HR: 09:00h
AN: V31F-05    [Abstracts]
TI: Does the Reunion Hotspot Volcano Emplace on a Fossil Ridge or a Fracture Zone?
AU: * Deplus, C
EM: deplus@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris et CNRS, 4, place Jussieu, Paris, 75005, France
AU: de Voogd, B
AF: Universite de Pau et CNRS, MIGP, Pau, 64013, France
AU: Dyment, J
AF: Institut de Physique du Globe de Paris et CNRS, 4, place Jussieu, Paris, 75005, France
AU: Depuiset, F
AF: Institut de Physique du Globe de Paris et CNRS, 4, place Jussieu, Paris, 75005, France
AU: Sisavath, E
AF: Universite de Pau et CNRS, MIGP, Pau, 64013, France
AU: scientific party, a
AF: N/O L'Atalante, Ifremer, Indian, Ocean,
AB: It is now clear that the structure and the mechanical properties of the lithosphere have to be taken into account to understand how mantle plumes are expressed by surface volcanism. Reunion, a large volcanic system in the Indian Ocean, is widely considered as the most recent expression of a mantle plume. Previous studies have suggested that it might be located above pre-existing lithospheric structures such as a fossil spreading ridge or a fracture zone. Cruise FOREVER (FORmation and Evolution of the Volcanic Edifice of Reunion) of R/V L'Atalante has recently surveyed the oceanic plate around Reunion Island in order to investigate possible relationships between the structures of the plate and the emplacement of surface volcanism. The cruise collected multibeam bathymetry and back-scatter data, as well as magnetic, gravity and 24-channel seismic reflection profiles. The coverage extends up to 250 km around the island. The new data confirm that the formation and evolution of the oceanic plate in the Reunion area is more complex than in the adjacent compartments. Oceanic magnetic lineations display various directions (discussed in Dyment et al., this meeting). In addition to the Reunion large volcanic edifice, the high resolution bathymetry coverage reveals numerous volcanic structures on the surrounding oceanic plate. Their morphology varies from elongated ridges to isolated seamounts. The seismic data, complemented by older multichannel seismic data (cruise REUSIS, 1993), allow investigations of the oceanic plate topography below the sedimentary cover. Preliminary results indicate that a fossil spreading axis is unlikely to underlie Reunion but reveal a N35° E topographic structure, possibly a short fracture zone. The seismic data also document the evolution of lithospheric flexure related to Mauritius and Reunion loading. FOREVER cruise scientific party : IPGP : Georges Boudon ; CNRS/IPGP : Christine Deplus, Jerome Dyment, Anne Le Friant ; Univ. Reunion/IPGP : Laurent Michon, Francky Saint-Ange ; Univ. Pau: Beatrice de Voogd; OPGC : Jean-François Lenat ; ENSG Nancy : Marine Perus ; IRD/Géosciences Azur : Bernard Pontoise
DE: 3025 Marine seismics (0935, 7294)
DE: 3037 Oceanic hotspots and intraplate volcanism
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 9340 Indian Ocean
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting