Consulta: creatorFacets:"Foucher, Jean-paul"
Registros recuperados: 29
Data/hora: 08/06/2024 10:45:20

The ocean-continent transition in the uniform lithospheric stretching model : role of partial melting in the mantle
Provedor de dados: 5
Autores: Foucher, Jean-paul; Le Pichon, Xavier; Sibuet, Jean-claude.
The role of partial melting in the uniform lithospheric stretching model of continental margin formation is explored.  It is shown that the transition from continental lithosphere stretching to oceanic accretion is most probably controlled by the production of a significant amount of partial melting in the asthenosphere immediately below the lithosphere, which requires stretching factors larger than 3.  It is also shown that, at stretching factors exceeding 2, the law of subsidence is significantly changed by the presence of partial melt in the underlying asthenosphere.  The implications for the existence of deep continental margin basins on thinned continental crusts are examined. The Armorican deep continental margin basin is taken as an example. [NOT...
Tipo: Text
Palavras-chave: Histoire Ifremer.
Ano: 1981
URL: http://archimer.ifremer.fr/doc/1981/publication-5375.pdf

First results of a geophysical survey on the northern flank of the Storegga. slides (Norway).
Provedor de dados: 5
Autores: Nouze, Herve; Contrucci, Isabelle; Foucher, Jean-paul; Marsset, Bruno; Thomas, Yannick; Thereau, Estelle; Normand, Alain; Le Drezen, Eliane; Didailler, Stephane; Regnault, Jean-pierre; Le Conte, Sandie; Guidart, Stéphanie; Lekens, Win; Dean, Simon; Throo, Alexandre.
The Storegga slides, off Norway, are among the largest submarine slides ever known on a continental slope. The HYDRATECH cruise on N/O Le Suro (i) over capt aimed at a high-resolution survey of an area at the northern boundary of the slides. This survey images in great detail the bottom simulating reflector (BSR) extent and properties, the various fluid escape structures and the sediment deformations. The combination and the quality of the data help to understand the still poorly constrained relationships between fluid escapes, gas hydrates and slope stability in the survey area.
Tipo: Text
Palavras-chave: Slope stability; Fluid escapes; Gas hydrates; Storegga.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-511.pdf

Effect of gas hydrates melting on seafloor slope instability
Provedor de dados: 5
Autores: Sultan, Nabil; Cochonat, Pierre; Foucher, Jean-paul; Mienert, J.
We present a theoretical study of the thermodynamic chemical equilibrium of gas hydrate in soil by taking into account the influence of temperature, pressure, pore water chemistry, and the mean pore size distribution. The model uses a new formulation based on the enthalpy form of the law of conservation of energy. The developed model shows that due to a temperature and pressure increase, hydrates may dissociate at the top of the hydrate occurrence zone to ensure a chemical equilibrium with the surrounding bulk water. This original result confirms what has been already shown through experiments. The second part of the paper presents an application of the model through a back-analysis of the giant Storegga Slide on the Norwegian margin. Two of the most...
Tipo: Text
Palavras-chave: Storegga; Slope failure; GLE; Finite difference; Methane hydrate.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-699.pdf

Changes in seabed morphology, mud temperature and free gas venting at the Håkon Mosby mud volcano, offshore northern Norway, over the time period 2003-2006
Provedor de dados: 5
Autores: Foucher, Jean-paul; Dupre, Stephanie; Scalabrin, Carla; Feseker, Tomas; Harmegnies, Francois; Nouze, Herve.
The Håkon Mosby mud volcano is a 1.5-km-diameter geological structure located on the Southwest Barents Sea slope at a water depth of 1,270 m. High-definition seabed mapping of the mud volcano has been carried out in 2003 and 2006. A comparative analysis of the bathymetry and backscatter maps produced from the two surveys shows subtle morphological changes over the entire crater of the mud volcano, interpreted to be the consequence of mud eruption events. Mud temperature measurements point to a persistently warm mud at shallow depth in the crater. This is explained by upward fluid advection, rather than conductive cooling of mud flows. The small-scale spatial variability in the temperature distribution may be related to mud outflows or changes in the fluid...
Tipo: Text
Palavras-chave: Sw barents sea; Cold seep ecosystems; Fluid flow; Methane; Sediment; Onshore; Fluxes; Margin; Water.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00004/11527/10261.pdf

