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| Juteau, T; Eissen, Jp; Francheteau, J; Needham, David; Choukroune, P; Rangin, C; Seguret, M; Ballard, Rd; Fox, Pj; Normark, Wr; Carranza, A; Cordoba, D; Guerrero, J. |
| Fort y basaltic rocks collected by submersible during the "Cyamex" expedition (1978) on the East PacifIc Rise at 21 oN, a moderately fast spreading segment (6 cm/year opening rate) of the mid-ocean ridge, consist of angular pillow fragments and glass buds, sheet-flow slabs and samples of columnar pillars standing in collapsed fossillava pools. Most of the rocks are from the crestal are a of the Rise. The collection shows a striking petrographic homogeneity wh en compared with the range of basalts found on other segments of midocean ridges: olivine-phyric, or highly plagioclase-phyric rocks, so common in the slowspreading "Famous" are a in the Atlantic, are absent. All samples are typical lowpotassium oceanic tholeiites with a limited fractionation trend.... |
| Tipo: Text |
Palavras-chave: Dorsale Est-PacifIque Pétrologie des basaltes sous-marins Coussins; Laves fluides; Piliers Générations de cristaux Globules de sulfure East Paciflc Rise Petrology of submarine basalts Pillows; Sheet flows; Pillars Generations of crystals Sulphide globules. |
| Ano: 1980 |
URL: http://archimer.ifremer.fr/doc/00323/43430/43112.pdf |
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| Hoffert, M; Perseil, A; Hekinian, Roger; Choukroune, P; Needham, Hd; Francheteau, J; Le Pichon, X. |
| Deep-sea hydrothermal deposits were observed, mapped and sampled in situ with the submersible "Cyana" in the Famous area of the Mid-Atlantic Ridge.Two neighbouring fields, each covering an area of about 600 m2, are associated with low, E-W trending sediment-covered ridges that lie at a depth of about 2 700 m close to the axis of Transform Fault "A".In each field the deposits are thicker (up to about 1 m) close to the small, fissure-like vents through which they were evidently delivered. Despite their heterogeneous composition, their mineralogical and chemical variations have an orderly pattern.The principal constituents are a green clay-rich material, and Fe-Mn oxides in the form of black concretions. The relative abundances of these products vary with... |
| Tipo: Text |
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| Ano: 1978 |
URL: http://archimer.ifremer.fr/doc/1978/publication-5216.pdf |
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