integrated experiment in the Black Sea

Author: Thomas Giunta, Francesco Italiano, Jean-Daniel Paris, Livio Ruffine, Mia Schumacher, Camille Blouzon, Dominique Birot, Vivien Guyader, Gianluca Lazzaro, Marc Delmotte, Jean-Pierre Donval, Sergio Scire, Jens Greinert, Manfredi Longo, Helene Leau, Thibault Douillard, Carla Scalabrin, Sorin Balan, and Roberto Grilli
Subjects: Atmosphere, chemistry.chemical_compound, chemistry, Environmental science, Black sea, Atmospheric sciences, Seafloor spreading, Methane
Abstract: Methane is an important greenhouse gas and an energy resource. Methane in sea water can originate from microbially-mediated organic matter (OM) degradation processes at shallow depth within the sediments, or from thermal cracking of refractory OM at deeper depth. On continental margins, this methane is stored in specific sedimentological bodies or as gas hydrates, or is released at the seafloor as submarine geological seeps followed by its oxidation in the water mass. However, methane released at the seafloor may not entirely be oxidized in the water column and a fraction of it may ultimately reach the atmosphere. The factors that govern the magnitude of methane transfer through the water column to the atmosphere remain poorly known. It has been identified that the amount of methane transferred to the atmosphere is strongly dependent on sites, and the thickness of the water column plays a critical role.The Black Sea shelf and margin are known to host a large number of strong methane seepages. It has therefore been identified as a perfect candidate to investigate the fate of methane released from the seafloor to the atmosphere. This area can also act as a proxy for investigating the fate of methane in potential scenarios of hydrate destabilization in a changing climate, which can become a societal problem in the future. In the frame of ENVRIplus H2020 project (www.envriplus.eu) we developed a joint pilot experiment to measure methane transfer from the seafloor to the atmosphere, in a pilot study involving European research infrastructures ICOS, Eurofleets, EMSO and ACTRIS. We investigated the influence of depth by mapping CH4 concentration and bubble distribution at two different sites, at 60m and 100m water depth, respectively. The pilot experiment developed joint monitoring strategy for methane detection at various levels starting from the seafloor and moving across the water column, the water/air interface and the atmosphere. An EK80 echosounder was used to identify emission areas through massive bubble plumes. The methodology applied integrates (1) sampling from the geosphere, hydrosphere and atmosphere for laboratory measurements of methane concentration by well-proven standard methods together with δ13CH4 analysis, (2) in situ measurements of methane concentration into the water column and the atmosphere, and (3) the deployment of a seafloor observatory for a short monitoring period (4-5 days) to evaluate the temporal variability of gas fluxes.During the cruise we found several occurrences of bubble plumes extending near the surface. Our measurements indicate that dissolved methane concentration drastically decreases from the seafloor to the water surface, highlighting its degradation and dispersion along the pathway to the atmosphere. The atmospheric data suggests a consistent input of marine methane to the atmosphere at the shallower site,. Our study highlights the observational challenges both for the measurement of methane from in situ and laboratory methods, and for the estimation of sea surface fluxes.
Published: 2020
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12. Birth of a large volcanic edifice offshore Mayotte (Comoros Island, Western Indian Ocean)

Author: Jérôme Van der Woerd, Didier Bertil, Arnaud Gaillot, Jean-Marie Saurel, Nathalie Feuillet, Claudio Satriano, Vivien Guyader, Louis Géli, François Beauducel, Stephan J. Jorry, Philippe Kowalski, J. Gomez, Patrice Pelleau, Valérie Ballu, Isabelle Thinon, Pascal Bernard, Chastity Aiken, Jean-Pierre Donval, Emmanuel Rinnert, Yves Fouquet, Wayne C Crawford, Manuel A. Moreira, Anne Lemoine, Fabien Paquet, Angèle Laurent, Cecile Cathalot, Carla Scalabrin, R. Daniel, Eric Jacques, Christine Deplus, Raphaël Grandin, Patrick Bachèlery, Aline Peltier, Océane Foix, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Indian ocean, geography, Oceanography, geography.geographical_feature_category, Volcano, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 13. Climate action, Submarine pipeline, ComputingMilieux_MISCELLANEOUS, Geology
Abstract: Volcanic eruptions are foundational events shaping the Earth’s surface and providing a window into deep Earth processes. We document here an ongoing magmatic event offshore Mayotte island (Western Indian Ocean) unprecedented in terms of emitted volume of lava and duration of the seismic crisis.This event gave birth to a deep-sea volcanic edifice 820m tall and ~ 5 km3 in volume, located 50 km from Mayotte. A plume with distinct chemical signatures compared to open-ocean seawater emanated from the edifice, generating an exceptional 1900m-high vertical acoustic anomaly in the water column. Noble gas analyses in the vesicles from a popping rock dredged on the flank of the edifice, indicate rapid magma transfer from the asthenosphere. The edifice is located at the tip of a WNW-ESE–striking volcanic ridge composed of many other edifices, cones and lava flows constructed by past eruptions. Starting in May 2018 thousand of earthquakes were triggered by the magmatic event. The space-time distribution of the seismicity suggests that magma below the center of the ridge was transported to the new edifice over a few weeks in dikes that penetrated the brittle mantle a result of a lithosphere-scale extensional episode accommodating motion along a transfer zone between the East-African rifts and Madagascar. Since the eruption’s onset, the seismicity is mostly concentrated closer to the island, in an exceptionally deep zone (25-50 km) overlain by a zone of enigmatic, very low frequency, tremors.
Published: 2020
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13. Focused hydrocarbon-migration in shallow sediments of a pockmark cluster in the Niger Delta (Off Nigeria)

