HR: 0800h
AN: T41E-1349 INVITED     [Abstracts]
TI: Seafloor generation at a melt-poor ultra-slow-spreading ridge
AU: * Cannat, M
EM: cannat@ipgp.jussieu.fr
AF: CNRS-Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75252 France
AU: Sauter, D
EM: daniel.sauter@eost.u-strasbg.fr
AF: CNRS-Institut de Physique du Globe de Strasbourg, 5 rue Descartes, Strasbourg, 67084 France
AU: Escartin, J
EM: escartin@ipgp.jussieu.fr
AF: CNRS-Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75252 France
AU: Mendel, V
EM: veronique.mendel@eost.u-strasbg.fr
AF: CNRS-Institut de Physique du Globe de Strasbourg, 5 rue Descartes, Strasbourg, 67084 France
AB: Our study focuses on the melt-poor, easternmost region of the Southwest Indian Ridge. We use a large set of off-axis bathymetry, gravity, and magnetic data (extending up to about 28 myrs-old lithosphere) to analyse accretionary processes and their evolution in time and along the ridge. We show that a significant proportion of the seafloor in our study area formed at a ridge that had no, or little volcanic activity, contradicting the view of all mid-ocean ridges as primarily volcanic systems. Axial volcanism appears controlled by punctuated events of focused magma supply, with dykes shooting out laterally into the ® a-volcanic ¯ regions. We also show evidence for large offset normal faulting (locally leading to the formation of corrugated surfaces), and for very persistent and extensive axial tectonic asymmetry (up to 25 myrs in a 100 km-long portion of the ridge). We use a sequence of kinematic reconstructions to discuss fault mechanisms, and the role of melt supply, spreading rate and ridge obliquity on ultra-slow accretion processes.
DE: 3035 Midocean ridge processes
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 8004 Dynamics and mechanics of faulting (8118)
SC: Tectonophysics [T]
MN: Fall Meeting 2005