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| Registros recuperados: 12 | |
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| Pelleter, Ewan; Fouquet, Yves; Etoubleau, Joel; Cheron, Sandrine; Labanieh, Shasa; Josso, Pierre; Bollinger, Claire; Langlade, Jessica. |
| The Wallis and Futuna back-arc system is a complex area composed of at least two active oceanic spreading centers (Futuna and Alofi spreading centers) and young volcanic zones characterized by diffuse magmatism locally affected by the Samoan hotspot. This geological setting is favorable to the establishment of hydrothermal systems either high-temperature (HT) hydrothermal venting or low-temperature (LT) diffuse flow. During the 2010 Futuna cruise aboard R/V L'Atalante, three remarkable inactive LT Fe-Si-Mn deposits have been discovered (i.e. Utu Uli, Anakele and Utu Sega). Some of the Mn-rich precipitates exhibit the highest base metals concentrations so far recorded in ferromanganese rocks including the well-documented hydrogenetic crusts and polymetallic... |
| Tipo: Text |
Palavras-chave: Hydrothermal; Diffuse flow; Manganese oxyhydroxides; Metal-rich; Seafloor; Wallis and Futuna Island; South-West Pacific. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00350/46164/45862.pdf |
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| Lamarche, Geoffroy; Lurton, Xavier. |
| Multibeam echosounders are becoming widespread for the purposes of seafloor bathymetry mapping, but the acquisition and the use of seafloor backscatter measurements, acquired simultaneously with the bathymetric data, are still insufficiently understood, controlled and standardized. This presents an obstacle to well-accepted, standardized analysis and application by end users. The Marine Geological and Biological Habitat Mapping group (Geohab.org) has long recognized the need for better coherence and common agreement on acquisition, processing and interpretation of seafloor backscatter data, and established the Backscatter Working Group (BSWG) in May 2013. This paper presents an overview of this initiative, the mandate, structure and program of the working... |
| Tipo: Text |
Palavras-chave: Multibeam echosounders; Calibration; Reflectivity; Mapping; Seafloor. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00385/49655/50179.pdf |
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| Gay, Aurelien; Lopez, M; Cochonat, Pierre; Sermondadaz, G. |
| A new polygonal fault system has been identified in the Lower Congo Basin. This highly faulted interval (HFI), 700+/-50 m thick, is characterized by small extensional faults displaying a polygonal pattern in plan view. This kind of fracturing is attributed to volumetric contraction of sediments during early stages of compaction at shallow burial depth. 3-D seismic data permitted the visualization of the progressive deformation of furrows during burial, leading to real fractures, visible on seismic sections at about 78 m below seafloor. We propose a new geometrical model for volumetrical contraction of mud-dominated sediments. Compaction starts at the water-sediment interface by horizontal contraction, creating furrows perpendicular to the present day... |
| Tipo: Text |
Palavras-chave: Water sediment interface; Seafloor; Sedimentary basin; Geometrical model; Furrow; Fault system. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-1115.pdf |
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| Ondreas, Helene; Aslanian, Daniel; Geli, Louis; Olivet, Jean-louis; Briais, Anne. |
| The spreading rate at the Pacific-Antarctic Ridge (PAR) increases rapidly from 54 mm/yr near Pitman Fracture Zone (FZ) up to 76 mm/yr near Udintsev FZ, resulting in three domains of axial morphology: an axial valley south of Pitman FZ, an axial high north of Saint Exupery FZ, and in between, the transitional domain extends over 650 km. It comprises sections of ridge with an axial valley or an axial high and generally displays a very low cross-sectional relief. It is also characterized by two propagating rifts. Two domains of different seafloor roughness appear south of Udintsev FZ: east of 157 degreesW these two domains are separated by a 1000-km V-shaped boundary. West of 157 degreesW, the boundary approximately coincides with Chron 3a or Chron 4. The... |
| Tipo: Text |
Palavras-chave: Spreading; Segmentation; Geomorphology; Seafloor; Ridge. |
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/2001/publication-438.pdf |
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| Dekov, V. M.; Lalonde, Stefan; Kamenov, G. D.; Bayon, Germain; Shanks, W. C., Iii; Fortin, D.; Fouquet, Yves; Moscati, R. J.. |
| An inactive vent field comprised of dead chimneys was discovered on the ultrafast East Pacific Rise (EPR) at 18°S during the research campaign NAUDUR with the R/V Le Nadir in December 1993. One of these chimneys was sampled, studied and found to be largely composed of silica-mineralized bacterial-like filaments. The filaments are inferred to be the result of microbial activity leading to silica (± Fe-oxyhydroxide) precipitation. The chimney grew from the most external layer (precipitated 226 ± 4 yr. B.P.) towards the central chimney conduit. Hydrothermal activity ceased 154 ± 13 yr. B.P. and the chimney conduit was completely sealed. Mixing between an end-member hydrothermal fluid and seawater explains the Sr–Nd isotopic composition of the chimney.... |
| Tipo: Text |
Palavras-chave: Chimney; C-O-Si-Sr-Nd-Pb-Th-U isotopes; Hydrothermal; Seafloor; Silica. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00280/39143/37698.pdf |
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| Sulpis, Olivier; Boudreau, Bernard P.; Mucci, Alfonso; Jenkins, Chris; Trossman, David S.; Arbic, Brian K.; Key, Robert M.. |