AUV surveys cold seep sites on the Nile fan
Provedor de dados: 5
Autores: Boetius, Antje; Buffet, G; Mascle, Jean; Dupre, Stephanie; Foucher, Jean-paul.
Tipo: Text
Ano: 2007
URL: http://archimer.ifremer.fr/doc/00185/29669/28041.pdf

From intracratonic extension to mature spreading in back arc basins: Examples from the Okinawa, Lau, North Fiji basins
Provedor de dados: 5
Autores: Auzende, Jean-marie; Boespflug, Xavier; Bougault, Henri; Dosso, Laure; Foucher, Jean-paul; Joron, Jean-louis; Ruellan, Etienne; Sibuet, Jean-claude.
Three cruises (POP 1, SEAPSO 3 and SEAPSO 4) carried out during the "Tour du Monde" of the R.V. Jean Charcot allow us to obtain new structural and geochemical data for the Okinawa, North Fiji and Lau basins. Taken together, the structural and geochemical data illustrate a difference in evolution stages of these sites. The less evolved stage is represented by the Okinawa basin, where accretion is evidenced only by volcanic intrusion into a thinned continental crust. The most evolved stage is illustrated in the North Fiji basin, where the present-day accretion can be directly compm·ed to the East Pacific Ridge. The Lau basin displays an intem1ediate stage with a complex system of accretionary ridges. This difference in the evolution stage is translated in...
Tipo: Text
Palavras-chave: Ouest Pacifique; Bassins arriere arc; Structure; Accretion; Geochimie; West Pacific; Back arc basins; Structure; Accretion; Geochemistry.
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00119/23058/20893.pdf

Thermal regime of the northern bay of biscay continental margin in the vicinity of DSDP sites 400 to 402
Provedor de dados: 5
Autores: Sibuet, Jean-claude; Foucher, Jean-paul.
Ten conventional oceanic surface heat flow measurements were made over the northern margin of the Bay of Biscay in the vicinity of the DSDP Sites 400 to 402 during the R/V Suroit - SU 01 (December 1975) and R/v Jean Charcot - CH 66 (February 1976) cruises of CNEXO. These measurements, complemented by the heat flow determination made at Site 402 during Leg 48 of the Deep Sea Drilling Project (Erickson et al; this volume) provide information on the thermal regime of the margin.The main observation is that the regional heat flux over the margin is substantially lower than over the adjacent Western European continental area.We suggest in this report that the observed heat flux contrast provides constraints on the debatable nature of the crustal thinning...
Tipo: Text
Palavras-chave: Histoire Ifremer.
Ano: 1979
URL: http://archimer.ifremer.fr/doc/1979/publication-5279.pdf

High-resolution mapping of large gas emitting mud volcanoes on the Egyptian continental margin (Nile Deep Sea Fan) by AUV surveys
Provedor de dados: 5
Autores: Dupre, Stephanie; Buffet, G.; Mascle, J.; Foucher, Jean-paul; Gauger, S.; Boetius, A.; Marfia, Christian.
Two highly active mud volcanoes located in 990-1,265 m water depths were mapped on the northern Egyptian continental slope during the BIONIL expedition of R/V Meteor in October 2006. High-resolution swath bathymetry and backscatter imagery were acquired with an autonomous underwater vehicle (AUV)-mounted multibeam echosounder, operating at a frequency of 200 kHz. Data allowed for the construction of similar to 1 m pixel bathymetry and backscatter maps. The newly produced maps provide details of the seabed morphology and texture, and insights into the formation of the two mud volcanoes. They also contain key indicators on the distribution of seepage and its tectonic control. The acquisition of high-resolution seafloor bathymetry and acoustic imagery maps...
Tipo: Text
Palavras-chave: Eastern Mediterranean; Seafloor morphology; Backscatter; Bathymetry; AUV; Nile Deep Sea Fan; Mud volcanoes.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6395.pdf

Menes caldera, a highly active site of brine seepage in the Eastern Mediterranean sea: "In situ" observations from the NAUTINIL expedition (2003)
Provedor de dados: 5
Autores: 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

Multi-disciplinary investigation of fluid seepage on an unstable margin: The case of the Central Nile deep sea fan
Provedor de dados: 5
Autores: 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

