Influence of Frasnian-Tournaisian reef massifs on halokinesis in the Solikamsk depression of the Pre-Ural trough

Research subject. Sedimentary strata of the Solikamsk depression of the Pre-Ural trough. The geological structure of the Solikamsk depression is characterized by the presence of a carbonate complex with a reef massif in the lower part of the sedimentary cover and a halogen stratum up to 500 m thick with salt uplifts formed in the roof in the upper part. The distance between the reef complex and the plastic salt strata ranges 1300–1700 m. Aim. Identification of the influence reef massifs on the formation of salt structures. Methods. Comparison and analysis of structural maps of the top of the reef-carbonate complex and the top of the salt strata, in the setting of the geodynamic conditions that existed at the border of the East European platform and the active Ural system. Results. One of the factors controlling the area distribution of salt uplifts of the Kungurian halogen sequence was established to be the presence of reef massifs in the Frasnian-Tournaisian sequence. Uplifts at the top of the salt mass are located in the spaces between the reef massifs. This is explained by the geodynamic influence of the capping structures of the reef massifs observed at the base of the salt strata. Uplifts in the base of the salt stratum under the action of general compressive stresses, due to its close position to the Urals, influenced the formation of a stress field in the plastic salt mass. As a result, the situation of a reduced mechanical stress in the areas between the enclosing structures of the salt mass developed. In these areas, during halokinesis, plastic salt masses were squeezed followed by formation of uplifts in the roof of the salt mass. Conclusions. In the Solikamsk depression, the capping structures above the Frasnian-Tournaisian reef massifs are a transmission link for the influence of the deep-seated strata on the plastic halogen strata located in the upper part of the sedimentary cover.

Pre-Ural trough, salt domes, reef massifs, structural plans