Soils on Carbonate Rocks of the Polar Urals: Genesis, Properties, and Classification

The genesis of poorly studied soils of the mountain-tundra landscapes formed on the eluvium of carbonate bedrocks and their colluvial derivatives in the Polar Urals has been clarified on the basis of soil macro- and micromorphological diagnostics and data on the soil physicochemical properties and chemical composition. The soil-forming fine earth is characterized by considerable heterogeneity because of different ratios of allochthonous and autochthonous materials overlying carbonate bedrocks. The organic matter of the soils is represented by a combination of several microforms of humus reflecting both modern (cryogenic, biogenic) and inherited features of previous stages of soil formation. Pyrogenic impacts on the soil are diagnosed by the abundance of charred plant tissues in horizons with highly ferruginous and charred organic matter and by the inclusion of carbonaceous crumbs inside the fractured fragments of carbonate bedrock. Soil formation in a warmer period of landscape development during the Holocene climate optimum is diagnosed by signs of dissolution and recrystallization of calcite in rock fragments. Specific relict features in modern soils are represented by clayey–humus–iron caps and films on rock fragments incorporated into the carbonate matrix and suggest that the soil-forming rock contains inclusions of paleosol fragments.