HR: 1340h
AN: T53B-1306    [Abstracts]
TI: Further Geological Sampling Around the Rainbow Hydrothermal Site, Mid-Atlantic Ridge
AU: * Ildefonse, B
EM: benoit.ildefonse@um2.fr
AF: Géosciences Montpellier, CNRS, Université Montpellier 2, CC60, montpellier cedex 05, 34095, France
AU: Andréani, M
EM: muriel.andreani@gm.univ-montp2.fr
AF: Géosciences Montpellier, CNRS, Université Montpellier 2, CC60, montpellier cedex 05, 34095, France
AU: Hoisé, E
EM: hoise@geologie.ens.fr
AF: ENS, Laboratoire de géologie, 24 rue Lhomond, Paris, 75005, France
AU: Ballu, V
EM: ballu@ipgp.jussieu.fr
AF: Gravimétrie et Géodynamique, IPGP, CNRS, 4 place Jussieu, Paris cedex 05, 75252, France
AU: Escartin, J
EM: escartin@ipgp.jussieu.fr
AF: Géosciences Marines, IPGP, CNRS, 4 place Jussieu, Paris cedex 05, 75252, France
AU: Dyment, J
EM: jdy@ipgp.jussieu.fr
AF: Géosciences Marines, IPGP, CNRS, 4 place Jussieu, Paris cedex 05, 75252, France
AU: Gaill, F
EM: Francoise.Gaill@snv.jussieu.fr
AF: Systématique Adaptation Evolution, CNRS, Université Pierre et Marie Curie, 7 Quai Saint Bernard, Paris, 75005, France
AU: Fouquet, Y
EM: Yves.Fouquet@ifremer.fr
AF: Ifremer, DRO-GM, BP70, Plouzané, 29270, France
AB: The Rainbow hydrothermal site, at 36°14'N on the Mid-Atlantic Ridge, is one of the few known site hosted in ultramafic basement. The MOMAR DREAM cruise (July 2007, R/V Pourquoi Pas ?) combined biological and geological objectives to study the role of abundant iron in controlling geological, biological and hydrological active processes at all scales. Two Nautile dives and a dredging program were achieved to further constrain the lithology and geological structures on the seafloor at the scale of the massif that hosts Rainbow. This massif is an inside corner high of the non-transform offset between the AMAR and South AMAR second-order ridge segments, and presents the characteristic dome morphology of oceanic core complexes. The abundant sediment cover of the massif precludes continuous geological mapping and completely successful dredging. However, our limited sampling is consistent with the lithological variability encountered in other oceanic core complexes along the Mid-Atlantic Ridge. The Rainbow serpentinite basement was continuously observed to a distance of about 1 km to the south of the hydrothermal site, with serpentinites sampled along N-S trending, fault planes steeply dipping to the West. Serpentinites were also found on the northwestern, northern, and northeastern flanks of the massif. Approximately 800 m the North of the hydrothermal site, the most prominent outcrop, cut by a family of subvertical, ~ E-W faults, is at least partly made of olivine- orthopyroxene bearing gabbro. Basalts and fresh basaltic glass were also recovered in talus and sediments on the Southwest and Northeast flanks of the massif.
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 3035 Midocean ridge processes
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 8416 Mid-oceanic ridge processes (1032, 3614)
DE: 8424 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting