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Registros recuperados: 20
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Behaviour of rare earth and trace elements during fluid venting at cold seeps ArchiMer
Birot, Dominique; Bayon, Germain; Ruffine, Livio; Caprais, Jean-claude; Bollinger, C.; Ponzevera, Emmanuel; Rongemaille, Emmanuelle; Voisset, Michel.
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00023/13414/10493.pdf
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Campagne HYDROFAST: Etudes quantitatives de l'activité hydrothermale sur la Ride-Est Pacifique à 13°N ArchiMer
Bougault, Henri; Appriou, P; Birolleau, A; Charlou, Jean-luc; Crane, K; Etoubleau, Joel; Fouquet, Yves; Gente, P; Harmegnies, Francois; Landure, Jean-yves; Le Noac'H, A; Pelle, Henri; Sichler, Bertrand; Voisset, Michel; Watremez, Pierre; Vaslet, N; Jean Baptiste, P.
Tipo: Text
Ano: 1990 URL: http://archimer.ifremer.fr/doc/00070/18104/15652.pdf
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Constraints on the dynamic of gas hydrates in Niger Delta sediments from U/Th dating of cold-seep carbonates ArchiMer
Henderson, Gm; Bayon, Germain; Pierre, C; Caprais, Jean-claude; Voisset, Michel.
Tipo: Text
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3587.pdf
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Detection of free gas and gas hydrate based on 3D seismic data and cone penetration testing: An example from the Nigerian Continental Slope ArchiMer
Sultan, Nabil; Voisset, Michel; Marsset, Tania; Vernant, Antoine-mathieu; Cauquil, E; Colliat, J; Curinier, V.
We present a new method to characterize free gas, gas hydrates and carbonate concretions occurrence which are considered as high-risk factors for sub-sea developments in the Niger delta. This method is based on the combination of 3D seismic data to the geotechnical site characterizations using piezocone CPTU tests (Cone Penetration Test with additional measurement of the pore water pressure). A special processing of the 3D seismic data has enabled the determination of the interval compressional velocity. Using the effective-medium theory, velocity anomalies (negative and positive) within the first 15 m were translated in gas hydrate and free gas distribution. The calibration of the P wave velocity anomalies was done thanks to in-situ geotechnical testing...
Tipo: Text Palavras-chave: Piezocone; Niger delta; Gas hydrate; Free gas; Effective medium theory.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2610.pdf
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Dynamics of fault-fluid-hydrate system around a shale-cored anticline in deepwater Nigeria ArchiMer
Sultan, Nabil; Riboulot, Vincent; Ker, Stephan; Marsset, Bruno; Geli, Louis; Tary, Jean-baptiste; Klingelhoefer, Frauke; Voisset, Michel; Lanfumey, Valentine; Colliat, Jean-louis; Adamy, Jerome; Grimaud, S..
Gas hydrates were recovered by coring at the eastern border of a shale-cored anticline in the eastern Niger Delta. To characterize the link between faults and fluid release and to identify the role of fluid flow in the gas hydrate dynamics, three piezometers were deployed for periods ranging from 387 to 435 days. Two of them were deployed along a major fault linked to a shallow hydrocarbon reservoir while the third monitored the fluid pressure in a pockmark aligned above the same major fault. In addition, 10 ocean-bottom seismometers (OBS) were deployed for around 60 days. The piezometers simultaneously registered a prolonged fluid flow event lasting 90 days. During this time, OBS measurements record several episodic fluid release events. By combining and...
Tipo: Text
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00060/17106/14624.pdf
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Evidence for intense REE scavenging at cold seeps from the Niger Delta margin ArchiMer
Bayon, Germain; Birot, Dominique; Ruffine, Livio; Caprais, Jean-claude; Ponzevera, Emmanuel; Bollinger, C.; Donval, Jean-pierre; Charlou, Jean-luc; Voisset, Michel; Grimaud, S..
