--> --> The Mesozoic and Cenozoic Tectonic Evolution of the Eastern Mediterranean's Levant Basin: Interplay Between Inherited Structures and Regional Geodynamics Causing Basin Inversion

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The Mesozoic and Cenozoic Tectonic Evolution of the Eastern Mediterranean's Levant Basin: Interplay Between Inherited Structures and Regional Geodynamics Causing Basin Inversion

Abstract

The Levant basin is located at the boundary of three major tectonic plates in the Eastern Mediterranean region. The movement of the African, Arabian and Eurasian plates through time affected its geologic evolution since the Mesozoic. In the past few years, the Levant basin has seen major hydrocarbon discoveries. It became a typical frontier basin with limited dataset. This contribution sheds the light on the evolution of the Levant basin offshore Lebanon since the Mesozoic. Correlation with regional geodynamic framework and plate tectonic movements was accomplished by using available studies, and revealed the implication of regional events on the geologic history of the basin and its inversion. Data used consist of recently acquired excellent quality PSDM 3D seismic data covering about 3600 Km2 (courtesy of PGS and the Lebanese Ministry of Energy and Water). The investigated seismic surveys are located off the Lebanese coast, including the eastern margin of the Levant basin. Interpretation of this seismic dataset indicates the presence of a multitude of structures, mostly inherited from Early Mesozoic times and reactivated in the Late Miocene prior to the Messinian event. This reactivation is superposed on an earlier Late-Cretaceous and Eocene structures and caused by a regional NW-SE contractional stress field. Examples of those include NNE-SSW detachment anticlines folded during the Late Miocene. They are observed to overly pre-existing and inverted structures in the Mesozoic units. Other examples are onshore and offshore ENE-WSW normal and reverse faults reactivated into dextral strike-slip faults during the Late Miocene, in a bookshelf mechanism. Early Tertiary compression is evidenced offshore Lebanon by thrust faults close to the margin. They were active between the Eocene and Late Miocene, and currently sealed by the Messinian evaporite unit, indicating a cessation of shortening. The Oligo-Miocene unit contains a conspicuous layer-bound normal fault array, syn-sedimentary since the Early Miocene times. Their regular NW-SE orientation all over the basin might be caused by the presence of a strike-parallel NW-SE maximal horizontal stress in the Oligocene and Miocene. Their occurrence indicates a permutation of stress axes between the deep basin and the margin, as evidenced by the presence of extensive structures in the basin, while the margin shows compressional structures.