Author: Claire Croguennec, Marc Lescanne, Abdulkarim Rabiu, Vivien Guyader, Germain Bayon, Thomas Pape, Gerhard Bohrmann, Nabil Sultan, Vincent Riboulot, E. Cauquil, Yoan Germain, Jean Pierre Donval, Claire Bollinger, Jean Claude Caprais, Alexis de Prunelé, Louis Géli, Livio Ruffine, Carl A. Peters, and Tania Marsset
Subjects: 010504 meteorology & atmospheric sciences, Pockmark, Clathrate hydrate, Geochemistry, 15. Life on land, 010502 geochemistry & geophysics, 01 natural sciences, Seafloor spreading, chemistry.chemical_compound, Geophysics, Oceanography, chemistry, 13. Climate action, Geochemistry and Petrology, Transition zone, Anaerobic oxidation of methane, Carbonate, Submarine pipeline, Sedimentary rock, 14. Life underwater, Geology, 0105 earth and related environmental sciences
Abstract: The Niger Delta is one of the largest hydrocarbon basin offshore Africa and it is well known for the presence of active pockmarks on the seabed. During the Guineco-MeBo cruise in 2011, long cores were taken from a pockmark cluster in order to investigate the state of its current activity. Gas hydrates, oil and pore-water were sampled for geochemical studies. The resulting dataset combined with seismic data reveal that shallow hydrocarbon migration in the upper sedimentary section was focused exclusively within the pockmarks. There is a clear tendency for gas migration within the hydrate-bearing pockmarks, and oil migration within the carbonate-rich one. This trend is interpreted as a consequence of hydrate dissolution followed by carbonate precipitation in the course of the evolution of these pockmarks. We also demonstrate that Anaerobic Oxidation of Methane (AOM) is the main process responsible for the depletion of pore-water sulfate, with depths of the Sulfate-Methane Transition Zone (SMTZ) ranging between 1.8 and 33.4 m. In addition, a numerical transport-reaction model was used to estimate the age of hydrate-layer formation from the present-day sulfate profiles. The results show that the sampled hydrate-layers were formed between 21 and 3750 years before present. Overall, this work shows the importance of fluid flow on the dynamics of pockmarks, and the investigated cluster offers new opportunities for future cross-site comparison studies. Our results imply that sudden discharges of gas can create hydrate layers within the upper sedimentary column which can affect the seafloor morphology over few decades. This article is protected by copyright. All rights reserved.
Published: 2017
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14. Analysis of hydrogen and methane in seawater by 'Headspace' method: Determination at trace level with an automatic headspace sampler

Author: Jean-Pierre Donval and Vivien Guyader
Subjects: Detection limit, Chromatography, Hydrogen, 010401 analytical chemistry, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Headspace method, 021001 nanoscience & nanotechnology, 01 natural sciences, Nitrogen, Methane, 0104 chemical sciences, Analytical Chemistry, chemistry.chemical_compound, chemistry, Gas, 13. Climate action, Carbon dioxide, Seawater, Gas chromatography, 0210 nano-technology, Carbon monoxide
Abstract: “Headspace” technique is one of the methods for the onboard measurement of hydrogen (H2) and methane (CH4) in deep seawater. Based on the principle of an automatic headspace commercial sampler, a specific device has been developed to automatically inject gas samples from 300 ml syringes (gas phase in equilibrium with seawater). As valves, micro pump, oven and detector are independent, a gas chromatograph is not necessary allowing a reduction of the weight and dimensions of the analytical system. The different steps from seawater sampling to gas injection are described. Accuracy of the method is checked by a comparison with the “purge and trap” technique. The detection limit is estimated to 0.3 nM for hydrogen and 0.1 nM for methane which is close to the background value in deep seawater. It is also shown that this system can be used to analyze other gases such as Nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2) and light hydrocarbons.
Published: 2017
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15. Volcanic and hydrothermal processes in submarine calderas: the Kulo Lasi example (SW Pacific)

Author: Joel Etoubleau, Sandrine Cheron, Stéphanie Dupré, A.S. Alix, Vivien Guyader, Shasa Labanieh, Jean-Pierre Donval, Jean-Luc Charlou, Ewan Pelleter, Cecile Konn, Gilles Chazot, Yves Fouquet, Carla Scalabrin, Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre de Brest, Ingénierie des Matériaux Polymères - Laboratoire des Matériaux Polymères et des Biomatériaux (IMP-LMPB), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut de Chimie du CNRS (INC), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Ingénierie des Matériaux de Bretagne (LIMATB), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-Université de Brest (UBO), Allstat, Université Joseph Fourier - Grenoble 1 (UJF), and Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne)
Subjects: 010504 meteorology & atmospheric sciences, Lava, Geochemistry, Magma chamber, Sulfides, 010502 geochemistry & geophysics, 01 natural sciences, Hydrothermal circulation, Kulo Lasi caldera, Geochemistry and Petrology, Hydrothermal activity, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, 14. Life underwater, Subaqueous volcanism, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Geology, Seafloor spreading, Graben, Shield volcano, Volcano, Economic Geology, SW Pacific, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology
Abstract: 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 subduction that occurs 500 km to the east. The central caldera is 5 km in diameter and 300 m deep and is located at a water depth of 1500 m. Diving operations with the submersible Nautile and high-resolution AUV mapping, have revealed the presence of numerous active and inactive hydrothermal fields on the floor and the walls of the caldera. Four tectono-volcanic stages can be distinguished at Kulo Lasi caldera. In stage 1, the shield volcano is built. Annular reverse faults develop at the summit and control circulation of water/rock-dominated hydrothermal fluids and high-temperature alteration of rocks along the nascent normal faults. Mixing of hydrothermal fluids with seawater is favored along normal superficial faults, leading to the formation of low-temperature Fe/Mn mineralization at the summit of the volcano. During stage 2, the caldera collapse, gradually revealing outcrops of the altered and mineralized zones formed during Stage 1. As the magma chamber cools and collapses, less heat is available. As a result, medium to low-temperature (
Published: 2018
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16. Geochemistry

Author: Livio Ruffine, Sandrine Chéron, Emmanuel Ponzevera, Christophe Brandily, Patrice Woerther, Vivien Guyader, Audrey Boissier, Jean-Pierre Donval, and Germain Bayon
Published: 2018
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17. Living (stained) deep-sea foraminifera from the Sea of Marmara : a preliminary study

Author: François Baudin, Florence Savignac, Nicolas Gayet, Ewan Pelleter, Angélique Roubi, Delphine Dissard, Mathilde Pitel, Emmanuel Ponzevera, Audrey Boissier, Vivien Guyader, Briony Mamo, Françoise Lesongeur, S. Bermell-Fleury, Sandrine Cheron, Livio Ruffine, Christophe Fontanier, UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Variabilité à long terme du climat de l'océan (VALCO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Department of Biological Sciences [North Ryde], Macquarie University, Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Laboratoire de Géochimie et de Métallogénie, Institut des Sciences de la Terre de Paris (iSTeP), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire Géodynamique et enregistrement Sédimentaire - Geosciences Marines (GM-LGS), Laboratoire Environnement Profond (LEP), Laboratoire de microbiologie des environnements extrêmophiles (LM2E), Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), European program 'MARsite', under grant ENV.2012.6.4-2, Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Géosciences Marines (GM), Laboratoire Géochimie et Métallogénie (LGM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire Géodynamique et enregistrement Sédimentaire (LGS), and Etudes des Ecosystèmes Profonds (EEP)
Subjects: Sea of Marmara, Trace elements, 010504 meteorology & atmospheric sciences, biology, Stable isotope ratio, Living (stained) benthic foraminifera, Extreme ecosystems, 010502 geochemistry & geophysics, Oceanography, biology.organism_classification, 01 natural sciences, Deep sea, Cold seep, Foraminifera, Bottom water, chemistry.chemical_compound, chemistry, 13. Climate action, Carbonate, 14. Life underwater, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Stable isotopes
Abstract: International audience; In this preliminary study, we investigate living (stained) foraminifera from the Sea of Marmara. We focus on the faunal composition and geochemical signatures (trace elements, carbon and oxygen stable isotopes) in foraminiferal tests at two deep-sea sites (329 and ~ 1240 m depth respectively). Documented by ROV observations and sampling, both study areas are heterogeneous (including bacterial mats and carbonate concretions), proximal to cold seeps and consist of dysoxic bottom water (O2 < 20 µmol/L). The prevailing dysoxia at both study areas restricts foraminiferal diversity to very low values (S < 9, H’ < 0.97). Stress-tolerant species Bolivina vadescens and Globobulimina affinis dominate living faunas at both sites. The highest foraminiferal standing stock is recorded at the shallowest site underneath a spreading bacterial mat. No benthic foraminifera from either site possess geochemical signatures of methane seepage. Our biogeochemical results show that use of foraminiferal Mn/Ca ratios as a proxy for bottom water oxygenation depends strongly on regional physiography, sedimentary processes and water column structure.
Published: 2018
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18. Multidisciplinary investigation on cold seeps with vigorous gas emissions in the Sea of Marmara (MarsiteCruise): Strategy for site detection and sampling and first scientific outcome

