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16 results on '"Etoubleau, Joel"'

1. 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

Ruffine, Livio, Ondreas, Hélène, Blanc-Valleron, Marie-Madeleine, Teichert, Barbara M.A., Scalabrin, Carla, Rinnert, Emmanuel, Birot, Dominique, Croguennec, Claire, Ponzevera, Emmanuel, Pierre, Catherine, Donval, Jean-Pierre, Alix, Anne-Sophie, Germain, Yoan, Bignon, Laurent, Etoubleau, Joel, Caprais, Jean-Claude, Knoery, Joel, Lesongeur, Françoise, Thomas, Bastien, Roubi, Angélique, Legoix, Ludovic Nicolas, Burnard, Pete, Chevalier, Nicolas, Lu, Hailong, Dupré, Stéphanie, Fontanier, Christophe, Dissard, Delphine, Olgun, Nazli, Yang, Hailin, Strauss, Harald, Özaksoy, Volkan, Perchoc, Jonathan, Podeur, Christian, Tarditi, Corinne, Özbeki, Eyyüp, Guyader, Vivien, Marty, Bernard, Madre, David, Pitel-Roudaut, Mathilde, Grall, Céline, Embriaco, Davide, Polonia, Alina, Gasperini, Lucas, Çağatay, M. Namik, Henry, Pierre, and Géli, Louis

Published
2018
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4. Evolution of the Pacific-Antarctic Ridge South of the Udintsev Fracture Zone

Author

Géli, Louis, Bougault, Henri, Aslanian, Daniel, Briais, Anne, Dosso, Laure, Etoubleau, Joël, Le Formal, Jean-Pierre, Maia, Marcia, Ondréas, Hélène, Olivet, Jean-Louis, Richardson, Chris, Sayanagi, Keizo, Seama, Nobukazu, Shah, Anjana, Vlastelic, Ivan, and Yamamoto, Michiko

Published
1997

10. The control of weathering processes on riverine and seawater hafnium isotope ratios

Author

Bayon, Germain, Vigier, Nathalie, Burton, Kevin W., Brenot, Agnes, Carignan, Jean, Etoubleau, Joel, and Chu, Nan-Chin

Subjects
Geology -- Research, Shields (Geology) -- Research, Earth sciences
Abstract

Hafnium [sup.176]Hf/[sup.177]Hf isotope ratio variations in marine records are thought to reflect changes in continental weathering through time, but the behavior of Hf in rivers, and during weathering, is not well understood. Here, we present [sup.176]Hf/[sup.177]Hf data for rivers, bedrock, soils, and leaching experiments for the Moselle basin, Vosges, France. These data strongly suggest that the [sup.176]Hf/[sup.177]Hf composition of river waters is controlled by preferential dissolution of accessory phases (i.e., apatite, sphene) versus more resistant minerals (e.g., K-feldspar) and linked to the intensity of silicate weathering. Estimates for the global isotopic composition of riverine Hf suggest that the ocean Hf budget may be dominated by river input, and variations seen in marine records can be directly related to changes in silicate weathering intensity. Keywords: hafnium isotopes, rivers, silicate weathering, ocean chemistry.

Published
2006

12. Chemical systematics of an intermediate spreading ridge: The Pacific-Antarctic Ridge between 56 degrees S and 66 degrees S

Author

Vlastelic, Ivan, Dosso, Laure, Bougault, Henri, Daniel Aslanian, Louis Géli, Etoubleau, Joel, Bohn, Marcel, JORON JL, and Bollinger, C.

Abstract

Axial bathymetry, major/trace elements, and isotopes suggest:that the Pacific-Antarctic Ridge (PAR) between 56 degrees S and 66 degrees S is devoid of any hotspot influence. PAR (56-66 degrees 5) samples have in-average lower Sr-87/Sr-86 and Nd-143/Nd-144 and higher Pb-206/(204)pb than northern Pacific midocean ridge basalts (MORB), and also than MORE from the other oceans. The high variability of Pb isotopic ratios (compared to Sr and Nd) can be due to either a;general high mu (HIMU) (high U/Pb) affinity of the southern Pacific upper mantle or to a mantle event first recorded in time by Pb isotopes. Compiling the results of this study with those from the PAR between 53 degrees S and 57 degrees S gives a continuous view of mantle characteristics from south Pitman Fracture Zone (FZ) to Vacquier FZ, representing about 3000 km of spreading axis. The latitude of Udintsev FZ (56 degrees S) is a limit between, to the north, a domain with large geochemical Variations and, to the south, one with small Variations. The spreading rate has intermediate values (54 mm/yr at 66 degrees S to 74 mm/yr at 56 degrees S) which increase along the PAR, while the axial morphology: changes from valley to dome. The morphological transition is not recorded by the chemical properties of the ridge basalts nor by the inferred mantle temperature which displays few variations (30-40 degrees C) along the PAR. Contrary to what is observed along the South-East Indian Ridge, PAR morphology appears to be controlled more by spreading rate rather than by mantle temperature. Much of the major and trace element variability results from segmentation control on the shallowest thermal structure of the mantle. The cold edge of a fracture zone seems to be more efficient when occurring in an axial dome context.:It is expressed as an increase of the magnitude of the Transform Fault Effect along the valley-dome transition, resulting in a clear increase of trace element ratio variability (such as Nb/Zr). There is no strong evidence for the previously proposed southwestward asthenospheric flow in the area. However, this flow model could explain the intrasegment asymmetric patterns.

Published
2000

16. Investigation on the geochemical dynamics of a hydrate-bearing pockmark in the Niger Delta.

Author

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, Jérome, Charlou, Jean-Luc, and Voisset, Michel

Subjects
*GEOCHEMISTRY, *HYDRATES, *STRUCTURAL geology, *GEOPHYSICS, *CARBONATES
Abstract

Abstract: 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 several gas charged-bodies, a well identified BSR marking a hydrate accumulation zone, charged from deeper sources via a network of faults. Hydrates and carbonate concretions have been detected inside the pockmark while only the latter has been found outside. The hydrate analyses show that the hydrate-forming gases are of thermogenic origin, albeit overwhelmingly composed of methane. Pore-water analyses reveal the occurrence of anaerobic oxidation of methane coupled with sulphate reduction at shallow depth (∼200 cm). The chloride concentration profile exhibits both values lower than that of seawater which is inherent to hydrate dissociation after core recovery and positive anomalies (values 7% higher than that of seawater background) at the lowermost part of the core. The latter evidence suggests current or recent hydrate formation at this area. The carbonate dating provides additional temporal information and indicates that this pockmark has been active since ∼21 kyr. [Copyright &y& Elsevier]

Published
2013
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