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| Needham, H.d.; Francheteau, Jean. |
| The Rift Valley between 36° 42'N and 36° 55'N in the Atlantic Ocean is 31 km wide, with half-widths of 12 and 19 km for the western and eastern sides respectively. Both outer edges of the Rift Valley stand about 1500 m above an Inner Floor where very fresh pillow lavas occur. The Inner Floor probably includes the locus of new crust ; and its bordering slopes, which are particularly well-defined on the western side, limit to less than about 2.5 km the width of the zone over which new crust may have evolved with little or no vertical displacement. The width of the locus of new crust may be less than 0.5 km between 36° 45'N and 36° 47'N, where the deepest slopes of the Rift Valley walls nearly merge. Near 36° 50'N, the Inner Floor accommodates an... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1974 |
URL: http://archimer.ifremer.fr/doc/1974/publication-5159.pdf |
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| Bellaiche, G.; Cheminee, J.l.; Francheteau, Jean; Hekinian, Roger; Le Pichon, Xavier; Needham, H.d.; Ballard, R.d.. |
| THE Rift Valley of the Mid-Atlantic Ridge, within which lies a segment of the accreting plate boundary between Africa and North America, is well defined between 36°40'N and 36°55' N. It is about 30 km wide and 1.5 km deep in that area (Fig. 1). This small portion of the rift, WSW of the Azores, was chosen as the primary target of the French-American Mid-Oceanic Undersea Survey (FAMOUS) programme, and many surface ship studies have heen conducted already. We report here preliminary results of seven dives into the deepest part of the Rift Valley that were made by the bathyscaphe Archimède during the summer of 1973. [NOT CONTROLLED OCR] |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1974 |
URL: http://archimer.ifremer.fr/doc/1974/publication-5443.pdf |
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| Francheteau, Jean; Needham, H.d.; Choukroune, P.; Juteau, T.; Seguret, M.; Ballard, R.d.; Fox, P.j.; Normark, W.; Carranza, X; Cordoba, D.; Guerrero, J.; Rangin, C.; Bougault, Henri; Cambon, Pierre; Hekinian, Roger. |
| Massive ore-grade zinc, copper and iron sulphide deposits have been found at the axis of the East Pacific Rise.Although their presence on the deep ocean-floor had been predicted there was no supporting observational evidence. The East Pacific Rise deposits represent a modern analogue of Cyprus-type sulphide ores associated with ophiolitic rocks on land.They contain at least 29% zinc metal and 6% metallic copper.Their discovery will provide a new focus for deep-sea exploration, leading to new assessments of the concentration of metals in the upper layers of the oceanic crust. [NOT CONTROLLED OCR] |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1979 |
URL: http://archimer.ifremer.fr/doc/1979/publication-5278.pdf |
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| Francheteau, Jean; Needham, H.d.; Choukroune, P.; Juteau, T.; Seguret, M.; Ballard, R.d.; Fox, J.p.; Normark, W.r.; Carranza, A.; Cordoba, D.; Guerrero, J.; Rangin, C.. |
| A submersible study has been conducted in February - March 1978 at the axis of the East Pacfic Rise near 21°N. The expedition CYAMEX, the first submersible program to be conducted on the East Pacific Rise, is part of the French-American-Mexican project RiTA (Rivera-Tamayo), a 3-year study devoted to detailed geological and geophysical investigations of the East Pacific Rise Crest. On the basis of the 15 dives made by CYANA in the axial area of the Rise, a morphological and tectonic zonation can be established for this moderately-fast spreading center. A narrow, 0.6 to 1.2 km wide zone of extrusion (zone 1), dominated by young lava flows, is flanked by a highly fissured and faulted zone of extension (zone 2) with a width of 1 to 2 km. Further out, zone... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/1980/publication-5332.pdf |
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