Author: Claire Croguennec, Joel Etoubleau, Lucas Gasperini, Jean-Pierre Donval, Harald Strauss, Christian Podeur, Laurent Bignon, Christophe Fontanier, Ludovic Nicolas Legoix, Volkan Özaksoy, Emmanuel Rinnert, Davide Embriaco, Marie-Madeleine Blanc-Valleron, Jonathan Perchoc, Catherine Pierre, Carla Scalabrin, Pete Burnard, Delphine Dissard, Stéphanie Dupré, Bastien Thomas, Mathilde Pitel-Roudaut, M. Namık Çağatay, David Madre, Hélène Ondréas, Dominique Birot, Barbara M.A. Teichert, Eyyüp Özbeki, Yoan Germain, Céline Grall, Françoise Lesongeur, Emmanuel Ponzevera, Jean-Claude Caprais, Alina Polonia, Corinne Tarditi, Vivien Guyader, Pierre Henry, Hailong Lu, A.S. Alix, Louis Géli, Livio Ruffine, Hailin Yang, Nazli Olgun, Bernard Marty, Angélique Roubi, Joël Knoery, Nicolas Chevalier, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Westfälische Wilhelms-Universität Münster = University of Münster (WWU), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Lorraine (UL), Peking University [Beijing], Variabilité à long terme du climat de l'océan (VALCO), Istanbul Technical University (ITÜ), General Directorate of Mineral Research and Exploration, The Mineral Etude and Research Department, Ankara, Turkey 06520, Géosciences Marines (GM), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences et Environnement Cergy (GEC), Fédération INSTITUT DES MATÉRIAUX DE CERGY-PONTOISE (I-MAT), Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine, Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Istituto di Scienze Marine [Bologna] (ISMAR), Istituto di Science Marine (ISMAR ), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)-National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire de Recherche Impliquant la Géologie et la Mécanique (LIRIGM), Université Joseph Fourier - Grenoble 1 (UJF), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), European Project: 308417,EC:FP7:ENV,FP7-ENV-2012-two-stage,MARSITE(2012), Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Westfälische Wilhelms-Universität Münster (WWU), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Istanbul Technical University, Unité de recherche Géosciences Marines (Ifremer) (GM), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Consiglio Nazionale delle Ricerche (CNR)-Consiglio Nazionale delle Ricerche (CNR), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), ANR: 10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)
Subjects: Dissolved major elements, 010504 meteorology & atmospheric sciences, North Anatolian Fault, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Context (language use), 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Acoustic survey, Fluid seepage, Water column, 14. Life underwater, Chemical analyses, 0105 earth and related environmental sciences, Sediment, Geology, Authigenic, Biogeochemistry, In situ Raman analysis, Cold seep, Cold seeps, ROV dives, Authigenic carbonates, Methane, Petroleum seep, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental science, Seawater
Abstract: International audience; MarsiteCruise was undertaken in October/November 2014 in the Sea of Marmara to gain detailed insight into the fate of fluids migrating within the sedimentary column and partially released into the water column. The overall objective of the project was to achieve a more global understanding of cold-seep dynamics in the context of a major active strike-slip fault. Five remotely operated vehicle (ROV) dives were performed at selected areas along the North Anatolian Fault and inherited faults.To efficiently detect, select and sample the gas seeps, we applied an original procedure. It combines sequentially (1) the acquisition of ship-borne multibeam acoustic data from the water column prior to each dive to detect gas emission sites and to design the tracks of the ROV dives, (2) in situ and real-time Raman spectroscopy analysis of the gas stream, and (3) onboard determination of molecular and isotopic compositions of the collected gas bubbles. The in situ Raman spectroscopy was used as a decision-making tool to evaluate the need for continuing with the sampling of gases from the discovered seep, or to move to another one. Push cores were gathered to study buried carbonates and pore waters at the surficial sediment, while CTD-Rosette allowed collecting samples to measure dissolved-methane concentration within the water column followed by a comparison with measurements from samples collected with the submersible Nautile during the Marnaut cruise in 2007.Overall, the visited sites were characterized by a wide diversity of seeps. CO2- and oil-rich seeps were found at the westernmost part of the sea in the Tekirdag Basin, while amphipods, anemones and coral populated the sites visited at the easternmost part in the Cinarcik Basin. Methane-derived authigenic carbonates and bacterial mats were widespread on the seafloor at all sites with variable size and distributions. The measured methane concentrations in the water column were up to 377 μmol, and the dissolved pore-water profiles indicated the occurrence of sulfate depleting processes accompanied with carbonate precipitation. The pore-water profiles display evidence of biogeochemical transformations leading to the fast depletion of seawater sulfate within the first 25-cm depth of the sediment. These results show that the North Anatolian Fault and inherited faults are important migration paths for fluids for which a significant part is discharged into the water column, contributing to the increase of methane concentration at the bottom seawater and favoring the development of specific ecosystems.
Published: 2018
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19. Evidence and age estimation of mass wasting at the distal lobe of the Congo deep-sea fan

