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| Registros recuperados: 10 | |
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| Szitkar, Florent; Dyment, Jerome; Fouquet, Yves; Choi, Yujin; Honsho, Chie. |
| The analysis of high-resolution vector magnetic data acquired by deep-sea submersibles (DSSs) requires the development of specific approaches adapted to their uneven tracks. We present a method that takes advantage of (1) the varying altitude of the DSS above the seafloor and (2) high-resolution multibeam bathymetric data acquired separately, at higher altitude, by an Autonomous Underwater Vehicle, to estimate the absolute magnetization intensity and the magnetic polarity of the shallow subseafloor along the DSS path. We apply this method to data collected by DSS Nautile on a small active basalt-hosted hydrothermal site. The site is associated with a lack of magnetization, in agreement with previous findings at the same kind of sites: the contrast between... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00252/36300/34829.pdf |
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| Choe, Hanjin; Dyment, Jerome. |
| Seafloor spreading magnetic anomalies formed at mid‐ocean ridges initially display strong amplitudes that decay within the first 10 million years as a result of pervasive hydrothermal circulation and alteration. The amplitudes do not vary much for older oceanic crust, suggesting that the thickening sediments hinder heat advection. Here we show, however, that a systematic loss of ~20 % in the amplitude of the anomalies arises between the outer rise and the trench on old ocean crust approaching the Japan and Kuril subduction zones. We interpret this decay as reflecting the opening of normal faults and fissures caused by extension on the outer flexural rise, and the subsequent renewed circulation of seawater into the oceanic crust, resulting in additional... |
| Tipo: Text |
Palavras-chave: Hydrothermal circulation; Marine magnetic anomaly; Subduction zone; Outer rise; Bending oceanic crust. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00614/72611/71621.pdf |
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| Hananto, Nugroho; Boudarine, Asmoune; Carton, Helene; Singh, Satish C.; Avianto, Praditya; Dyment, Jerome; Qin, Yanfang; Ghosal, Dibakar; Zuraida, Rina; Tapponnier, Paul E.; Deplus, Christine; Sieh, Kerry. |
| The Wharton Basin in the Indian Ocean is one of the most extensively deforming ocean basins, as confirmed by the occurrence of several very large earthquakes starting from January 12, 2012 with Mw 7.2 followed by the great earthquakes of April 11, 2012 with Mw 8.6 and Mw 8.2. Although the Mw 7.2 and Mw 8.2 earthquakes seem to have ruptured the re-activated N–S striking fracture zones, the largest event (Mw 8.6) required the rupturing of several faults, oblique to each other, in a very complex manner. In order to understand the nature of deformation in these earthquakes rupture zones, we recently acquired 90 000 km2 of bathymetry, 11 400 km of sub-bottom profiling, gravity and magnetic data covering the rupture areas of the 2012 earthquakes east of the... |
| Tipo: Text |
Palavras-chave: The 2012 Indian Ocean earthquake; Diffuse deformation; Wharton Basin; Plate bending; Shear zones; Normal faults. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00456/56738/58526.pdf |
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| Lartaud, Franck; De Rafelis, Marc; Oliver, Graham; Krylova, Elena; Dyment, Jerome; Ildefonse, Benoit; Thibaud, Remy; Gente, Pascal; Hoise, Eva; Meistertzheim, Anne-leila; Fouquet, Yves; Gaill, Francoise; Le Bris, Nadine. |
| Hydrothermal circulation at ultramafic-hosted sites supports a large variety of high-and low-temperature hydrothermal vents and associated ecosystems. The discovery of abundant fossil vesicomyid and thyasirid shell accumulations at the ridge crest, approximately 2.5 km east of the active Rainbow vent field on the Mid-Atlantic Ridge (MAR, 36 degrees 13'N), increased our knowledge regarding the diversity of vent communities at slow spreading ridges. Bivalve molluscs of the family Vesicomyidae were represented by the genus Phreagena. Here we present the first record of this genus in the Atlantic Ocean. This second vesicomyid species known from the MAR, Phreagena sp., was found to be associated with a Thyasira species that is affiliated with T. southwardae (at... |
| Tipo: Text |
Palavras-chave: Ultramafic-hosted; Mid-Atlantic Ridge; Bivalve shells; Vesicomyidae; Thyasiridae; Carbon and oxygen isotopes. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00012/12301/9093.pdf |
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| Lartaud, Franck; Little, Crispin T. S.; De Rafelis, Marc; Bayon, Germain; Dyment, Jerome; Ildefonse, Benoit; Gressier, Vincent; Fouquet, Yves; Gaill, Francoise; Le Bris, Nadine. |
| Among the deep-sea hydrothermal vent sites discovered in the past 30 years, Lost City on the Mid-Atlantic Ridge (MAR) is remarkable both for its alkaline fluids derived from mantle rock serpentinization and the spectacular seafloor carbonate chimneys precipitated from these fluids. Despite high concentrations of reduced chemicals in the fluids, this unique example of a serpentinite-hosted hydrothermal system currently lacks chemosynthetic assemblages dominated by large animals typical of high-temperature vent sites. Here we report abundant specimens of chemosymbiotic mussels, associated with gastropods and chemosymbiotic clams, in approximately 100 kyr old Lost City-like carbonates from the MAR close to the Rainbow site (36 degrees N). Our finding shows... |
| Tipo: Text |