For many trace elements, continental margins are the location of intense exchange processes between sediment and seawater, which control their distribution in the water column, but have yet to be fully understood. In this study, we have investigated the impact of fluid seepage at cold seeps on the marine cycle of neodymium. We determined dissolved and total dissolvable (TD) concentrations for REE and well-established tracers of fluid seepage (CH4, TDFe, TDMn), and Nd isotopic compositions in seawater samples collected above cold seeps and a reference site (i.e. away from any fluid venting area) from the Niger Delta margin. We also analyzed cold seep authigenic phases and various core-top sediment fractions (pore water, detrital component, easily leachable...
Tipo: Text Palavras-chave: Rare earth elements; Neodymium isotopes; Seawater; Cold seeps; Fe-Mn oxyhydroxides; Benthic fluxes.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00066/17754/15571.pdf
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Hf and Nd isotope records of West African monsoon precipitation in sediments from the Niger Delta ArchiMer
Bayon, Germain; Etoubleau, Joel; Ponzevera, Emmanuel; Voisset, Michel.
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00023/13413/10490.pdf
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High resolution seafloor images in the Gulf of Cadiz, Iberian margin ArchiMer
Hanquiez, V; Mulder, T; Lecroart, P; Gonthier, E; Marches, E; Voisset, Michel.
In the Gulf of Cadiz, the hydrodynamic process acting on particle transport and deposition is a strong density-driven bottom current caused by the outflow of the saline deep Mediterranean water at the Strait of Gibraltar: the Mediterranean Outflow Water (MOW). New high resolution acoustic data including EM300 multibeam echo-sounder, deep-towed acoustic system SAR and very high resolution seismic, completed by piston cores collected during the CADISAR cruise allow to improve the understanding of the hydrodynamics of the MOW in the eastern part of the Gulf of Cadiz. Interpretation of data corrects the previous model established in this area and allows, for the first time, the accurate characterization of various bedforms and erosive structures along the MOW...
Tipo: Text Palavras-chave: Instabilities; Sedimentary processes; Acoustic facies; Deep towed SAR; Contourites; Mediterranean Outflow Water MOW; Gulf of Cadiz.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-3676.pdf
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High-resolution seismic imaging in deep sea from a joint deep-towed/OBH reflection experiment: application to a Mass Transport Complex offshore Nigeria ArchiMer
Ker, Stephan; Marsset, Bruno; Garziglia, Sebastien; Le Gonidec, Y.; Gibert, D.; Voisset, Michel; Adamy, J..
P>We assess the feasibility of high-resolution seismic depth imaging in deep water based on a new geophysical approach involving the joint use of a deep-towed seismic device (SYSIF) and ocean bottom hydrophones (OBHs). Source signature measurement enables signature deconvolution to be used to improve the vertical resolution and signal-to-noise ratio. The source signature was also used to precisely determine direct traveltimes that were inverted to relocate source and receiver positions. The very high accuracy of the positioning that was obtained enabled depth imaging and a stack of the OBH data to be performed. The determination of the P-wave velocity distribution was realized by the adaptation of an iterative focusing approach to the specific...
Tipo: Text Palavras-chave: Controlled source seismology; Seismic tomography; Acoustic properties; Submarine landslides; Atlantic Ocean.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00044/15510/12959.pdf
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Hydrate dissolution as a potential mechanism for pockmark formation in the Niger delta ArchiMer
Sultan, Nabil; Marsset, Bruno; Ker, Stephan; Marsset, Tania; Voisset, Michel; Vernant, Antoine-mathieu; Bayon, Germain; Cauquil, Eric; Adamy, J.; Colliat, J. L.; Drapeau, D..
Based on acquired geophysical, geological and geotechnical data and modeling, we suggest hydrate dissolution to cause sediment collapse and pockmark formation in the Niger delta. Very high-resolution bathymetry data acquired from the Niger delta reveal the morphology of pockmarks with different shapes and sizes going from a small ring depression surrounding an irregular floor to more typical pockmarks with uniform depression. Geophysical data, in situ piezocone measurements, piezometer measurements and sediment cores demonstrate the presence of a common internal architecture of the studied pockmarks: inner sediments rich in gas hydrates surrounded by overpressured sediments. The temperature, pressure and salinity conditions of the studied area have allowed...
