Consulta: subjectFacets:"Authigenic carbonates"
Registros recuperados: 8
Data/hora: 09/06/2024 04:17:23

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

Microbial utilization of rare earth elements at cold seeps related to aerobic methane oxidation
Provedor de dados: 5
Autores: Bayon, Germain; Lemaitre, Nolwenn; Barrat, Jean-alix; Wang, Xudong; Feng, Dong; Duperron, Sebastien.
A major breakthrough in the field of rare earth element (REE) geochemistry has been the recent discovery of their utility to microbial life, as essential metalloenzymes catalyzing the oxidation of methanol to formaldehyde. Lanthanide-dependent bacteria are thought to be ubiquitous in marine and terrestrial environments, but direct field evidence of preferential microbial utilization of REE in natural systems is still lacking. In this study, we report on the REE and trace element composition of the tube of a siboglinid worm collected at a methane seep in the Gulf of Guinea; a tube-dwelling annelid that thrives in deep-sea chemosynthetic ecosystems. High-resolution trace element profiles along the chitin tube indicate marked enrichments of lanthanum (La) and...
Tipo: Text
Palavras-chave: Tubeworms; Siboglinidae; Lanthanide-dependent bacteria; Metalloenzymes; Methylotrophy; Regab; Authigenic carbonates; Archaean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00643/75496/76352.pdf

U-Th stratigraphy of a cold seep carbonate crust
Provedor de dados: 5
Autores: Bayon, Germain; Henderson, G. M.; Bohn, Marcel.
On continental margins, oxidation of methane-rich fluids from the sediment often leads to formation of authigenic carbonate pavements on the seafloor. The biogeochemical processes involved during this carbonate precipitation are increasingly understood, but little is known about the duration or mode of carbonate crust formation. Here, we report uranium and thorium concentrations and isotope compositions for a set of 14 samples drilled across an authigenic carbonate pavement, which provide the first stratigraphy for a cold-seep carbonate crust. The 5.5-cm thick crust (NL7-CC2) was collected by Submersible on the Nile deep-sea fan in an area of active fluid venting. U-Th analyses must be corrected for initial Th and measurement of co-existing sediments...
Tipo: Text
Palavras-chave: Nile fan; Cold seeps; Authigenic carbonates; U series.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6450.pdf

Seafloor authigenic carbonate crusts along the submerged part of the North Anatolian Fault in the Sea of Marmara: Mineralogy, geochemistry, textures and genesis
Provedor de dados: 5
Autores: Cagatay, M. Namik; Yildiz, Guliz; Bayon, Germain; Ruffine, Livio; Henry, Pierre.
Extensive seafloor authigenic carbonate crusts occur as pavements, mounds and chimneys along the North Anatolian Fault System (NAFS) in the Sea of Marmara. They are often covered or surrounded by patches of black Fe-sulphide-rich sediments, and associated with hydrocarbon-rich gas and brackish-water emissions in the 1250 m-deep deep basins and with deep saline formation waters and hydrocarbons emissions from mud volcanoes and anticlines on the 350 to 650 m-deep compressional highs. The authigenic carbonate crusts are commonly porous with sinter-like, botryoidal and sugary- granular textures, and constructed from cementation of framework elements consisting mainly of bivalve shells and shell fragments, serpulid tubes, fibrous microbial organic matter and...
Tipo: Text
Palavras-chave: Authigenic carbonates; Mineral and isotopic compositions; Textures and structures; U-Th ages; North Anatolian Fault; Sea of Marmara.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00399/51047/51819.pdf

U-Th isotope constraints on gas hydrate and pockmark dynamics at the Niger delta margin
Provedor de dados: 5
Autores: 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

Sr/Ca and Mg/Ca ratios in Niger Delta sediments: Implications for authigenic carbonate genesis in cold seep environments
Provedor de dados: 5
Autores: 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

Paleo-environmental controls on cold seep carbonate authigenesis in the Sea of Marmara
Provedor de dados: 5
Autores: Cremiere, Antoine; Bayon, Germain; Ponzevera, Emmanuel; Pierre, Catherine.
The factors controlling fluid emission dynamics at ocean margins are poorly understood. In particular, there are significant uncertainties on how fluid seepage at cold seeps may have responded to abrupt environmental changes in the geological past. This study reports on a detailed geochemical investigation of seafloor carbonate crusts sampled at cold seeps along the submerged part of the North Anatolian Fault system in the Sea of Marmara - an inland sea, which has experienced major paleo-environmental changes over the last deglaciation period. We also analyzed a series of authigenic carbonate concretions recovered from two sediment cores at the Western-High ridge, an active fluid venting area. The ages of seafloor carbonate crusts derived from isochron...
Tipo: Text
Palavras-chave: U-Th dating; Authigenic carbonates; Sea of Marmara; Cold seeps; Sapropel event; Carbon and oxygen isotopes.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00161/27249/25488.pdf

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
Provedor de dados: 5
Autores: 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