Multi-scale seafloor mapping of active seep-related structures, offshore Egypt
Provedor de dados: 5
Autores: Dupre, Stéphanie; Woodside, John; Klaucke, Ingo; Mascle, Jean; Foucher, Jean-paul.
The Nile deep sea fan system presents a rich variety of fluid escape structures, gas chimneys, pockmarks and carbonate crust mounds, brines pools, and several types of mud volcano. These seep-related structures were explored for the first time with the Nautile submersible during the 2003 Nautinil expedition and are characterized by high thermal gradients and highly gas-saturated sediments. More recently, high resolution side scan sonar data acquired during the 2004 Mimes expedition brings more detail to the geophysical imagery. The EdgeTech DTS-1 deep tow sonar coupled with a 2-8 kHz chirp subbottom penetrator was deployed around 100 m above the seafloor and operated at a frequency of 75 kHz. Several gas plumes were acoustically detected in the water...
Tipo: Text
Palavras-chave: Free gas emission; Backscatter; Authigenic carbonate crust; Mud volcanism; Gas chimneys; Nile Deep Sea Fan.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2005/acte-6396.pdf

Dynamics of gas hydrate: case of the Congo continental slope
Provedor de dados: 5
Autores: Sultan, Nabil; Foucher, Jean-paul; Cochonat, Pierre; Tonnerre, T; Bourillet, Jean-francois; Ondreas, Helene; Cauquil, E; Grauls, D.
A numerical model is developed to study the temperature effect on stability and phase transformation of gas-hydrate. The model uses a mathematical formulation based on the enthalpy form of the conservation law of energy. The use of the enthalpy form instead of the temperature form as often done in the literature has made the problem numerically simpler. The model is then applied to describe the effect of sea bottom temperature variations on the stability of gas hydrate occurrences and on the seafloor reflectivity in sediments of the Congo continental slope. Indeed, a migrating seafloor reflectivity front is observed on 3D seimic images from two surveys performed 6 months apart and interpreted as a migrating gas hydrate stability zone. Seawater temperature...
Tipo: Text
Palavras-chave: Temperature; Stefan problem; Seafloor reflectivity; Gas hydrate; Heat flow; Finite difference; Continental margins.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-702.pdf

Comments on 'Thermal Effects of the Formation of Atlantic Continental Margins by Continental Break up' by N.H. Sleep
Provedor de dados: 5
Autores: Foucher, Jean-paul; Le Pichon, Xavier.
Sleep (1971) has presented some very interesting observations on the exponential decrease of the subsidence rate in coastal basins. He shows that the time constant of this exponential decrease is of the same order of magnitude that the thermal time constant of a lithospheric plate. He then makes calculations with a physical model combining erosion and thermal contraction. The purpose of these comments is to show that his physical assumptions are invalid and that çonsequently his calculations are grossly in error. [NOT CONTROLLED OCR]
Tipo: Text
Palavras-chave: Histoire Ifremer.
Ano: 1972
URL: http://archimer.ifremer.fr/doc/1972/publication-5041.pdf

56. Morphology and Basement Structures of the Goban Spur Continental Margin (Northeastern Atlantic) and the Role of the Pyrenean Orogeny
Provedor de dados: 5
Autores: Sibuet, Jean-claude; Mathis, B; Pastouret, Léo; Auzende, Jean-marie; Foucher, Jean-paul; Hunter, Peter; Guennoc, P; De Graciansky, Pc; Montadert, L; Masson, Douglas.
Tipo: Text
Ano: 1985
URL: http://archimer.ifremer.fr/doc/00184/29494/27815.pdf

Estimating mud expulsion rates from temperature measurements on Hakon Mosby Mud Volcano, SW Barents Sea
Provedor de dados: 5
Autores: Kaul, Norbert; Foucher, Jean-paul; Heesemann, M.
The HAkon Mosby Mud Volcano (HMMV), located on the Norwegian-Barents-Svalbard continental margin in 1250 m water depth, has been identified and described as a structure caused by upward transport of mud, pore water and gas [e.g. Eldhohn, O., Sundvor, E., Vogt, P.R., Hjelstuen, B.O., Crane, K., Nilsen, A.K., Gladczenko, T.P., 1999. SW Barents Sea continental margin heat flow and HAkon Mosby Volcano. Geo-Marine Letters 19, 29-37]. During R V Polarstern expedition ARK XIX/3b in 2003, an integrated study took place to investigate the detailed morphology, biology, chemistry and geophysical aspects of HMMV [Kiages, M., Thiede, J., Foucher, J.-P., 2004. The Expeditions ARK XIX 3a, 3b and 3c, Berichte zur Polarforschung, 488.]. In this paper, we describe a...
Tipo: Text
Palavras-chave: SW Barents Sea; Convection; Heat flow; Mud volcano; Seafloor hydrothermal system.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-2002.pdf

