HR: 09:15h
AN: V31F-06    [Abstracts]
TI: Do the Isolated Volcanic Islands of Mauritius and Reunion reflect a Thicker Underlying Lithosphere or a Weakening Reunion Hotspot for the last 10 Ma?
AU: * Dyment, J
EM: jdy@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris et CNRS, 4, place Jussieu, Paris, 75005, France
AU: Deplus, C
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: Sisavath, E
AF: Universite de Pau et CNRS, MIGP, Pau, 64013, France
AU: Depuiset, F
AF: Institut de Physique du Globe de Paris et CNRS, 4, place Jussieu, Paris, 75005, France
AU: scientific party, a
AF: N/O L'Atalante, Ifremer, Indian, Ocean,
AB: Reunion Island is the most recent expression of a hotspot which formed the Deccan Trap flood basalt, the Chagos-Laccadives Ridge (CLR), the southern part of the Mascarene Plateau (SMP), Mauritius and Reunion Islands. Whereas CLR and SMP are continuous structures, both Mauritius and Reunion Islands are isolated structures. Such an observation may reflect a thicker oceanic lithosphere under the Mascarene Islands, a weakening Reunion hotspot, or both. A related question for the Mascarene Islands is whether the rising hotspot material has used pre-existing structures of the oceanic lithosphere to reach the surface and create the volcanic edifices, or if the isolated islands reflect pulses in the hotspot activity. Recent bathymetric, magnetic and seismic data collected by R/V L'Atalante in 2006 as part of cruise FOREVER (FORmation and Evolution of the Volcanic Edifice of Reunion) help to address these questions. The full bathymetric coverage and the dense seismic survey allow the construction of a basement map that reveals a structure, possibly a short fracture zone, beneath the volcano (Deplus et al., this meeting). The magnetic anomaly map built from FOREVER and older reprocessed data displays coherent magnetic anomalies. Interestingly, the seafloor spreading anomalies can be deciphered under most of the edifice (radius ~ 100 km) with only an inner zone of radius ~ 50 km showing shorter wavelength anomalies related to the volcanic structures of the island. Anomaly 32, 31 and 30 are tentatively identified west of Mauritius, north and east of Reunion Island, and south of Reunion Island, respectively. The seafloor spreading lineations show two orientations, N120° E- N140° E and N90° E-N110° E in the central and eastern part of the compartment, respectively. These different orientations may be related to the presence of a triple junction trace which could have been the one connecting the Mascarene fossil spreading centre to the Southeast Indian Ridge.
DE: 3005 Marine magnetics and paleomagnetics (1550)
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