Tectonics of the Soberbash Mountain (North-Western Caucasus)

Abstract

Relevance. For a long time, ideas about its vertical-fault-block structure prevailed for the territory of the folded-thrust structures of the North-Western Caucasus. Recently, there have been more and more publications describing dislocations formed in a tangential compression environment. However, these constructions do not always rely on a reliable factual basis, or they are not palinspastic, geometrically not reliable. In our work, the structure of the city of Soberbash is considered, where convincing evidence of the manifestation of powerful horizontal tectonic movements in the region has been found. Aim. Detailed study of dislocations exposed on the southwestern slope of Soberbash. Finding out their genesis. Methods. Collection of materials on the geological object under consideration during field observations. Documenting dislocations, photographing large fragments of the outcrop and its individual details. Sampling of rocks from above and below undeformed strata, as well as from individual folds inside the deformation zone and a thin-block matrix filling the space between them. Subsequent micropaleontological studies in the laboratory. To clarify the tectonic nature of dislocations, their structural analysis and comparison with the previously studied structures of the Crimea and the Northwest Caucasus were carried out. The materials of the satellite survey were used, which made it possible to clarify some fundamental issues of the tectonics of the region and the object directly studied. Results. A zone of abnormally complex tectonic deformations was found in the outcrop on the southwestern slope of Soberbash. The underlying sediments are represented by horizontally lying marls, limestones, sandstones. The overlapping layers lie sub-parallel to the underlying, consist of marls with thin layers of clay and sandstone. The conducted studies indicate that the zone of tectonic deformations is a large layer-by-layer breakdown in rocks of the same age, located at the base of a gentle tectonic cover. Mount Sober-Bash is interpreted by us as a tectonic outlier (clip). The significant thickness of the deformation zone (5 m) indicates the scale of horizontal tectonic movements. The morphology of dislocations indicates the movement of allochthon in a north-westerly direction. The section itself can be considered tectonotypic for fold-thrust dislocations formed during layer-by layer disruptions in a tangential compression environment.