Author: Julie Le Bruchec, François Baudin, Jean-Claude Caprais, Germain Bayon, Christophe Brandily, Claire Croguennec, Christophe Rabouille, Claire Bollinger, Livio Ruffine, Vivien Guyader, Nathalie Babonneau, Laurence Droz, Bernard Dennielou, Yoan Germain, Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Evolution et Modélisation des Bassins Sédimentaires (EMBS), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnement Profond (LEP), Etudes des Ecosystèmes Profonds (EEP), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Océan et Interfaces (OCEANIS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Géosciences Marines (Ifremer) (GM), Département des Environnements Profonds, Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: chemistry.chemical_classification, Turbidity current, 010504 meteorology & atmospheric sciences, Sediment, Mass wasting, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Diagenesis, Sedimentary depositional environment, chemistry, 13. Climate action, Anaerobic oxidation of methane, [SDE]Environmental Sciences, Organic matter, Sedimentary rock, Geology, 0105 earth and related environmental sciences
Abstract: International audience; On continental margins, sulfate reduction occurs within the sedimentary column. It is coupled with the degradation of organic matter and the anaerobic oxidation of methane. These processes may be significantly disturbed by sedimentary events, leading to transient state profiles for the involved chemical species. Yet, little is known about the impact of turbidity currents and mass wasting on the migration of chemical species and the redox reactions in which they are involved. Due to its connection to the River, the Congo deep-sea fan continuously receives huge amount of organic matter-rich sediments primarily transported by turbidity currents, which impact on the development of the associated ecosystems (Rabouille et al., 2016). Thus, it is well suited to better understand causal relationships between sedimentary events and fluid flow path, with consequences on the zonation of early diagenesis sequences. Here, we combined sedimentological observations with geochemical analyses of pore-water and sediment samples to explore how sedimentary instabilities affected the migration of methane and the distribution of organic matter within the sedimentary column. The results unveiled mass wasting processes affecting recent turbiditic and pelagic deposits, and are interpreted as being slides/ slumps and debrites. Two slides were responsible for the exhumation of an organic matter-rich sedimentary block of more than 5 m thick and the movement of a methane-rich sedimentary block, while turbidity currents enable the intercalation of sandy intervals within a pelagic clay layer. The youngest slide promoted the development of two Sulfate Methane Transition Zones (SMTZ), and may have possibly triggered a lateral migration of methane. Numerical simulation of the sulfate profile indicates that the youngest sedimentary event has occurred around a century ago. Our study emphasizes that turbidity currents and sedimentary instabilities can significantly affect the transport paths and the distribution of both methane and organic matter in the terminal lobe complex, with consequences on geochemical zonation of the sequential early diagenetic processes within the sedimentary column.
Published: 2017
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20. Extensive hydrothermal activity revealed by multi-tracer survey in the Wallis and Futuna region (SW Pacific)

