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| Registros recuperados: 11 | |
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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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| Sichler, Bertrand; Hekinian, Roger. |
| The St. Paul Fracture Zone (FZ) in the equatorial Atlantic is interrupted by three intratransform ridge (ITR) spreading centers. A detailed magnetic survey, corrected for the diurnal variations using a moored magnetic station, six submersible dives, and three bottom-towed video camera tracks provide data on the most eastern ITR (0degrees37'N, 25degrees27'W). Visual observations and submersible sampling displayed a high ultramafic/volcanic ratio, supporting the assumption that the ITR is in a magmatically starved state. Volcanics were mainly found on the rift valley floor from 4700 to 4000 m and as a thin cap (<160 m) on the top of the eastern rift crest (2700 m). Most of the rift walls consist essentially of serpentinized peridotites and gabbros. The... |
| Tipo: Text |
Palavras-chave: Magnetic anomaly; Equatorial Atlantic; Stochastic inversion. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/00000/10223/9585.pdf |
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| Le Pichon, Xavier; Cressard, Alain; Mascle, Jean; Pautot, Guy; Sichler, Bertrand. |
| In 1921 the "Pourquoi pas?" undertook, under the authority of J. Charcot, an identification of the Rockall bank (2). The petrographic nature of this relief was studied by Lacroix (2) who concluded to aegirine granite dated, since then, by Miller (3) and Sabine (4), from the early Tertiary period. At the beginning of the Noratlante cruise, in August 1969, the "J. Charcot" carried out a number of profiles, tallying the Porcupine and the Rockall area (fig.1). In addition to the gravimetry and magnetism recordings, an oblique-reflection profile and six Flexotir seismic-reflection profiles (with a frequency comprised of between 10 and 30 cycles) were carried out. We only present here the first results based on this last technique. |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1970 |
URL: http://archimer.ifremer.fr/doc/1970/publication-4873.pdf |
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| Bougault, Henri; Appriou, P; Birolleau, A; Charlou, Jean-luc; Crane, K; Etoubleau, Joel; Fouquet, Yves; Gente, P; Harmegnies, Francois; Landure, Jean-yves; Le Noac'H, A; Pelle, Henri; Sichler, Bertrand; Voisset, Michel; Watremez, Pierre; Vaslet, N; Jean Baptiste, P. |
| Tipo: Text |
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| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00070/18104/15652.pdf |
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| Galibert, Pierre-yves; Sichler, Bertrand; Smith, Brigitte; Bonhommet, Norbert. |
| A paleomagnetic investigation has been undertaken to study the Asal rift zone and the border zone between Asal and Yoboki. In both zones sampling has been carried out along the vertical surfaces of the sections exposed by the rift faults and the Edayle canyon, on the south side of Ghoubbet. The results of the rift zone indicate a magnetization of normal polarity for all the sites. Moreover, the corrections for the tilt of the strata show that in the "small rift" the observable tectonism is older than the emplacement of the lava flows. Outside the rift, 18 flows with normal and reversed polarity belong to the stratoid series (1-4 m.y.). They yield a mean direction of D = 10°E and 1 = + 13°, which can be explained either by a non dipolar or non CO-axial... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/1980/publication-5310.pdf |
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| Olivet, Jean-louis; Sichler, Bertrand; Thonon, Pierre; Le Pichon, Xavier; Martinais, Guy; Pautot, Guy. |
| The Gibbs fracture moves the central Rift of the Mid-Atlantic Ridge 370 km to the left at latitude 53O north. It is the only fracture located between Europe and America that can be compared to the large equatorial fractures mapped by B.C. Heezen and M. Tharp between Africa and America. Its morphology is a major element in the understanding of the structural framework of the northern Atlantic Ocean. The identification of its extension to the west was one of the proposed focuses for the first Noratlante expedition of the R.V. Jean-Charcot (conducted in August 1969 under the authority of the C.N.E.X.O.). J.T. Wilson (2) suggested, in his hypothesis of sea-bed spreading from the dorsal axis, that such fractures are "transforming faults" that are active only... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1970 |
URL: http://archimer.ifremer.fr/doc/1970/publication-4875.pdf |
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| Lafoy, Y.; Géli, Louis; Klingelhoefer, Frauke; Vially, R.; Sichler, Bertrand; Nouzé, Herve. |
| A deep seismic survey conducted within the western part of New Caledonia's Exclusive Economic Zone (EEZ) (Figure 1) from 8 September–5 October 2004 revealed for the first time the thinned continental and oceanic natures of the crust beneath the eastern Tasman Sea. The survey which was conducted by an international group of scientists a board the Institut Francais de Recherche pour l'Exploitation de la MER (Ifremer) R/V L'Atalante, aimed at improving the understanding of the geological framework, crustal characteristics, and evolution of the submarine basin and ridge system located west of New Caledonia's mainland. The study area, located east of both Australia and the oceanic Tasman Sea Basin, is composed of continental fragments: the Lord Howe Rise and... |
| Tipo: Text |
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| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/00210/32141/30598.pdf |
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| Auffret, Gerard; Sichler, Bertrand; Coleno, B. |
| Critical speeds for erosion, transport and deposition of sedimentary particles and prevailing bottom currents intensities are in such a range that the textural properties of the sediment silt fraction may be correlated to the intensity of the deep circulation. On the other hand, the long axis of the sediment magnetic susceptibility ellipsoid, should be aligned according to the current flow. These hypotheses have been positively tested in five abyssal areas. The authors then apply textural studies to the study of Cenozoic deep water circulation in two continental margin areas (Bay of Biscay and Western mediterranean, DSDP Site 400 and Site 372). The results are in good agreement with informations provided by micropaleontological and geochemical... |
| Tipo: Text |
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| Ano: 1981 |
URL: http://archimer.ifremer.fr/doc/1981/publication-5358.pdf |
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| Sichler, Bertrand. |
| Geological and geophysical data now availabe in Afar and neighbouring areas suggest that plate tectonics is usable in this areas if one accepts, for some parts of the puzzle the notion of hinge points. In this context, the Danakil bloc con be considered as a moving piece hinged in the North to the Nubian plate which is assumed to be fixed, and hinged in the south to the Red Sea rift without the need for a transform Fault and to explain some morphological features of the Afar. The life of such a crank-arm is short and it exhibits zones of crustal weakness and in the future the crank-arm itself, or more probably the northern hinge point must rupture. Such a hypothesis can explain the occurence in the oceans of oblique abnormal structures like Rockall bank in... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/1980/publication-5318.pdf |
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| Registros recuperados: 11 | |
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