Palavras-chave: Bathymodiolus; Ghost City; Ultramafic-hosted; Mid-ocean ridge; Ecogeochemistry. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00036/14748/15832.pdf |
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| Granot, Roi; Dyment, Jerome. |
| The kinematic evolution of the West Antarctic rift system has important consequences for regional and global geodynamics. However, due to the lack of Neogene seafloor spreading at the plate boundary and despite being poorly resolved, East-West Antarctic motion was assumed to have ended abruptly at 26 million years ago. Here we present marine magnetic data collected near the northern edge of the rift system showing that motion between East and West Antarctica lasted until the middle Neogene (similar to 11 million years ago), long after the cessation of the known mid-Cenozoic pulse of motion. We calculate new rotation parameters for the early Neogene that provide the kinematic framework to understand the varied lithospheric settings of the Transantarctic... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00689/80081/83110.pdf |
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| Bandy, W; Michaud, F; Dyment, Jerome; Mortera Gutierrez, C; Bourgois, J; Calmus, T; Sosson, M; Ortega Ramirez, J; Royer, J; Pontoise, B; Sichler, Bertrand. |
| To better understand the recent motion of the Pacific plate relative to the Rivera plate and to better define the limitations of the existing Rivera-Pacific plate motion models for accurately predicting this motion, total-field magnetic data, multibeam bathymetric data and sidescan sonar images were collected during the BART and FAMEX campaigns of the N/O L'Atalante conducted in April and May 2002 in the area surrounding the Moctezuma Spreading Segment of the East Pacific Rise, located offshore of Manzanillo, Mexico, at 106 degrees 16'W, between 17.8 degrees N and 18.5 degrees N. Among the main results are: (1) the principle transform displacement zone of the Rivera Transform is narrow and well defined east of 107 degrees 15'W and these azimuths should be... |
| Tipo: Text |
Palavras-chave: Plate motions; Plate boundary morphology; Mexico; Rivera plate; Rivera Transform; East Pacific Rise. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4486.pdf |
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| Andreani, Muriel; Escartin, Javier; Delacour, Adelie; Ildefonse, Benoit; Godard, Marguerite; Dyment, Jerome; Fallick, Anthony E.; Fouquet, Yves. |
| Rainbow is a dome-shaped massif at the 36°14′N nontransform offset along the Mid-Atlantic Ridge. It hosts three ultramafic-hosted hydrothermal sites: Rainbow is active and high temperature; Clamstone and Ghost City are fossil and low temperature. The MoMARDREAM cruises (2007, 2008) presented here provided extensive rock sampling throughout the massif that constrains the geological setting of hydrothermal activity. The lithology is heterogeneous with abundant serpentinites surrounding gabbros, troctolites, chromitites, plagiogranites, and basalts. We propose that a W dipping detachment fault, now inactive, uplifted the massif and exhumed these deep-seated rocks. Present-day deformation is accommodated by SSW-NNE faults and fissures, consistent with oblique... |
| Tipo: Text |
Palavras-chave: Rainbow; Hydrothermal; Serpentinization; Atlantic ridge. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00210/32151/30609.pdf |
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| Louvel, Veronique; Dyment, Jerome; Sibuet, Jean-claude. |
| The deep seismic reflection profile Western Approaches Margin (WAM) cuts across the Goban Spur continental margin, located southwest of Ireland. This non-volcanic margin is characterized by a few tilted blocks parallel to the margin. A volcanic sill has been emplaced on the westernmost tilted block. The shape of the eastern part of this sill is known from seismic data, but neither seismic nor gravity data allow a precise determination of the extent and shape of the volcanic body at depth. Forward modelling and inversion of magnetic data constrain the shape of this volcanic sill and the location of the ocean-continent transition. The volcanic body thickens towards the ocean, and seems to be in direct contact with the oceanic crust. In the contact zone, the... |
| Tipo: Text |
Palavras-chave: Continental margin; Goban Spur; Magnetic anomalies; Ocean-continent boundary. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00337/44777/44601.pdf |
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| Szitkar, Florent; Dyment, Jerome; Choi, Yujin; Fouquet, Yves. |
| High-resolution magnetic surveys acquired near the seafloor show that active basalt-hosted hydrothermal sites are associated with zones of lower magnetization. This observation may reflect the thermal demagnetization of a hot hydrothermal zone, the alteration of basalt affected by hydrothermal circulation, and/or the presence of thick, nonmagnetic hydrothermal deposits. In order to discriminate among these inferences, we acquired vector magnetic data 50 m above inactive hydrothermal site Krasnov using the Remotely Operated Vehicle (ROV) Victor. This deep hydrothermal site, located 7 km east of the Mid-Atlantic Ridge (MAR) axis at 16°38′N, is dissected by major normal faults and shows no evidence of recent hydrothermal activity. It is therefore a perfect... |
| Tipo: Text |
Palavras-chave: Magnetic anomalies; Hydrothermalism; Alteration; Modeling. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00188/29915/28375.pdf |
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| Registros recuperados: 10 | |
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