Author: Jean-Luc Charlou, Elise Fourré, Yves Fouquet, Ewan Pelleter, Cecile Konn, Jean-Pierre Donval, Philippe Jean-Baptiste, Florian Perez, A.S. Alix, Dominique Birot, Vivien Guyader, Arnaud Gaillot, Arnaud Dapoigny, Joseph A. Resing, Laboratoire Cycles Géochimiques et ressources (LCG), Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Allstat, Direction du Végétal et de l'Environnement, Agence Française de Sécurité Sanitaire des Aliments, Institut des Matériaux Jean Rouxel (IMN), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Critical Care Department, Hospital de Sabadell, CIBER Enfermedades Respiratorias, Géochrononologie Traceurs Archéométrie (GEOTRAC), Department of mathematics and computing science [Eindhoven], Eindhoven University of Technology [Eindhoven] (TU/e), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN), and Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne)
Subjects: Basalt, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Geochemistry, Transform fault, Mineralogy, Aquatic Science, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Hydrothermal circulation, Panoply, Plume, Tectonics, Volcano, 13. Climate action, Caldera, Seawater, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: The study area is close to the Wallis and Futuna Islands in the French EEZ. It exists on the western boundary of the fastest tectonic area in the world at the junction of the Lau and North-Fiji basins. At this place, the unstable back-arc accommodates the plate motion in three ways: (i) the north Fiji transform fault, (ii) numerous unstable spreading ridges, and (iii) large areas of recent volcanic activity. This instability creates bountiful opportunity for hydrothermal discharge to occur. Based on geochemical (CH 4 , TDM, 3 He) and geophysical (nephelometry) tracer surveys: (1) no hydrothermal activity could be found on the Futuna Spreading Centre (FSC) which sets the western limit of hydrothermal activity; (2) four distinct hydrothermal active areas were identified: Kulo Lasi Caldera, Amanaki Volcano, Fatu Kapa and Tasi Tulo areas; (3) extensive and diverse hydrothermal manifestations were observed and especially a 2D distribution of the sources. At Kulo Lasi, our data and especially tracer ratios (CH 4 / 3 He ~50×10 6 and CH 4 /TDM ~4.5) reveal a transient CH 4 input, with elevated levels of CH 4 measured in 2010, that had vanished in 2011, most likely caused by an eruptive magmatic event. By contrast at Amanaki, vertical tracer profiles and tracer ratios point to typical seawater/basalt interactions. Fatu Kapa is characterised by a substantial spatial variability of the hydrothermal water column anomalies, most likely due to widespread focused and diffuse hydrothermal discharge in the area. In the Tasi Tulo zone, the hydrothermal signal is characterised by a total lack of turbidity, although other tracer anomalies are in the same range as in nearby Fatu Kapa. The background data set revealed the presence of a Mn and 3 He chronic plume due to the extensive and cumulative venting over the entire area. To that respect, we believe that the joined domain composed of our active area and the nearby active area discovered in the East by Lupton et al. (2012) highly contribute to the extensive Tonga-Fiji plume and which thus may not originate from a sole source near the Samoa. Our results also emphasize and support the idea that back-arc hydrothermal systems have a significant input to the regional and global ocean and maybe more important than their MOR analogues.
Published: 2016
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21. Multi Scales Exploration Strategy - Example of Research For Hydrothermal Mineralization in the French EEZ of Wallis and Futuna

Author: M. Guillou, X. Saint-Laurent, J. Dyment, Florent Szitcar, A.S. Alix, Vivien Guyader, Carla Scalabrin, Charline Guerin, D. Pierre, Jean-Pierre Donval, Stéphanie Dupré, Ewan Pelleter, F. Rosazza, Cecile Konn, Yves Fouquet, and M. Patriat
Subjects: chemistry.chemical_classification, Mineralization (geology), Sulfide, chemistry, Hydrothermal mineralization, Geochemistry, Hydrothermal circulation, Geology
Abstract: As part of a Public Private consortium, explorations to locate sulfide mineralization in the French EEZ of Wallis and Futuna allowed to discover new hydrothermal fields. Three cruises organized between 2010 and 2012 have explored this area. The first phase focused on a regional mapping to find areas of recent volcanism using multibeam echosounders and acoustic imaging. Hydrothermal plumes produced by high temperature hydrothermal activity were located using chemical and physical anomalies in the water column. Using a CTD/rosette we collected water samples and measured physical parameters. Onboard methane and manganese concentrations and physical parameters studies helped to locate active fields with a precision of about 5 km. Physical anomalies caused by the hydrothermal plumes were also recorded by analyzing the multibeam backscattered signals of the water column. In a second phase, an AUV, operated at 70m above the seafloor, helped to establish high-resolution (1 m) bathymetric maps on targets identified during Phase 1. Near seafloor, magnetic anomalies were recorded using a deep magnetometer on the AUV. Analysis of AUV acoustic signals in the water column allowed to find the vertical part of the hydrothermal plumes and to pinpoint areas of fluids discharge with a precision of a few meters. During the third phase, manned submersible dives were conducted on the hydrothermal fields to study the hydrothermal fluids, the different types of mineralization and associated ecosystems. This multi-scale strategy allows gaining considerable time in exploration, and led to the discovery of several hundred of active and inactive fields and associated sulfides mineralization on an area not previously mapped. The AUV high-resolution mapping and detection of vertical plumes and inactive chimneys can thus be considered as a missing link of the exploration strategy to locate hydrothermal deposits.
Published: 2015
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22. Continuous exhumation of mantle-derived rocks at the Southwest Indian Ridge for 11 million years

