Solonetzes of the earth faults zones in the north of the Barguzin depression (Buryatia, Russia)

In the northern part of Buryatia, atypical for the forest-steppe zone highly saline soils are formed, which are of the solonetz type. They are locally distributed and confined to steppe high floodplains or first above the floodplain terraces. Saline soils are located under the influence of thermal mineral waters of the Kuchiger spring. Studied soils are underlain by permafrost, cryoturbated, saline, gypsum containing, and of clay differentiation profile. Soils are formed on a fairly uniform lithologic substrate. Hydromicas of biotite (trioctahedral) type, regular mica-smectite interstratification (rectorite), chlorite, and kaolinite are identified at depths of 54-115cm. Solonetz process is characterized by the destruction of clay minerals of the rectorite type, relative enrichment with chlorite and hydromica of the biotite type. In the illuvial part of the profile (20-54 cm), the main components of the fraction less than 1 μm are hydromica of the biotite type, chlorite and highly irregular mica-smectite formation. Solonetz process led to a change in the structure of packages alternation, transformed the rectorite (regular interstratification) into irregular mica-smectite formation with different packages segregation of micaceous and smectite type. The studied soils are of mixed predominantly sulfate calcium-sodium salinity chemistry. Process of strong salinity is associated with a number of factors the main one is the additional source of readily soluble salts from unloaded Kuchiger hydrothermal waters. Salt retention in the soil profile is largely connected with permafrost. Solonetz soils of the earth fault zones are characterized by dark-humus accumulation of organic matter and alkali-clay differentiation of the profile.