Tipo: Text Palavras-chave: Methane gas hydrate; Sea floor; Marine sediments; Pore pressure; Porous media; Continental margin; Clathrate hydrate; Fluid flow; Stability; Slope.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00012/12300/9092.pdf
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Identification of Shear Zones and Their Causal Mechanisms Using a Combination of Cone Penetration Tests and Seismic Data in the Eastern Niger Delta ArchiMer
Garziglia, Sebastien; Sultan, Nabil; Cattaneo, Antonio; Ker, Stephan; Marsset, Bruno; Riboulot, Vincent; Voisset, Michel; Adamy, J.; Unterseh,.
In a site investigation of the eastern part of the offshore Niger delta, cone penetration tests (CPTU) showed significant drops in tip resistance, associated with decreases in sleeve friction and induced excess pore pressures at the interface between superficial sediments and the underlying deposits of a mass-transport complex (MTC) called NG1. Such signature characteristics of weakened zones are clearly expressed at three sites where the drop in tip resistance reaches more than 40% over 2-3 m-thick intervals. Correlations between CPTU profiles and both 3D and ultrahigh-resolution 2D seismic data suggest that the weakened zones surround syndepositional the within the frontal part of NG1. Hence, weakening appears associated with the remobilization of thrust...
Tipo: Text Palavras-chave: Cone penetration tests; Shear zone; 3D seismic data; Ultrahigh-resolution 2D seismic; Mass-transport complex; Slope stability.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00105/21662/19695.pdf
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Investigation on the geochemical dynamics of a hydrate-bearing pockmark in the Niger Delta ArchiMer
Ruffine, Livio; Caprais, Jean-claude; Bayon, Germain; Riboulot, Vincent; Donval, Jean-pierre; Etoubleau, Joel; Birot, Dominique; Pignet, Patricia; Rongemaille, Emmanuelle; Chazallon, Bertrand; Grimaud, Sylvie; Adamy, Jerome; Charlou, Jean-luc; Voisset, Michel.
A joint industrial project with IFREMER and Total provides insights into the tectonic setting and the geochemistry of a large active pockmark offshore W-Africa in the Niger Delta. The study combines both geophysical (seismic) and geochemical data to infer the dynamics of a 300 m wide pockmark located at 667 m water depth. Two Calypso cores, one at the centre and one outside the pockmark, along with three box-cores, two inside the pockmark and one outside, were collected to study the geochemistry of gas hydrates, carbonates and pore waters. Two seismic lines, a 3D high resolution random line and a 2D high resolution seismic line, provide a good description of the plumbing of the system. The integrated results depict a very active pockmark characterized by...
Tipo: Text Palavras-chave: Active pockmark; Anaerobic oxidation of methane; Gas hydrates; Carbonates; Seismic surveys; Fault system; U/Th dating.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00139/24981/23102.pdf
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Past deep-ocean circulation and the paleoclimate record-Gulf of Cadiz ArchiMer
Mulder, T.; Lecroart, T. P.; Voisset, Michel; Schönfeld, J.; Le Drezen, Eliane; Gonthier, E.; Hanquiez, Vincent; Zahn, R.; Faugères, J.-c.; Hernandez-molina, F. J.; Llave-barranco, E.; Gervais, Anne.
Deep marine currents are strongly influenced by climatic changes. They also deposit, rework, and sort sediment, and can generate kilometer-scale sedimentary bodies (drifts). These drifts are made of thoroughly bioturbated, stacked sedimentary sequences called contourites [Gonthier et al., 1984]. As a consequence, change in the direction or intensity of currents can be recorded in the sediments.
Tipo: Text
Ano: 2002 URL: http://archimer.ifremer.fr/doc/00210/32143/30600.pdf
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Post-glacial persistence of turbiditic activity within the Rhone deep-sea turbidite system (Gulf of Lions, Western Mediterranean): Linking the outer shelf and the basin sedimentary records ArchiMer
Dennielou, Bernard; Jallet, Laurent; Sultan, Nabil; Jouet, Gwenael; Giresse, Pierre; Voisset, Michel; Berne, Serge.