Author: Christopher J. MacLeod, Julie Carlut, A. Bronner, Mathilde Cannat, Vivien Guyader, Roger Searle, Etienne Ruellan, Muriel Andreani, Daniel Sauter, Dominique Birot, Daniele Brunelli, Adélie Delacour, Véronique Mendel, Gianreto Manatschal, Stéphane Rouméjon, Valerio Pasini, Bénédicte Ménez, Ecole et Observatoire des Sciences de la Terre (EOST), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Dynamique de la lithosphère et des bassins sédimentaires (IPGS) (IPGS-Dylbas), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Dipartimento di Scienze della Terra [Modena], Università degli Studi di Modena e Reggio Emilia (UNIMORE), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), School of Earth and Ocean Sciences [Cardiff], Cardiff University, Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences [Durham], Durham University, Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Géosciences Marines (GM), Università degli Studi di Modena e Reggio Emilia = University of Modena and Reggio Emilia (UNIMORE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Volcanism, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Paleontology, Lithosphere, 14. Life underwater, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Plate tectonics, Tectonics, Ridge push, Volcano, 13. Climate action, Ridge, South West Indian Ridge, amagmatic spreading, mantle peridotite, smooth seafloor, slow spreading ridge, General Earth and Planetary Sciences, Seismology, Geology
Abstract: The global mid-ocean ridge system, where tectonic plates diverge, is traditionally thought of as the largest single volcanic feature on the Earth. Yet, wide expanses of smooth sea floor in the easternmost part of the Southwest Indian Ridge in the Indian Ocean lacks the hummocky morphology that is typical for submarine volcanism. At other slow-spreading ridges, the sea floor can extend by faulting the existing lithosphere, along only one side of the ridge axis. However, the smooth sea floor in the easternmost Southwest Indian Ridge also lacks the corrugated texture created by such faulting. Instead, the sea floor is smooth on both sides of the ridge axis and is thought to be composed of altered mantle-derived rocks. Here we use side-scan sonar to image the sea floor and dredge samples to analyse the composition of two sections of the Southwest Indian Ridge, between 62 degrees 05'E and 64 degrees 40'E, where the sea floor formed over the past 11 million years. We show that the smooth floor is almost entirely composed of seawater-altered mantle-derived rocks that were brought to the surface by large detachment faults on both sides of the ridge axis. Faulting accommodates almost 100% of plate divergence and the detachment faults have repeatedly flipped polarity. We suggest that this tectonic process could also explain the exhumation of mantle-derived rocks at the magma-poor margins of rifted continents.
Published: 2013
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23. Geochemical Dynamics of the Natural-Gas Hydrate System in the Sea of Marmara, Offshore Turkey

Author: Sandrine Cheron, Yoan Germain, Vivien Guyader, Çagatay M. Namik, Céline Grall, Olivia Fandiño, Bortoluzzi Giovanni, Pierre Henry, Giuseppe Etiope, Luca Gasperini, Livio Ruffine, Emmanuel Ponzevera, Géli Louis, Joel Etoubleau, Charlou Jean-Luc, Bernard Dennielou, and Jean-Pierre Donval
Subjects: chemistry.chemical_classification, 010504 meteorology & atmospheric sciences, business.industry, Clathrate hydrate, Geochemistry, 010502 geochemistry & geophysics, Permafrost, 01 natural sciences, Methane, chemistry.chemical_compound, Hydrocarbon, Oceanography, chemistry, 13. Climate action, Propane, Natural gas, Carbon dioxide, Hydrate, business, Geology, 0105 earth and related environmental sciences
Abstract: Natural-gas hydrate systems are solid-state light-hydrocarbon accumulations which are encountered in the permafrost and the continental margins. They are stable under highpressure and low-temperature conditions and represent the major hydrocarbon volume on earth (Kvenvolden, 1988). Gas hydrates consist of a polycrystalline structure where a light hydrocarbon is trapped within a water lattice. The nature of the hydrocarbons is strongly related to their origin which is either microbial (also called biogenic) or thermogenic. Microbial gas-hydrate systems contain hydrocarbons produced by bacteria and archaea. There are primarily methane with a very small amount of ethane and eventually propane (Max, 2003). Others non-hydrocarbon compounds like hydrogen sulphur and carbon dioxide are also present. In the case of microbial gases, the hydrates are formed at or near the gas production area. Owing to the very high-methane content, these hydrates are commonly called methane-hydrate systems.
Published: 2012

