HR: 0800h
AN: T41A-0352    [Abstracts]
TI: Crustal Geometry of a First Order Segment in the Northeastern Gulf of Aden Margin From Seismic Reflection (Offshore Oman)
AU: Autin, J
EM: autin@ccr.jussieu.fr
AF: Laboratoire de tectonique UPMC, case 129, 4 place Jussieu, Paris cedex 05, 75252, France
AU: * Leroy, S
EM: sylvie.leroy@lgs.jussieu.fr
AF: Laboratoire de tectonique UPMC, case 129, 4 place Jussieu, Paris cedex 05, 75252, France
AU: d'Acremont, E
EM: elia.dacremont@upmc.fr
AF: Laboratoire de tectonique UPMC, case 129, 4 place Jussieu, Paris cedex 05, 75252, France
AU: Beslier, M
EM: beslier@geoazur.obs-vlfr.fr
AF: Geosciences Azur OOV, B.P. 48, Villefranche/Mer ced, 06235, France
AU: Ribodeti, A
EM: ribodeti@geoazur.obs-vlfr.fr
AF: Geosciences Azur OOV, B.P. 48, Villefranche/Mer ced, 06235, France
AU: Bellahsen, N
EM: nicolas.bellahsen@lgs.jussieu.fr
AF: Laboratoire de tectonique UPMC, case 129, 4 place Jussieu, Paris cedex 05, 75252, France
AU: Razin, P
EM: razin@egid.u-bordeaux.fr
AF: EGID University of Bordeaux 3, 1, allée Daguin, Pessac cedex, 33607, France
AU: Robin, C
EM: cecile.Robin@univ-rennes1.fr
AF: Geosciences-Rennes University of Rennes I, Bat 15, Campus de Beaulieu, Rennes, 35000, France
AU: Grelaud, C
EM: grelaud@egid.u-bordeaux.fr
AF: EGID University of Bordeaux 3, 1, allée Daguin, Pessac cedex, 33607, France
AU: Al-Tobi, K
EM: kitobi@squ.edu.om
AF: University Sultan Qaboos, P.O Box 50, Al-Khod, Muscat, PC123, Oman
AB: The Gulf of Aden is an oceanic basin separating Arabia from Somalia. The rifting started 35 Ma ago followed by oceanic spreading from 17.6 Ma. The gulf orientation (N75°E) and the kinematics (about N30°E divergence) mark an oblique rifting where normal faults striking between N70°E (rift axis parallel) and N110°E (perpendicular to the divergence), are due to an extension direction probably evolving from N20°E to N160°E. The accurate 3D structure of the margins and the influence of structural inheritance or thermal and rheological evolution need to be better constrained. In order to answer this question, we mapped the 3D architecture of sedimentary units and tectonic features in the first-order segment between Alula-Fartak and Socotra Fracture Zones of the eastern Gulf of Aden continental margin. During the Encens cruise (Leroy et al., 2006) conducted in this area where the syn-rift structures are well exposed and covered by thin post-rift sediments onshore, multibeam bathymetry, 360 channels seismic reflection (10 km spaced profiles), gravity and magnetism data were gathered. Furthermore two reflection seismic profiles were processed with a pre-stack migration method. This excellent-quality dataset will permit us to image the structure of the margin and to reconstruct the 3D evolution from rifting to the onset of oceanic spreading. These results complement the field work realized onshore on conjugate margins (Oman and Socotra). The style of deposit seems completely different in the proximal and in distal parts of the margin. Indeed fault controlled syn-rift carbonate systems, well developed onshore, are not really well expressed offshore. The paleohigh seems to be preserved at the end of the rifting and filled by a thick syn-OCT and/or post-rift series. A late rifting or coeval to the OCT uplift seemingly sets going on the margin edge. Several seaward dipping normal faults cut the main escarpment of the last continental block, filled by small sedimentary wedges. The post-rift sequence covers all these features and the oceanic crust, also cut by several southward dipping normal faults. Refraction and seismological studies, providing MOHO depth, will constrain future lithospheric analogue models of oblique rifting.
DE: 0935 Seismic methods (3025, 7294)
DE: 8105 Continental margins: divergent (1212, 8124)
DE: 8109 Continental tectonics: extensional (0905)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting