--> Miocene Normal Faulting in the Levant Basin: A Spectacular Exemple of Compaction/Tectonic Interaction

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Miocene Normal Faulting in the Levant Basin: A Spectacular Exemple of Compaction/Tectonic Interaction

Abstract

The northern part of the Levant basin is located between two major transpressive plate boundaries: the Levant Fault System to the east and the Cyprus arc to the northwest. It is however affected by a dense array of normal faults. The detailed analysis of recent 3D PSTM/PSDM surveys provided by Petroleum Geo-Services (PGS) and the Lebanese Ministry of Energy and Water are used to solve this paradox, shedding light on the interaction between compactions and tectonic stresses. First the dating of these normal faults provide key arguments about their origin. The standard interpretation of the seismic data demonstrates that they are layer bound in an Oligo-Miocene unit. Their impact on stratigraphy unambiguously supports a syn-sedimentary activity during Early Miocene. The geometric relationship between these faults and transpressive structures (faults and folds) also demonstrates that these faults are synchronous with NW-SE compression along the margin. To further study the mechanical origin of these faults, throws were carefully mapped for tens of them. Most of the throw maps show two points a nucleation for faults striking parallel to the maximum horizontal principal stress. They are clearly vertically restricted. Looking at their strikes, they are very constantly oriented around N100 for fault affecting the lower Miocene and more random in the northern most part in the Oligocene units. All these observations, suggest that these normal faults were created as polygonal faults strongly interacting with a compressive tectonic regime. This is the first time that such an observation is made at basin scale. The mechanical implication of this result is further discuss in light of basin models available for this area.