HR: 0800h
AN: T41E-1261    [Abstracts]
TI: Rifting to spreading processes in the eastern Gulf of Aden, the ENCENS project
AU: * LEROY, S
EM: sylvie.leroy@lgs.jussieu.fr
AF: Lab. tectonique CNRS UMR 7072 - UPMC, 4 place Jussieu Case 129, 75252, PARIS Cx05 France
AU: d'Acremont, E
EM: dacremont@obs-vlfr.fr
AF: Lab. tectonique CNRS UMR 7072 - UPMC, 4 place Jussieu Case 129, 75252, PARIS Cx05 France
AU: Tiberi, C
EM: christel.tiberi@lgs.jussieu.fr
AF: Lab. tectonique CNRS UMR 7072 - UPMC, 4 place Jussieu Case 129, 75252, PARIS Cx05 France
AU: Ebinger, C
EM: c.ebinger@gl.rhul.ac.uk
AF: Royal Holloway, Queen's building, Egham, TW200EX United Kingdom
AB: Existing academic and industry data from the eastern Gulf of Aden away from the Afar flood basalt province show that it is an ideal natural laboratory for seismic studies of passive continental margins because 1) the Gulf of Aden margins are largely free of salt deformation structures, and Oligocene-Recent sedimentary strata are relatively thin (< 4 km; Leroy et al. 2004; d'Acremont et al submitted); 2) the onshore and nearshore rift structures are well exposed, and have been mapped in details (e.g., Watchorn, 1998; d'Acremont et al., submitted); 3) Exploratory well data exist for stratigraphic ties; 4) Our study area is more than 1300 km from the proposed centre of the Late Oligocene Afar plume (e.g., Schilling et al., 1992), and isolated intrasedimentary volcanic occurrences should pose no problem to seismic imaging; 5) The Gulf of Aden is one of the few oceanic basins worldwide where the two conjugate passive margins can be reconstructed within relatively little uncertainty. A cruise, ENCENS II in 2006 (R/V L'Atalante), will be dedicated to multichannel seismic profiling and ocean bottom seismometers (OBS) deployment in order to image the crustal structure of the conjugate margins. To complete our view of this area, a detailed broadband seismic survey along continuations of the crustal-scale OBS seismic refraction/wide-angle reflection profiles in ENCENSII will take place onland in the Dhofar area (northern margin) and in the Socotra island (southern margin). This combination of methods will ensure we define crustal and upper mantle seismic velocity variations. We will then be able to constrain both the geometry of the Moho and that of the lithosphere-asthenosphere boundary, and yielding means to evaluate the current continental rifting and breakup models. We will integrate these unique seismic data with existing ENCENS-SHEBA offshore data and Dhofar Seismic Experiment data, bridging the gap between studies of young margins and extended continental rifts.
UR: http://gdrmarges.lgs.jussieu.fr
DE: 7294 Instruments and techniques
DE: 3025 Marine seismics (0935)
DE: 3035 Midocean ridge processes
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 3094 Instruments and techniques
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting