Lithochemical Cyclicity of the Solikamsk Formation in the Southwestern Part of the Solikamsk Depression (Lower Permian, Perm Region)

New data on the lithochemistry of clayey–carbonate rocks of the Solikamsk Formation (Ufimian stage of the Lower Permian) in the southwestern part of the Solikamsk depression of the Ural foredeep are reported. The cyclicity of sedimentation was determined by the subsequent introduction of aluminosiliciclastic materials into the evaporite and marine basins from adjacent land. Based on variations of the terrigenous material, the Solikamsk Formation consists of nine cyclites, in which the content of clay minerals in the rock subsequently gradually increases and then relatively decreases. Some sulfate layers are not related to the distinguished cyclicity, but were formed through the diagenetic growth of anhydrite nodules on the groundwater level during periodical drying off the basin. Analysis of the chemical composition of the terrigenous component of the Solikamsk rocks made it possible to show that the basin at the beginning of Solikamsk time gained the destruction products of mafic rocks (data points are confined to the field “chlorite, smectite, and illite” in the IM–NAM diagram), while the end of this time was characterized by the influx of intermediate and acid material (decrease of HM and AM upsection, shift of data points of marls to the field of essentially illite clays with significant amount of K-feldspars in the IM and NAM diagrams). The different lithochemical maturity of delivered terrigenous material follows from the variations of CIA, CIW, and ICV indices.