Mapping of the geological and geomorphologic basement of landscapes under the level structure of relief for managing environmental risks within the southern cryolithozone

Abstract

The article considers the experience of large-scale mapping of the geological and geomorphological framework of landscapes, taking into account the layered structure of the relief. The key study site represented a 25 km² area, in the northern part of the Yenisei Ridge. This territory is located in the southern cryolithozone. In the course of field work, over a dozen transects were established. They reflected various structural levels of the relief, i.e., the products of its cyclic development. Surface deposits were studied using borehole cores, occasional natural outcrops, and soil pits. These data were supplemented with extrapolations from the analogous areas of the Yenisei Ridge. The collected material on relief features provided the basis for the development of landscape subdivisions’ hierarchy applicable for landscape mapping of territories with leveled denudation relief: the Yenisei Ridge, the west of the Central Siberian Plateau, and other regions with a similar history of development. The compiled map’s legend reflects the relief stratification and the main features of cover sediments. Two levels of planation surface and a complex of surfaces with superimposed planation and differentiation (three different landscapes) were identified. Periglacial processes in the Neo-Pleistocene (Q₂₋₃) glacial epochs and partially in the Holocene (Q₄) played the key role in the formation of the sedimentary cover. The main types of periglacial formations, wide spread within the study territory, were identified and included eluvial-desorption deposits (on summit areas), solifluction-desorption deposits (on slopes and ravine floors), and colluvium-alluvial deposits (on glacis floodplains). We have demonstrated that these types of surface deposits have differentiated influence on the distribution of permafrost geosystems. Analysis of the data on genesis of cover sediments and their relation to relief allowed us to extrapolate the results of the field studies and to map permafrost landscapes—the most susceptible to external impacts natural complexes that require targeted environmental policies.