Modern Loess Formation as a Reflection of the Landscape and Climatic Conditions in the Selenga Middle Mountain Transition Zone

The relevance of the study lies in studying the genetic characteristics of loess sediments in the modern landscape and geochemical environment of the Selenga Middle Mountain transition zone. The distribution area of the loess sediments in this area coincides with that of the late Pleistocene permafrost zone. The permafrost zone here has a discontinuous and sporadic distribution with weathering processes occurring in a layer of long-term seasonally frozen soils. The object of the study is loess-like loams that are formed on watersheds and in landscapes adjacent to watersheds of the main ridges of the Selenga Middle Mountains. Sandy quartz grains morphoscopy revealed that matte and semi-rounded grains predominate. This indicates that during the final stage of their processing, the grains were exposed to subaerial (eolian) conditions. Conchoidal spalls and pits on quartz grains indicate that they were formed as a result of mechanical destruction of bedrock fragments and cryogenic weathering. Loess-like loams of the Selenga Middle Mountains are classified as syncryogenic subaerial sediments formed in the synchronicity of sedimentation and soil freezing processes.