Soil-like formations of the Baikal rift zone diapir structures

The soils of the Barguzin north-west basin are formed in the area of the gas-hydrothermal fluids. The research was carried out in the area of the Kuchiger springs, on the shore of a swamp - a collector of hydrothermal waters. As the studies have shown, during the cold season, as a result of the formation of an ice "shell" on the surface of the swamp and the phase expansion of water during crystallization, horizontal ice pressure on the coastal positions occurs. The soil profile in the permafrost diapir zone undergoes significant transformations, which are expressed in turbation of layers, violation of their occurrence order, fragmentation into morphones, and mixing of the material. To compensate for the lateral pressure, the soil bulges upwards with the formation of extended coastal and offshore bars in the microrelief. At the same time, the surface permafrost, being impervious to gas emanations coming out in the swamp, forces them to unload, bypassing the ice plug, i. e., appearing near the coast, along cracks that occur during the collision turbations in the diapir bars. Thus, in addition to the physical cryogenic effect, the offshore bars experience (mainly during the cold period) thermal and chemical effects from passing gases. The described processes are morphologically manifested in the profile in the form of a large number of disordered interlayers, spots, vertical, near-vertical or horizontal stripes, wedges, fragments of soil layers, and etc. The studied soils are characterized by a wide range of variation in grain size composition, pH-values, ion activity, salinity, and humus content. The classical system of the compact horizons is preserved only on the coastal section of the profile (5,8 m). The alternation of humus and quasi-gley impregnated horizon is most typical on the 6,1-8 m segment. The most complex soil profile with numerous turbinations and morphones, various forms of organic matter and properties is formed in the collision zone, where maximum manifestations of permafrost and endogenous factors are observed (bar crest, length 9,5 m).