HR: 1340h
AN: T43A-1091    [Abstracts]
TI: Mid-Miocene to Present Growth and Uplift of Mt-Lebanon and Tectonic Evolution of the Dead Sea Transformê's Restraining Bend.
AU: * Elias, A
EM: elias@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Laboratoire de Tectonique 4 place Jussieu, case 89, Paris, 75005, France
AU: * Elias, A
EM: elias@ipgp.jussieu.fr
AF: National Center for Geophysical Research, 59, Rue Zahia Selman, P.O. Box 11-8281, Riad EL-Solh, Beirut, 1107 2260, Lebanon
AU: Tapponnier, P
EM: tappon@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Laboratoire de Tectonique 4 place Jussieu, case 89, Paris, 75005, France
AU: Sursock, A
EM: asursock@cnrs.edu.lb
AF: National Center for Geophysical Research, 59, Rue Zahia Selman, P.O. Box 11-8281, Riad EL-Solh, Beirut, 1107 2260, Lebanon
AU: Daeron, M
EM: daeron@gps.caltech.edu
AF: Tectonics Observatory, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, United States
AU: Jacques, E
EM: jacques@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Laboratoire de Tectonique 4 place Jussieu, case 89, Paris, 75005, France
AU: King, G
EM: king@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Laboratoire de Tectonique 4 place Jussieu, case 89, Paris, 75005, France
AB: The Lebanese Restraining Bend (LRB), principal irregularity along the left-lateral Dead Sea Transform (DST), is a ~25? clockwise inflexion of the Yammouneh Fault (Y.F.), through-going branch of the DST between Galilee and Syria. This is a region of high and broad relief, with the highest mountain range of the Levant (Mt-Lebanon, 3100m asl), whose east flank is truncated by the fault. Transpressional shortening is mostly taken up by a large, partly submarine thrust system ? the Mount Lebanon Thrust (MLT) ? that dips beneath the west flank of the range and is responsible for its growth and uplift. This flank is marked by the steeply west-dipping Lebanese Flexure, which warps a thick sequence of Mesozoic limestones, separating the uplifted, deeply incised, Mt Lebanon mega-anticline core from the flat narrow, coastal stretch. Such west-vergent, asymmetric folding is the surface expression of the crustal-scale MLT ramp, which extends for ~ 120 km from south to north. A well-developed foreland fold and thrust belt exists in northern Lebanon, and smaller-scale thrusting is observed along the southeastern flank of the range. Fieldwork helps constrain the onset and evolution of shortening and uplift. There is quantitative evidence that shortening started around 15-20My ago in the south, but not much before 5Ma in the north. Geological observations in central Lebanon suggest a Mid- to Late- Miocene age for the Flexure, with much of the mountain building postdating 13Ma. The bulk of uplift and largest amount of folding postdate the Late-Miocene (10-7Ma). At Kousba, the Flexure is of late-Miocene-Pliocene age, with much of the growth between the Messinian and Lower Pleistocene (7-2Ma). Folding, uplift and faulting along the northern foreland belt started after the end of the Miocene (5Ma), and continues today. The Qalhat, Tourbol, Bebnine-Miniara and Aabdeh ramp-anticlines thus provide a clear example of progressive stepping and migration of thrust ramps into a foreland basin. The timing of mountain building is in keeping with the inference that the Dead Sea Transform propagated northwards across the LRB, and implies that its main "Syrian" branch did not accumulate much offset prior to 5Ma.
DE: 8005 Folds and folding
DE: 8102 Continental contractional orogenic belts and inversion tectonics
DE: 8107 Continental neotectonics (8002)
DE: 8108 Continental tectonics: compressional
DE: 8111 Continental tectonics: strike-slip and transform
SC: Tectonophysics [T]
MN: 2007 Fall Meeting