Formation of sedimentary materials in the permafrost regions cryolithogenesis

The most general and fundamental geological principles of the formation of sedimentary deposits in the permafrost regions are associated with the questions of grain-size distribution and chemical-mineral composition, structural-textural features and composition of the frozen sediments, the nature of which is elucidated in the course of study of chemical, physical-chemical and physico-mechanical processes that occur in the sediments of the permafrost regions in their stage-by-stage transformation. These questions are dealt with in works by B.I. Vtyurin, E.A. Vtyurina, Sh.Sh. Gasanov, I.D. Danilov, E.D. Yershov, Ye.M. Katanosov, V.N. Konishchev, Yu.A. Lavrushin, A.I. Popov, V.O. Targulyan, I.A. Tyutyunov, P.F. Shvet-sov, I.A. Shilo, P.A. Shumskiy et al. In general, sedimentary formations reflect a number of factors and processes of lithogenesis, the development and manifestations of which occur specifically under various geological and geographical conditions. Certain combinations of factors, conditions and processes of lithogenesis predetermine the composition, structure and properties of sedimentary formations. The idea was to distinguish specific and strictly definable types of lithogenesis.

As early as 1957, N.M. Strakhov distinguished types of lithogenesis as specific forms of the lithogenetic process at the stage of sedimentation and diagenesis, giving rise to the quite varied sum total of deposits. This author distinguished four types of recent lithogenesis, namely, ice, humid, arid and volcanogenic-sedimentary. The ice type of lithogenesis was defined by Strakhov as the cases when there was an ice cover on the soil surface and negative mean annual temperature; the humid type was defined by the intensity of degradational processes of organic matter; and the arid one by the intensity of evaporation, i.e. according to climatic attributes (air temperature and humidity). The volcanogenic sedimentary type is not of a zonal nature; it develops on the most mobile sites of the lithosphere which are the most permeable for magma. At present the majority of researchers emphasize the necessity to define one more type of lithogenesis - cryogenic. This is associated with the fact that in the cold regions at each stage of formation of sedimentary materials (i.e. at the stage of weathering, transfer, accumulation of sediments and diagenesis) the factors and processes of lithogenesis are characterized by such wide differences in a qualitative respect that in the long run they give rise to specific deposits which are the products of a specifically cryogenic type of lithogenesis. They are cemented with ice at negative temperatures and are characterized by a high content of silty (aleurolite) and sandy material as well as ice breccia and ice conglomerates. They also have a specific and unique cryogenic structure, which is that of sedimentary rocks, and a specific typomorphic complex of minerals and rocks (ice, hydromicas, montmorillonite, substances and compounds with oxides of ferrous iron, manganese and other elements, a specific complex of mineral deposits and the like).

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