Widespread active seepage activity on the Nile Deep Sea Fan (offshore Egypt) revealed by high-definition geophysical imagery
Provedor de dados: 5
Autores: Dupre, Stephanie; Woodside, John; Klaucke, Ingo; Mascle, Jean; Foucher, Jean-paul.
Fluid escape structures on the Nile Deep Sea Fan were investigated during the MEDIFLUX MIMES expedition in 2004. Mud volcanoes, pockmarks and authigenic carbonate structures were surveyed for the first time with a high-resolution deep-towed 75 kHz sidescan sonar and a 2-8 kHz Chirp sediment echosounder. In combination with existing multibeam bathymetry and detailed seafloor in situ geological observations, these new data allowed detailed seep analyses. About 60 gas flares were detected acoustically in the water column from the sidescan sonar raw data at water depths from 770 to 1700 m. These gas flares coincide at the seabed with 1) the centres of the mud volcanoes where mud is also extruded, 2) the borders of the mud volcanoes where the emitted gases...
Tipo: Text
Palavras-chave: Nile Deep Sea Fan; Seepage; Backscatter; Sidescan sonar; High-resolution; Gas chimneys; Mud volcanoes; Authigenic carbonates.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00013/12457/9766.pdf

Warm brine lakes in craters of active mud volcanoes, Menes caldera off NW Egypt: evidence for deep-rooted thermogenic processes
Provedor de dados: 5
Autores: Dupre, Stephanie; Mascle, Jean; Foucher, Jean-paul; Harmegnies, Francois; Woodside, John; Pierre, Catherine.
The Menes caldera is a fault-controlled depression (~8 km in diameter) at ~3,000 m water depth in the western province of the Nile deep-sea fan off NW Egypt, comprising seven mud volcanoes (MVs) of which two are active. Based on multichannel and chirp seismic data, temperature profiles, and high-resolution bathymetric data collected during the 2000 Fanil, 2004 Mimes and 2007 Medeco2 expeditions, the present study investigates factors controlling MV morphology, the geometry of feeder channels, and the origin of emitted fluids. The active Cheops and Chephren MVs are 1,500 m wide with subcircular craters at their summits, about 250 m in diameter, generally a few tens of metres deep, and filled with methane-rich muddy brines with temperatures reaching 42 °C...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00185/29668/28151.pdf

Biogeochemistry and community composition of iron- and sulfur-precipitating microbial mats at the Chefren mud volcano (Nile Deep Sea fan, Eastern Mediterranean)
Provedor de dados: 5
Autores: Omoregie, E; Mastalerz, V; De Lange, G; Straub, K; Kappler, A; Roy, H; Stadnitskaia, A; Foucher, Jean-paul; Boetius, A.
In this study we determined the composition and biogeochemistry of novel, brightly colored, white and orange microbial mats at the surface of a brine seep at the outer rim of the Chefren mud volcano. These mats were interspersed with one another, but their underlying sediment biogeochemistries differed considerably. Microscopy revealed that the white mats were granules composed of elemental S filaments, similar to those produced by the sulfide-oxidizing epsilonproteobacterium "Candidatus Arcobacter sulfidicus." Fluorescence in situ hybridization indicated that microorganisms targeted by a "Ca. Arcobacter sulfidicus"-specific oligonucleotide probe constituted up to 24% of the total the cells within these mats. Several 16S rRNA gene sequences from organisms...
Tipo: Text
Palavras-chave: Gulf of mexico; Sulfate reducing bacteria; Egyptian continental margin; Northeast pacific ocean; Ribosomal rna sequences; In situ hybridization; Anaerobic oxidation; Marine sediments; Gas hydrate; Oxiding bacteria.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6201.pdf

