--> --> The Late Miocene River Systems of the Eastern Mediterranean: Messinian Salinity Crisis, Sediment Input and Active Tectonics at a Plate Convergence Area

AAPG Africa Region, The Eastern Mediterranean Mega-Basin: New Data, New Ideas and New Opportunities

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The Late Miocene River Systems of the Eastern Mediterranean: Messinian Salinity Crisis, Sediment Input and Active Tectonics at a Plate Convergence Area

Abstract

This work shows an example of how syn-depositional active deformation changed sediment supply into the Levant-Nile area during the late Miocene. The tectonics of the Eastern Mediterranean involve subduction and widespread crustal-scale faulting and folding, and interact with three large river systems that dominated sediment supply at that time: Nile, Nahr Menashe and Eo-Sahabi. The Nahr Menashe had a vast extent into the deep Levant basin and was comparable in size to the Nile system, its catchment being located in the north/eastern hinterlands. This river system provided a source of terrestrially derived clastic sediments into the deep Levant basin, in addition to the Nile River and coeval to the Abu Madi Fm. We define the step-by-step evolution of the Nahr-Menashe fluvio-deltaic system from the end of Messinian salt deposition to the early Pliocene Mediterranean reflooding. The extensive seismic coverage allows an in-depth interpretation of facies and interaction with tectonic structures. In the northern Levant basin the river is entrenched over the active Latakia Ridge, where there is no Messinian salt. Tectonic structures are bypassed where basins are filled in by salt and flattened by the top MSC erosional surface. In the central Levant basin, the westward deflection of Nahr Menashe is caused by the topographic gradient on top salt. A backstepping transgressive final pattern is common to all three major rivers. The top-salt Nahr Menashe developed within a relatively short time window (5.55-5.33 My) and therefore it can be used as a time-marker, and as a tool to understand the relative timing of anticline development and thrust faulting in the area. Only the Nile survived the late Miocene Crisis; the Nahr Menashe starved due to plate-margin deformation and reconfiguration of its catchment. This changed the nature of sediment supply and potential clastic reservoirs in the Eastern Mediterranean since the early Pliocene.