Minerageny of modern continental carbonates in the Perm Region

Research subject. Deposits and occurrences of calcareous tufa, spring waters with a mineralization of more than 1 g/dm 3. Aim. Identification of the minerageny features of continental carbonate formation. Materials and methods. An analysis of the chemical composition of spring waters database compiled on the basis of hydrogeological surveys conducted in 1966–1992 at a scale of 1:200 000 in the Perm Region and the Catalogue of Deposits and Occurrences of Minerals of the Perm Region. Interpretation of the digital elevation model to identify neotectonic elements. Results. A mineragenic model of continental carbonate formation was reconstructed, including: (a) mobilization of calcium by underground waters on lifted blocks composed of carbonate-and-sulphate evaporites and groundwater discharge in adjacent trough blocks favorable for the slow flow of surface water; (b) essentially chemical deposition of subaqueous calcareous tufa at the site of groundwater discharge mainly biochemical precipitation of aquatic calcareous tufa in the lake, oxbow lakes and mean dering rivers, favorable for the activity of plants and living organisms. Conclusions. The zoning of calcareous tufa deposits on a neotectonic basis was carried out. The greatest contribution of sulphate calcium waters to the formation of calcareous tufa deposits was shown. The maximum possible quantity of chemogenic and biogenic calcium carbonate that can precipitate from individual springs in 100 years was calculated, amounting to 0.0001–1 million tons