Multiphase deformation of a multilayered salt giant: Salt tectonics in the Levant Basin

https://doi.org/10.1130/B38116.1
2025-06-06
GSA Bulletin
Jimmy Moneron, Zohar Gvirtzman

The Mediterranean salt giant deposited during the Messinian salinity crisis (5.97−5.33 Ma) is the youngest known example of its kind on Earth. Unlike older layered evaporite sequences, which typically become gravitationally unstable and pierce through overlying formations, the Mediterranean salt remains relatively undeformed at shallow depths, with its internal stratification largely preserved due to minimal postdepositional deformation. This provides an opportunity to study the early stages of salt deformation. Still, the restoration of a repeatedly deformed multilayered sequence remains a challenge, even when original stratigraphic markers are identified. To reconstruct the history of deformation, one needs to distinguish between the various deformation phases and restore the evolving structures in sequence. In practice, such a restoration is rarely possible because kinematic markers (vectors) are nearly impossible to observe after multiple overprinting deformation phases. The strength of this study is rooted in the comprehensive regional mapping of a diverse array of faults and fold crests across five stratigraphic levels. This detailed mapping revealed several dominant deformation groups, shedding light on the tectonic processes at play. By assuming that the gliding direction was approximately perpendicular to the azimuth of the faults and the fold crests, and that asymmetric verging folds hint at the direction of motion, we inferred the kinematic patterns. Additionally, our analysis of crosscutting relationships, truncation features, and variations in syntectonic thickness allowed us to reconstruct a chronological sequence of deformation events. This study identified and chronologically constrained multiple deformation phases of the Messinian salt in the Levant Basin, providing new insights into both syn- and postdepositional kinematics. Our basinwide analysis underscores the key roles of regional tilting, buttressing structures, and differential sedimentary loading in controlling salt flow. Based on an extensive three-dimensional seismic reflection data set, this work presents the first high-resolution salt tectonic analysis of its scale, advancing understanding of early-stage halokinesis and setting a benchmark for future global research in sedimentary basins.