HR: 11:50h
AN: T42B-07    [Abstracts]
TI: Seismic Evidence for Neogene and Active Shortening Offshore Lebanon (SHALIMAR Cruise)
AU: * Carton, H
EM: carton@ipgp.jussieu.fr
AF: Equipe de Geosciences Marines, Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AU: Singh, S C
EM: singh@ipgp.jussieu.fr
AF: Equipe de Geosciences Marines, Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: Equipe de Tectonique, Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AU: Elias, A
EM: elias@ipgp.jussieu.fr
AF: Equipe de Tectonique, Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AU: Elias, A
EM: elias@ipgp.jussieu.fr
AF: National Center for Geophysical Research, P.O. box 11-8281 Riad El-Solh, Beirut, 1107 2260, Lebanon
AU: Briais, A
EM: anne.briais@dtp.obs-mip.fr
AF: Laboratoire de Dynamique terrestre et planetaire, Observatoire Midi-Pyrenees, 14 avenue Edouard Belin, Toulouse, 31400, France
AU: Sursock, A
EM: asursock@cnrs.edu.lb
AF: National Center for Geophysical Research, P.O. box 11-8281 Riad El-Solh, Beirut, 1107 2260, Lebanon
AU: Jomaa, R
EM: rjomaa@cnrs.edu.lb
AF: National Center for Geophysical Research, P.O. box 11-8281 Riad El-Solh, Beirut, 1107 2260, Lebanon
AU: King, G C
EM: king@ipgp.jussieu.fr
AF: Equipe de Tectonique, Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AU: Daeron, M
EM: daeron@ipgp.jussieu.fr
AF: Equipe de Tectonique, Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AU: Jacques, E
EM: Eric.Jacques@eost.u-strasbg.fr
AF: Institut de Physique du Globe de Strasbourg, 5 rue Rene Descartes, Strasbourg, 67084, France
AU: Barrier, L
EM: barrier@ipgp.jussieu.fr
AF: Equipe de Tectonique, Institut de Physique du Globe de Paris, 4 place Jussieu, Paris, 75005, France
AB: Lebanon is located on a 160 km long transpressional bend of the left-lateral Levant (Dead Sea) Fault. The main objective of the SHALIMAR (2003) marine survey was to characterize and map active deformation offshore Lebanon using a range of geophysical techniques, particularly seismic reflection profiling. The cruise results clearly establish the presence of submarine thrust faults - likely the source of one of the most devastating submarine historical earthquakes that happened along the Levantine shores - and clarify the structure of this part of the Levant margin. A submarine fold-belt, bounded by thrusts and lateral ramps and extending in places to at least 30 km from the shoreline, is interpreted as the foreland thrust system of the actively growing Mount Lebanon range. There is no large fault extending into the Levant Basin towards Cyprus, which indicates that thrusting only absorbs local transpression resulting from the Lebanese restraining bend. Both the Miocene and Plio-Quaternary sedimentary sequences are affected by shortening, with landward-dipping blind thrusts and associated growth strata. The presence of the Messinian evaporites creates complex deformation patterns, including normal faults due both to folding accommodation and gravity spreading, all well imaged in the seismic reflection profiles. Because the evaporite layer acts as a decollement level, deformation extends farther out seawards through a series of thrust imbricates or duplexes. Shortening is strongest between Beyrut and Batroun and decreases towards the south between Saida and Tyre. North of Tripoli, the passive margin is not affected by Neogene deformation, and is well preserved. We propose that, since the Miocene, the northward propagating Levant Fault interacted with margin structures inherited from the Mesozoic rifting phase, and was deviated away from the more rigid oceanic crust flooring the Levant basin, a process which led to the formation of the Lebanese restraining bend, and consequently to the offshore shortening we document here. Such coastal transpression has resulted in inversion of a ~100 km long segment of the passive margin, which might eventually evolve into a new subduction zone.
DE: 3025 Marine seismics (0935, 7294)
DE: 8005 Folds and folding
DE: 8107 Continental neotectonics (8002)
DE: 8111 Continental tectonics: strike-slip and transform
SC: Tectonophysics [T]
MN: 2007 Fall Meeting