International Geologiical Congress - Oslo 2008

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STT-01 General contributions to tectonics and structural geology - Part 1

 

Tectonic evolution of the Levantine Area since the Mesozoic - Lebanese sector

 

Mustapha Mroueh, Lebanese University (Lebanon)
Catherine Homberg, Pierre et Marie Curie University (France)
Eric Barrier, Pierre et Marie Curie University (France)
Georges Aoun, Lebanese University (Lebanon)
Hassan Jaafar, Ministry of Energy and Water (Lebanon)
Rafic Hamzeh, Lebanese University (Lebanon)
Carla Muller, Free Lancer (France)
Fathi Hijazi, Lebanese University (Lebanon)
Walid Hamdan, Lebanese University (Lebanon)
 

 

Field studies were conducted in Lebanon since the year 2001.At least two field campaigns were achieved, in order to reconstruct the Meso-Cenozoic tectonic evolution of the Levantine domain. The studied areas were the central Mount Lebanon, which is a box-like anticline, and the Bekaa valley, which is an asymmetrical syncline. We aimed to recognize the periods of tectonic activity in Lebanon and to characterize as possible the deformation pattern and stress field, associated with each event. Both the pre-collusional tectonics (Mesozoic to Paleogene periods) and the collusional tectonics (Neogene to Quaternary) were investigated. Our observations indicate that the numerous N060◦ to N120◦ E faults of the Levant margin are normal faults and thus resulted from extensional tectonics. Their offset ranges from a few meters to a few hundred meters. Two main extensional events were recognized. The older occurred during Early Cretaceous. The direction of extension strikes N045◦ E in. The second period of extension occurred during the Eocene and Oligocene. It is a roughly trending N010◦ E extension evidenced in the whole studied areas. At Early Miocene, the tectonic context of the studied margin drastically changed. Our observations indicate that the folds of Ns to NWSE, the thrusts and the stike-slip faults are developed following a Neogene compressional and transgressional context. At Early Miocene, the collusion of the northern Levant margin with Eurasia is responsible of moderate folding in Lebanon, and characterized by a NW-SE to E-W compression. The late Miocene is marked by a radical change in the stress pattern that we related to the development of the transform boundary along the Levant margin. The final development of the Mount Lebanon, anti-Lebanon and the Bekaa syncline, probably occurred at that time. The initiation of the Levant fault induced a complex stress pattern, including the regional NNW-SSE compression.

Key words: Mesozoic, Cenozoic, Lebanon, Tectonic evolution, Levant, Strike-slip fault,

 

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