Emplacement of post-glacial turbidites is commonly controlled by rapid changes in sea level or by seismicity. On the continental rise of the Gulf of Lions (Western Mediterranean), an aseismic area, we identified turbiditic beds deposited during the rising stage and highstand of sea level. Swath bathymetry, sediment cores, in situ Cone Penetrating Tests (CPTU), heavy mineral associations and radiocarbon dating determined the source, composition, distribution and age of the turbiditic beds. Turbidites are composed of homogeneous to positively graded silts to medium sand with quartz (up to 90%), shell debris and shelfal benthic faunas. Their distribution on the sea floor is very patchy and controlled by abundant inherited erosional bedforms. Their source is...
Tipo: Text Palavras-chave: Holocene; Late Pleistocene; Sea level; Turbidites; Sand; Outer shelf; Canyons.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6316.pdf
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Potential role of compressional structures in generating submarine slope failures in the Niger Delta ArchiMer
Sultan, Nabil; Voisset, Michel; Marsset, Bruno; Marsset, Tania; Cauquil, E; Colliat, J.
The study area, offshore Nigeria, is located in one of the compressional zones within the Niger Delta, which is characterized by imbricate thrust structures. Although the low mean slope angle (around 2°), bathymetry data from the study area have shown the existence of several submarine landslides which coincide with known subsurface faulted compressive features. In this paper, we have focused on a submarine slide occurring in water depths ranging between 1690 and 1750 m. Headwall scars, internal architecture and associated deposits have been characterized using a combination of 3D seismic data, near-bottom echosounder seismic profiles, Kullenberg cores and in-situ geotechnical measurements. The slide shows horseshoe shaped headwall scars and depositional...
Tipo: Text Palavras-chave: Slope stability; Piezometer; Penetrometer; Niger Delta; Modelling; Compressional structures.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2408.pdf
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Premières observations sur la morphologie et les processus sédimentaires récents de l'Éventail celtique ArchiMer
Auffret, Gérard-andré; Zaragosi, S; Voisset, Michel; Droz, Laurence; Loubrieu, Benoit; Pelleau, Pascal; Savoye, R; Bourillet, Jean-francois; Baltzer, Agness; Bourquin, S; Dennielou, Bernard; Coutelle, Alain; Weber, N; Floch, Gilbert.
During the SEDIFAN 1 cruise we surveyed the bathymetry and the acoustic properties of the surface sediment of the Celtic Deep Sea Fan. We also collected Kullenberg cores in order to study recent sedimentary processes. From the bathymetry survey it is relatively easy to recognize the main areas of modern fan. The upper fan included a large sedimentary ridge which constitutes the right levee of the prominent meandering Whittard valley. After its confluence with the Shamrock valley the course of the Whittard valley is abruptly deflected to the south. At a short distance to the south the valley divides into two upper-fan channels, the Celtic channel to the west being the deeper one. This point constitutes the centre of a radiating pattern which is developed on...
Tipo: Text Palavras-chave: Paléoclimat; Turbidité; Sédiment; Quaternaire; Eventail profond; Palaeoclimate; Turbidity; Sediment; Quaternary; Deep sea fan.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/2000/publication-525.pdf
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Sea-level change and free gas occurrence influencing a submarine landslide and pockmark formation and distribution in deepwater Nigeria ArchiMer
Riboulot, Vincent; Cattaneo, Antonio; Sultan, Nabil; Garziglia, Sebastien; Ker, Stephan; Imbert, Patrice; Voisset, Michel.
A series of pockmarks observed at the seabed matches well the perimeter of a large submarine landslide, called NG1, located on the outer shelf and continental slope of the Eastern Gulf of Guinea. NG1 extends over 200 km2, is covered by a 120-m thick sedimentary layer which tapers downslope, and has an internal structure clearly identified in 3D seismic data consisting of three adjacent units on the upper continental slope. The pockmarks above NG1 have a diameter of several tens of meters and reveal distinct origins: (1) linked to >500 m deep fluid reservoirs, (2) rooted in NG1 internal discontinuities between NG1 units, and (3) well above NG1, superficially rooted in a regional conformity (D40), which marks the lowest sea level of the Marine Isotope...
