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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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| Francheteau, Jean; Choukroune, P.; Hekinian, Roger; Le Pichon, Xavier; Needman, H.d.. |
| Data from rock-dredging have often been used to infer that oceanic fracture zones provide a 'window' into layers of the oceanic crust lying at a depth below the surface that is approximately equivalent to the vertical offset of the fracture zone, and thus permit the reconstruction of a crustal stratigraphy for the whole of acoustic layer 2 (commonly considered to have an average thickness of ~2 km) and in some interpretations for the upper part of layer 3. Alternatively, it has been suggested that fracture zones are preferential sites of serpentinite mega-dykes differing in composition from layer 3 but containing inclusions of the third layer. The published data indicate that basalts and basaltic rubble are abundant in fracture zones and on analysis do not... |
| Tipo: Text |
Palavras-chave: Histoire Ifremer. |
| Ano: 1976 |
URL: http://archimer.ifremer.fr/doc/1976/publication-5109.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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