Novel microbial communities of the Haakon Mosby mud volcano and their role as a methane sink
Provedor de dados: 5
Autores: Niemann, H; Losekann, T; De Beer, D; Elvert, M; Nadalig, T; Knittel, K; Amann, R; Sauter, E; Schluter, M; Klages, M; Foucher, Jean-paul; Boetius, A.
Mud volcanism is an important natural source of the greenhouse gas methane to the hydrosphere and atmosphere(1,2). Recent investigations show that the number of active submarine mud volcanoes might be much higher than anticipated ( for example, see refs 3 - 5), and that gas emitted from deep-sea seeps might reach the upper mixed ocean(6-8). Unfortunately, global methane emission from active submarine mud volcanoes cannot be quantified because their number and gas release are unknown(9). It is also unclear how efficiently methane-oxidizing microorganisms remove methane. Here we investigate the methane-emitting Haakon Mosby Mud Volcano (HMMV, Barents Sea, 72 degrees N, 14 degrees 44' E; 1,250 m water depth) to provide quantitative estimates of the in situ...
Tipo: Text
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-4514.pdf

Geophysical characterization of bottom simulating reflectors in the Fairway Basin (off New Caledonia, Southwest Pacific), based on high resolution seismic profiles and heat flow data
Provedor de dados: 5
Autores: Nouze, Herve; Cosquer, Emmanuel; Collot, Julien; Foucher, Jean-paul; Klingelhoefer, Frauke; Lafoy, Yves; Geli, Louis.
High-resolution reflection and refraction seismic data were collected in 2004 to investigate, in further detail than allowed by pre-existing low resolution seismic data, the nature of a Bottom Simulating Reflector (BSR) that extends over a broad area of the Fairway Basin, a rifted, continental structure located on the eastern flank of the Lord Howe Rise, to the southwest of New Caledonia. Two main reflectors are documented: the shallower (RN) mimics the seafloor and has a negative polarity while the deeper (RP) does not always mimic the seafloor and has a positive polarity. Using the existing regional seismic lines, we can show that reflector RN can be continuously followed up to DSDP 208 drill hole site. Reflector RP is discontinuous and cannot be traced...
Tipo: Text
Palavras-chave: Stratigraphy; Gas hydrates; Geophysics; Southwest Pacific; Fairway Basin; BSR.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-7321.pdf

Structure and Drivers of Cold Seep Ecosystems
Provedor de dados: 5
Autores: Foucher, Jean-paul; Westbrook, Graham K.; Boetius, Antje; Ceramicola, Silvia; Dupre, Stephanie; Mascle, Jean; Mienert, Jurgen; Pfannkuche, Olaf; Pierre, Catherine; Praeg, Daniel.
Submarine hydrocarbon seeps are geologically driven "hotspots" of increased biological activity on the seabed. As part of the HERMES project, several sites of natural hydrocarbon seepage in the European seas were investigated in detail, including mud volcanoes and pockmarks, in study areas extending from the Nordic margin, to the Gulf of Cadiz, to the Mediterranean and Black seas. High-resolution seabed maps and the main properties of key seep sites are presented here. Individual seeps show ecosystem zonation related to the strength of the methane flux and distinct biogeochemical processes in surface sediments. A feature common to many seeps is the formation of authigenic carbonate constructions. These constructions exhibit various morphologies ranging...
Tipo: Text
Palavras-chave: Mosby mud volcano; Deep sea fan; Eastern mediterranean sea; Black sea; Anaerobic oxidation; Hydrocarbon seeps; Carbonate crusts; Sidescan sonar; Hydrate ridge; Gas chimneys.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6387.pdf

From intracratonic extension to nature spreading in back arc basins: Examples from the Okinawa, Lau and, North Fiji basins
Provedor de dados: 5
Autores: Auzende, Jean Marie; Boespflug, X; Bougault, Henri; Dosso, Laure; Foucher, Jean-paul; Joron, J-l; Ruellan, Etienne; Sibuet, Jean-claude.
Three cruises (POP 1, SEAPSO 3 and SEAPSO 4) carried out during the "Tour du Monde" of the R.V. Jean Charcot allow us to obtain new structural and geochemical data for the Okinawa, North Fiji and Lau basins. Taken together, the structural and geochemical data illustrate a difference in evolution stages of these sites. The less evolved stage is represented by the Okinawa basin, where accretion is evidence only by volcanic intrusion into a thinned continental crust. The most evolved stage is illustrated in the North Fiji basin, where the present-day accretion can be directly compared to the East Pacific Ridge. The Lau basin displays an intermediate stage with a complex system of accretionary ridges. This difference in the evolution stage is translated in the...
Tipo: Text
Ano: 1990
URL: http://archimer.ifremer.fr/doc/00268/37893/35974.pdf

