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Registros recuperados: 6
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Authigenic carbonate mounds from active methane seeps on the southern Aquitaine Shelf (Bay of Biscay, France): evidence for anaerobic oxidation of biogenic methane and submarine groundwater discharge during formation ArchiMer
Pierre, Catherine; Demange, Jerome; Blanc-valleron, Marie-madeleine; Dupre, Stephanie.
The widespread methane emissions that were discovered in 2013 on the Aquitaine Shelf at water depth between 140 and 220 m are associated with authigenic carbonate crusts that cover meter-high subcircular reliefs of 10 to 100 m in diameter. These authigenic carbonates are primarily aragonite plus calcite and dolomite, which cement the fine- to medium-grained sandy sediment. The carbonate cement is often pierced by numerous circular cavities of 5 to 10 µm in diameter that are considered to be moulds of gas bubbles. Conversely, micron-sized cavities in the aragonite crystals are attributed to dissolution features, in relation to the production of CO2 during the aerobic oxidation of methane. The oxygen isotopic compositions of bulk carbonate (+1.7 to +3.7‰)...
Tipo: Text Palavras-chave: Aquitaine Shelf; Methane-derived authigenic carbonates; Oxygen isotopes; Carbon isotopes; Submarine groundwater discharge; Anaerobic oxidation of methane; Aerobic oxidation of methane.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00361/47209/47164.pdf
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Authigenic carbonates related to active seepage of methane-rich hot brines at the Cheops mud volcano, Menes caldera (Nile deep-sea fan, eastern Mediterranean Sea) ArchiMer
Pierre, Catherine; Bayon, Germain; Blanc-valleron, Marie-madeleine; Mascle, Jean; Dupre, Stephanie.
On the passive margin of the Nile deep-sea fan, the active Cheops mud volcano (MV; ca. 1,500 m diameter, ~20–30 m above seafloor, 3,010–3,020 m water depth) comprises a crater lake with hot (up to ca. 42 °C) methane-rich muddy brines in places overflowing down the MV flanks. During the Medeco2 cruise in fall 2007, ROV dives enabled detailed sampling of the brine fluid, bottom lake sediments at ca. 450 m lake depth, sub-surface sediments from the MV flanks, and carbonate crusts at the MV foot. Based on mineralogical, elemental and stable isotope analyses, this study aims at exploring the origin of the brine fluid and the key biogeochemical processes controlling the formation of these deep-sea authigenic carbonates. In addition to their patchy occurrence in...
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Ano: 2014 URL: http://archimer.ifremer.fr/doc/00186/29735/28189.pdf
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Diagenetic modulation of the magnetic properties in sediments from the Northern Indian Ocean ArchiMer
Bouilloux, Alexandra; Valet, Jean-pierre; Bassinot, Franck; Joron, Jean-louis; Blanc-valleron, Marie-madeleine; Moreno, Eva; Dewilde, Fabien; Kars, Myriam; Lagroix, France.
Large changes in magnetic mineral concentration dependent parameters by more than 1 order of magnitude occur over 50-150 cm intervals in two marine sediment cores from the oxygen minimum zone in the Gulf of Aden. High-resolution sedimentological and chemical analyses indicate that these intervals are not associated with turbiditic events or sediment reworking, they do not result from changes in carbonate dilution or differences in sediment properties, and they do not correspond to volcanic layers. Magnetic mineralogical analyses reveal a change in magnetic mineral concentration from a magnetite-goethite assemblage to pure magnetite within the peak. The peaks almost disappear when the abundance of magnetic minerals is calculated after correcting for the...
Tipo: Text Palavras-chave: Paleomagnetism; Paleoenvironment; Goethite; Magnetite; Indian ocean.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00264/37488/36828.pdf
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Magnetic fabric of Bengal fan sediments: Holocene record of sedimentary processes and turbidite activity from the Ganges-Brahmaputra river system ArchiMer
Moreno, Eva; Caroir, Fabien; Fournier, Lea; Fauquembergue, Kelly; Zaragosi, Sébastien; Joussain, Ronan; Colin, Christophe; Blanc-valleron, Marie-madeleine; Baudin, François; De Garidel-thoron, Thibault; Valet, Jean Pierre; Bassinot, Franck.
We present here a study based on the Anisotropy of Magnetic Susceptibility (AMS) and magnetic mineralogy carried out on the composite core MD17&18taken from the eastern levee of the active channel of the middle Bengal Fan in the Indian Ocean. Based on C-14 dating, the sedimentary sequence covers 9.8 ka in 39 m of sediment. It therefore records at very high resolution the variations in continental material exported to the ocean by the Ganges-Brahmaputra river system during the Holocene. This sequence was divided into two units according to turbidite activity: Unit 1 from 9.8 to 9.2 ka cal. Representing 39 m of coarse-grained turbidite sequences (coarse silts to fine sands) and extremely high sedimentation rates. Unit 2 of 9.2 ka cal. BP to the present...
Tipo: Text Palavras-chave: Bengal fan; Holocene; Turbidite activity; Magnetic fabric; Magnetic mineralogy.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00652/76388/77402.pdf
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Methanogenesis and clay minerals diagenesis during the formation of dolomite nodules from the Tortonian marls of southern Spain ArchiMer
Pierre, Catherine; Rouchy, Jean-marie; Blanc-valleron, Marie-madeleine; Etoubleau, Joel; Fouquet, Yves.
Dolomite nodules are widespread within the Tortonian marls of Fortuna and Lorca basins in southern Spain. They occur as large bodies of various forms (round, ovoid, tabular) that are parallel or secant relative to the stratification. They are massive and present sometimes internal conduits that are considered as drains used for the migration of fluids. This study brings new results on the mineralogy and elemental and isotopic geochemistry of these dolomite nodules to better describe the processes that were occurring during their formation. The diagenetic reactions that have driven authigenic dolomite precipitation within the sediments involved on the one hand methanogenesis that produced 13C-poor CH4 and 13C-rich CO2, on the other hand carbonate and...
Tipo: Text Palavras-chave: Authigenic dolomite nodules; Elemental geochemistry; Oxygen and carbon isotopes; Methanogenesis; Clay minerals diagenesis.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00266/37752/35803.pdf
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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 ArchiMer
Ruffine, Livio; Ondreas, Helene; 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, Francoise; Thomas, Bastien; Roubi, Angelique; Legoix, Ludovic Nicolas; Burnard, Pete; Chevalier, Nicolas; Lu, Hailong; Dupre, Stephanie; Fontanier, Christophe; Dissard, Delphine; Olgun, Nazli; Yang, Hailin; Strauss, Harald; Ozaksoy, Volkan; Perchoc, Jonathan; Podeur, Christian; Tarditi, Corinne; Ozbeki, Eyyup; Guyader, Vivien; Marty, Bernard; Madre, David G; Pitel-roudaut, Mathilde; Grall, Celine; Embriaco, Davide; Polonia, Mina; Gasperini, Lucas; Cagatay, M. Namik; Henry, Pierre; Geli, Louis.
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...
Tipo: Text Palavras-chave: Acoustic survey; Authigenic carbonates; Biogeochemistry; Chemical analyses; Cold seeps; Dissolved major elements; Fluid seepage; Geology; In situ Raman analysis; Methane; ROV dives.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00433/54434/55783.pdf
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