24. Geochemical Dynamics of the Natural-Gas Hydrate System in the Sea of Marmara, Offshore Turkey

Author: Livio Ruffine, Olivia Fandino, Joël Etoubleau, Sandrine Chéron, Jean-Pierre Donval, Yoan Germain, Emmanuel Ponzevera, Vivien Guyader, Bernard Dennielou, Giuseppe Etiope, Luca Gasperini, Bortoluzzi Giovanni, Pierre Henry, Céline Grall, Çagatay M. Namik, Charlou Jean-Luc, Géli Louis, Livio Ruffine, Olivia Fandino, Joël Etoubleau, Sandrine Chéron, Jean-Pierre Donval, Yoan Germain, Emmanuel Ponzevera, Vivien Guyader, Bernard Dennielou, Giuseppe Etiope, Luca Gasperini, Bortoluzzi Giovanni, Pierre Henry, Céline Grall, Çagatay M. Namik, Charlou Jean-Luc, and Géli Louis
Published: 2012
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24 results on '"Vivien Guyader"'

1. Active hydrothermal vents in the Woodlark Basin may act as dispersing centres for hydrothermal fauna

2. Hydrothermal plumes as hotspots for deep-ocean heterotrophic microbial biomass production

3. Inter-Comparison of the Spatial Distribution of Methane in the Water Column From Seafloor Emissions at Two Sites in the Western Black Sea Using a Multi-Technique Approach

4. Processes Driving Iron and Manganese Dispersal From the TAG Hydrothermal Plume (Mid-Atlantic Ridge): Results From a GEOTRACES Process Study

5. Extending the dataset of fluid geochemistry of the Menez Gwen, Lucky Strike, Rainbow, TAG and Snake Pit hydrothermal vent fields: Investigation of temporal stability and organic contribution

6. A GC-SSIM-CRDS System: Coupling a Gas Chromatograph with a Cavity Ring-Down Spectrometer for Onboard Twofold Analysis of Molecular and Isotopic Compositions of Natural Gases during Ocean-Going Research Expeditions

7. Birth of a large volcanic edifice offshore Mayotte via lithosphere-scale dyke intrusion

8. Birth of a large volcanic edifice through lithosphere-scale dyking offshore Mayotte (Indian Ocean)

9. Effects of postglacial seawater intrusion on sediment geochemical characteristics in the Romanian sector of the Black Sea

10. A simple method for the preparation and injection of gas mixtures into a gas chromatograph using a two-component device

11. Measuring methane from the seafloor to the atmosphere: an integrated experiment in the Black Sea

12. Birth of a large volcanic edifice offshore Mayotte (Comoros Island, Western Indian Ocean)

13. Focused hydrocarbon-migration in shallow sediments of a pockmark cluster in the Niger Delta (Off Nigeria)

14. Analysis of hydrogen and methane in seawater by 'Headspace' method: Determination at trace level with an automatic headspace sampler

15. Volcanic and hydrothermal processes in submarine calderas: the Kulo Lasi example (SW Pacific)

16. Geochemistry

17. Living (stained) deep-sea foraminifera from the Sea of Marmara : a preliminary study

18. Multidisciplinary investigation on cold seeps with vigorous gas emissions in the Sea of Marmara (MarsiteCruise): Strategy for site detection and sampling and first scientific outcome

19. Evidence and age estimation of mass wasting at the distal lobe of the Congo deep-sea fan

20. Extensive hydrothermal activity revealed by multi-tracer survey in the Wallis and Futuna region (SW Pacific)

21. Multi Scales Exploration Strategy - Example of Research For Hydrothermal Mineralization in the French EEZ of Wallis and Futuna

22. Continuous exhumation of mantle-derived rocks at the Southwest Indian Ridge for 11 million years

23. Geochemical Dynamics of the Natural-Gas Hydrate System in the Sea of Marmara, Offshore Turkey

24. Geochemical Dynamics of the Natural-Gas Hydrate System in the Sea of Marmara, Offshore Turkey

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