Intra-salt deformation: Implications for the evolution of the Messinian evaporites in the Levant Basin, eastern Mediterranean

Abstract

We present new evidence of deformation features supporting a multiple deformation phase mechanism of the Messinian evaporites, through the interpretation of Pre-Stack Depth Migration (PSDM) seismic data including all intra-salt, base of salt (BS) and top of salt (TS) reflectors. The mechanism presented here involves a syn-depositional deformation event caused by a NW basin tilting during the last stage of the Messinian Salinity Crisis (MSC). This was followed by post-depositional differential sediment loading through radial spreading of the Nile Cone after the MSC. Inside the evaporite sequence, the upper intra-salt units may reside in a brittle domain with predominant thrust faults while the lower units in a ductile deformation domain with folds instead. A NW-flowing channel system is for the first time observed on the TS horizon, suggesting a northwestward basin depocenter during the TS formation. The observed NNW-NNE flow of the water bottom (WB) channels indicates the direction of the current basin depocenter, which suggests a dramatic clockwise shift during post-Messinian. A model of the Messinian evaporite evolution in the Levant Basin during the MSC has been established. The model is based on our observations and the detailed intra-salt interpretation, and is divided into four stages: a) the horizontal deposition of all the intra-salt units excluding the uppermost unit, b) the deposition of the uppermost unit and basin NW tilting occurred coevally or sequentially, c) the TS erosion and the development of NW trending TS channels and d) the deposition of post-Messinian sediments over the evaporite sequence.