| Oceanic uptake of anthropogenic CO2 leads to decreased pH, carbonate ion concentration, and saturation state with respect to CaCO3 minerals, causing increased dissolution of these minerals at the deep seafloor. This additional dissolution will figure prominently in the neutralization of man-made CO2 . However, there has been no concerted assessment of the current extent of anthropogenic CaCO3 dissolution at the deep seafloor. Here, recent databases of bottom-water chemistry, benthic currents, and CaCO3 content of deep-sea sediments are combined with a rate model to derive the global distribution of benthic calcite dissolution rates and obtain primary confirmation of an anthropogenic component. By comparing preindustrial with present-day rates, we determine... |
| Tipo: Text |
Palavras-chave: Ocean acidification; Seafloor; CaCO3; Dissolution; Anthropogenic CO2. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00675/78677/80887.pdf |
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| Gerigny, Olivia; Brun, Melanie; Fabri, Marie-claire; Tomasino, Corinne; Le Moigne, Morgan; Jadaud, Angelique; Galgani, Francois. |
| Seafloor litter has been studied both on the continental shelves (by trawling during 24 years) and in canyons (by ROV) of the French Mediterranean sea Water (FMW). On the continental shelf, mean densities range from 49.63 to 289.01 items/km2. The most abundant categories were plastic, glass/ceramics, metals and textiles. Trend analysis shows a significant increase in plastic quantities during the study period. Plastics accumulate at all depths, with heavier items being found in deeper areas, while the continental slope-break appears as a clean area. The spatial distribution of litter revealed the influence of geomorphologic factors, anthropic activities, shipping route, river inputs. All the canyons are affected by debris but coastal canyons (Ligurian Sea... |
| Tipo: Text |
Palavras-chave: Marine litter; Seafloor; Canyon; Mediterranean Sea; Gulf of Lion; Corsica. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00507/61868/66074.pdf |
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| Canals, Miquel; Pham, Christopher K.; Bergmann, Melanie; Gutow, Lars; Hanke, Georg; Van Sebille, Erik; Angiolillo, Michela; Buhl-mortensen, Lene; Cau, Alessando; Ioakeimidis, Christos; Kammann, Ulrike; Lundsten, Lonny; Papatheodorou, George; Purser, Autun; Sanchez-vidal, Anna; Schulz, Marcus; Vinci, Matteo; Chiba, Sanae; Galgani, Francois; Langenkämper, Daniel; Möller, Tiia; Nattkemper, Tim W.; Ruiz, Marta; Suikkanen, Sanna; Woodall, Lucy; Fakiris, Elias; Molina Jack, Maria Eugenia; Giorgetti, Alessandra. |
| The seafloor covers some 70% of the Earth's surface and has been recognized as a major sink for marine litter. Still, litter on the seafloor is the least investigated fraction of marine litter, which is not surprising as most of it lies in the deep sea, i.e. the least explored ecosystem. Although marine litter is considered a major threat for the oceans, monitoring frameworks are still being set up. This paper reviews current knowledge and methods, identifies existing needs, and points to future developments that are required to address the estimation of seafloor macrolitter. It provides background knowledge and conveys the views and thoughts of scientific experts on seafloor marine litter offering a review of monitoring and ocean modeling techniques.... |
| Tipo: Text |
Palavras-chave: Seafloor; Marine litter; Trawl surveys; Visual surveys; Deep sea; Modelling; Data harmonisation. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00657/76947/78156.pdf |
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| Dekov, Vesselin M.; Rouxel, Olivier; Kouzmanov, Kalin; Bindi, Luca; Asael, Dan; Fouquet, Yves; Etoubleau, Joel; Burgaud, Gaetan; Walle, Markus. |
| Active and inactive hydrothermal chimneys composed almost entirely of enargite and luzonite, rare minerals in seafloor hydrothermal deposits, were found at the summits of two submarine volcanoes, North Su and Kaia Natai, in the Manus Back-Arc Basin. Detailed mineralogical and geochemical studies revealed that most probably these deposits precipitated at T = 200°–330 °C and high fS2. The negative δ34S values (− 8.58 to − 3.70‰) of the enargite-luzonite are best explained by disproportionation reactions of magmatic SO2 and suggest that the high fS2 is likely provided by direct magmatic input of SO2 into the hydrothermal system. Fractionation of Cu stable isotopes during the precipitation of enargite-luzonite (δ65Cu ranges from − 0.20 to + 0.35‰) is inferred... |
| Tipo: Text |
Palavras-chave: Enargite; Epithermal; Hydrothermal vent; Luzonite; S-Cu isotopes; Seafloor. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00337/44844/44432.pdf |
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| Galgani, Francois; Hanke, Georg; Maes, Thomas. |
| Marine debris is commonly observed everywhere in the oceans. Litter enters the seas from both land-based sources, from ships and other installations at sea, from point and diffuse sources, and can travel long distances before being stranded. Plastics typically constitute the most important part of marine litter sometimes accounting for up to 100 % of floating litter. On beaches, most studies have demonstrated densities in the 1 item m−2 range except for very high concentrations because of local conditions, after typhoons or flooding events. Floating marine debris ranges from 0 to beyond 600 items km−2. On the sea bed, the abundance of plastic debris is very dependent on location, with densities ranging from 0 to >7700 items km−2, mainly in coastal... |
| Tipo: Text |
Palavras-chave: Marine litter; Plastic; Distribution; Beaches; Seafloor; Microplastics; Floating litter. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00667/77914/80097.pdf |
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| Registros recuperados: 12 | |
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