Microbial methane oxidation and sulfate reduction at cold seeps of the deep Eastern Mediterranean Sea
Provedor de dados: 5
Autores: Omoregie, Enoma O.; Niemann, Helge; Mastalerz, Vincent; De Lange, Gert J.; Stadnitskaia, Alina; Mascle, Jean; Foucher, Jean-paul; Boetius, Antje.
The Eastern Mediterranean hosts a variety of active cold seep systems, such as gas chimneys, mud volcanoes and pockmarks, in water depths of 500 to 3200 m. As part of the NAUTINIL expedition in 2003, the sediments of cold seeps on the Nile Deep Sea Fan (NDSF) were sampled for the first time for biogeochemical and microbiological analyses. Here we compare rates of the anaerobic oxidation of methane (AOM) and sulfate reduction (SR) as well as the microbial community structure of a variety of cold seep systems including mud volcanoes, pockmarks and brine seeps. Our results revealed strong differences in microbial activity among the different seep systems of the Eastern, Central and Western provinces of the NDSF, as well as the Olimpi field (Central...
Tipo: Text
Palavras-chave: Methane oxidation; Sulfate reduction; Archaea; Cold seeps; Mud volcano; Pockmarks; Nile Deep Sea Fan.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00000/11087/7910.pdf

Methane discharge from a deep-sea submarine mud volcano into the upper water column by gas hydrate-coated methane bubbles
Provedor de dados: 5
Autores: Sauter, Eberhard; Muyakshin, Sergey; Charlou, Jean-luc; Schluter, Michael; Boetius, Antje; Jerosch, Kerstin; Damm, Ellen; Foucher, Jean-paul; Klages, Michael.
The assessment of climate change factors includes a constraint of methane sources and sinks. Although marine geological Sources are recognized as significant, unfortunately, most submarine sources remain poorly quantified. Beside cold vents and coastal anoxic sediments, the large number of submarine mud volcanoes (SMV) may contribute significantly to the oceanic methane pool. Recent research suggests that methane primarily released diff-usively from deep-sea SMVs is immediately oxidized and, thus, has little climatic impact.   New hydro-acoustic, Visual, and geochemical observations performed at the deep-sea mud volcano Hakon Mosby reveal the discharge of gas hydrate-coated methane bubbles and gas hydrate flakes forming huge methane plumes extending from...
Tipo: Text
Palavras-chave: Hydro acoustics; Gas hydrates; Gas bubbles; Submarine mud volcanoes; Methane budget; Plume; Methane sources.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1345.pdf

Seafloor geological studies above active gas chimneys off Egypt (Central nile deep sea fan)
Provedor de dados: 5
Autores: Dupre, Stephanie; Woodside, J; Foucher, Jean-paul; De Lange, G; Mascle, J; Boetius, A; Mastalerz, V; Stadnitskaia, A; Ondreas, Helene; Huguen, C; Harmegnies, Francois; Gontharet, Swanne; Loncke, L; Deville, E; Niemann, H; Omoregie, E; Olu, Karine; Fiala Medioni, A; Dahlmann, A; Caprais, Jean-claude; Prinzhofer, A; Sibuet, Myriam; Pierre, C; Damste, J.
Four mud volcanoes of several kilometres diameter named Amon, Osiris, Isis, and North Alex and located above gas chimneys on the Central Nile Deep Sea Fan, were investigated for the first time with the submersible Nautile. One of the objectives was to characterize the seafloor morphology and the seepage activity across the mud volcanoes. The seepage activity was dominated by emissions of methane and heavier hydrocarbons associated with a major thermal contribution. The most active parts of the mud volcanoes were highly gas-saturated (methane concentrations in the water and in the sediments, respectively, of several hundreds of nmol/L and several mmol/L of wet sediment) and associated with significantly high thermal gradients (at 10 m below the seafloor,...
Tipo: Text
Palavras-chave: Seafloor morphology; Methane; Authigenic carbonate precipitation; Gas chimneys; Mud breccia; Mud volcanoes; Fluid seepage; Nile fan.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-4455.pdf