Tipo: Text Palavras-chave: Pockmarks; Fluid seepage; Submarine landslide; Sea-level changes; Piezocone; Niger Delta.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00159/27031/31906.pdf
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Sr/Ca and Mg/Ca ratios in Niger Delta sediments: Implications for authigenic carbonate genesis in cold seep environments ArchiMer
Bayon, Germain; Pierre, C; Etoubleau, Joel; Voisset, Michel; Cauquil, E; Marsset, Tania; Sultan, Nabil; Le Drezen, Eliane; Fouquet, Yves.
We report on a reconnaissance analysis of the geochemical composition of authigenic carbonates and sediment samples collected from various seepage sites on the Niger deep-sea fan. Our aim has been to investigate whether evidence for the presence of authigenic carbonates and gas hydrates within sediments is discernible from solid-phase sediment geochemistry. We show that sedimentary Sr/Ca and Mg/Ca ratios can be used to infer the presence of authigenic aragonite (Sr-rich) and Mg-rich carbonate phases (high-Mg calcite, dolomite) in cold seep settings. Using Sr/Ca and Mg/Ca ratios, the proportion (wt.%) of authigenic carbonates in Niger Fan sediments can be calculated from a mixing model between sediment fractions of terrigenous material, biogenic calcite,...
Tipo: Text Palavras-chave: Niger Delta; Gas hydrates; Cold seeps; Mg/Ca; Sr/Ca; Authigenic carbonates.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2696.pdf
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The western part of the Gulf of Cadiz: contour currents and turbidity currents interactions ArchiMer
Mulder, Thierry; Lecroart, P; Hanquiez, V; Marches, E; Gonthier, E; Guedes, J; Thiebot, E; Jaaidi, B; Kenyon, N; Voisset, Michel; Perez, C; Sayago, M; Fuchey, Y; Bujan, S.
Recent multibeam bathymetry and acoustic imagery data provide a new understanding of the morphology of the western part of the Gulf of Cadiz. The gulf is under the influence of a strong current, the Mediterranean Outflow Water (MOW). This current is at the origin of the construction of the giant Contourite Depositional System. Canyons and valleys with erosive flanks are observed. Only the Portimao Canyon is presently connected to the continental shelf. Channels occur on the continental shelf but are presently disconnected from the deeper network of channels and valleys. Slumps are localized in steep slope areas. They are caused by oversteepening and overloading, sometimes probably associated with earthquake activity. Slumps transform sharply into turbidity...
Tipo: Text Palavras-chave: Contour current; Interaction; Turbidity current; Geomorphology; Gulf of Cadiz.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1718.pdf
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U-Th isotope constraints on gas hydrate and pockmark dynamics at the Niger delta margin ArchiMer
Bayon, Germain; Henderson, Gideon M.; Etoubleau, Joel; Caprais, Jean-claude; Ruffine, Livio; Marsset, Tania; Dennielou, Bernard; Cauquil, Eric; Voisset, Michel; Sultan, Nabil.
The application of uranium-thorium dating methods to authigenic carbonates provides unique constraints on the temporal evolution of methane seeps at ocean margins. In this study, we report U-Th isotope measurements for carbonate breccias collected from within a hydrate-bearing pockmark located at the Niger Delta margin. These concretions were extracted from a carbonate-rich layer in the upper two meters of a sediment core (N2-KS-44; ~ 1200 m water depth), well above the present-day sulphate-methane transition zone (about 3 m depth) and the presence of gas hydrates in the sediment. The stratigraphy of core N2-KS-44 was established by tuning its downcore Al/Ti profile to a well-dated nearby reference core, and carbonate 230Th/U ages were calculated using...
Tipo: Text Palavras-chave: Gas hydrates; Pockmarks; U-series; Authigenic carbonates; Niger delta.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00286/39708/41518.pdf
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