ИСТИНА

Sedimentary strata that reveal elevated terraced surfaces, within the middle course of the Ob valley, can be classified into two types: 1) sedimentary strata with traces of cryometamorphic deformations; 2) sedimentary strata with the inclusion of boulder-pebble material. The study area belongs to the zone of island permafrost and migrations of the Arctic region and is located within 60 - 62 parallels of northern latitude. The occurrence of paleocryogenic deformations, their genesis and sedimentation conditions in the sections of the middle course of the Ob are debatable issues. The accumulation and formation of sedimentary strata occurred in the Neopleistocene time. The consequence of this genesis of the veins is their regular wedge-shaped form, clearly pronounced vertical banding and clear contacts with the host rocks. Cooling, aridization of climate in IIA 3, compared with previously existing epochs, led to a reduction in the level of the sea basin, which became an obstacle to the development of glaciation in the north of the West Siberian Plain and this contributed to the intensive freezing of rocks. The development of paleocryogenesis and, in particular, epigenetic ice contributed to wet conditions and developed extensive lake-marsh complexes.