Images may show start of European-African plate collision
Provedor de dados: 5
Autores: Mascle, J.; Huguen, C.; Benkhelil, J.; Chamot-rooke, N.; Chaumillon, E.; Foucher, Jean-paul; Griboulard, R.; Kopf, A.; Lamarche, G.; Volkonskaia, A.; Woodside, J.; Zitter, T.
Aspects of the initial stages of a collision between European and African plates may have been documented in a geophysical survey of the central Mediterranean Ridge (MR) conducted last year. The idea of an incipient collision was first suggested by Finetti [1976],and details of the seafloor and tectonic deformation along the MR, revealed for the first time in the survey, seem to point in that direction. A unique opportunity may therefore exist for studying the beginnings of such a collision—between the passive margin of a major plate (Africa) acting as a continental indenter against the active margin of another plate (Europe). More wide angle data, deep penetrating multichannel seismic data, and drilling data are crucial to better assess the nature and the...
Tipo: Text
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00451/56252/57823.pdf

Estimation of gas hydrate concentration from multi-component seismic data at sites on the continental margins of NW Svalbard and the Storegga region of Norway
Provedor de dados: 5
Autores: Westbrook, G; Chand, S; Rossi, G; Long, C; Bunz, S; Camerlenghi, A; Carcione, J; Dean, S; Foucher, Jean-paul; Flueh, E; Gei, D; Haacke, R; Madrussani, G; Mienert, Jurgen; Minshull, T; Nouze, Herve; Peacock, S; Reston, T; Vanneste, M; Zillmer, M.
High-resolution seismic experiments, employing arrays of closely spaced, four-component ocean-bottom seismic recorders, were conducted at a site off western Svalbard and a site on the northern margin of the Storegga slide, off Norway to investigate how well seismic data can be used to determine the concentration of methane hydrate beneath the seabed. Data from P-waves and from S-waves generated by P-S conversion on reflection were inverted for P- and S-wave velocity (V-p and V-s), using 3D travel-time tomography, 2D ray-tracing inversion and 1D waveform inversion. At the NW Svalbard site, positive V-p anomalies above a sea-bottom-simulating reflector (BSR) indicate the presence of gas hydrate. A zone containing free gas up to 150-m thick, lying immediately...
Tipo: Text
Palavras-chave: Continental margin; Hydrate concentration; Seismic velocity; S wave; P wave.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6122.pdf

Thermal history of deep-sea sediments as a record of recent changes in the deep circulation of the eastern Mediterranean
Provedor de dados: 5
Autores: Della Vedova, B; Pellis, G; Camerlenghi, A; Foucher, Jean-paul; Harmegnies, Francois.
[1] During three cruises of the MEDRIFF project in 1993 and 1994, 154 geothermal heat flow measurements and seven CTD profiles in the water column have been collected along a 300 km SW-NE oriented transect traversing the Mediterranean Ridge accretionary complex. The original goal of the measurements was to identify areas of anomalous heat flow that could be interpreted as possible sites for fluid outflow. Contrary to expectations, the upper few meters of the temperature profiles in the sediments showed decreasing temperature from the seafloor down to 3 to 6 m depth indicating consistently transient temperature regimes. The only exception ( positive heat flow) was found in the Sirte abyssal plain. Measurements collected in the same area at different times...
Tipo: Text
Palavras-chave: Eastern Mediterranean; Aegean waters; Sediment warming; Heat flow measurements; Thermal modeling; Thermal history.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00000/10675/9319.pdf

Variations in heat flow across the Goban Spur and Galicia Bank continental margins
Provedor de dados: 5
Autores: Louden, K. E; Sibuet, Jean-claude; Foucher, Jean-paul.
We present the results of 44 new heat flow stations which were taken in 1984 and 1989 in profiles across the Goban Spur and Galicia Bank continental margins (NW Atlantic Ocean). Simple extensional models indicate that the heat flow across both these Early Cretaceous rifted margins should increase from values of 45-50 mW/m2 over oceanic crust to 65-80 mW/m2 on the continents. The rate of this increase should help to constrain the mechanism (simple versus pure shear) by which the upper, more radiogenic continental crust is thinned. Measurements across Goban Spur increase from values of 40-45 mW/m2 over oceanic crust to 50-55 mW/m2 near the continental shelf. They follow the predicted trend for pure-shear rifting, but only if the value of upper crustal...
Tipo: Text
Ano: 1991
URL: http://archimer.ifremer.fr/doc/00182/29341/28269.pdf