Suchergebnisse

The scale of anthropogenic terrain transformation within the Norilsk industrial region was quantified and a classification of its consequences has been elaborated. The work is based on the results of 2021 expeditionary geomorphologic studies, interpretation and analysis of remote sensing materials and digital elevation models. It has been established that the total area of direct terrain transformation during the territory development was about 122,4 km2, and that of indirect transformation - 23,6 km2. The volume of anthropogenic landforms is at least 1,8 billion m3; accumulative forms account for 93% of the area and 72,6% of the volume of direct landform transformations. The types of anthropogenic landforms were identified, it was found that the largest area is occupied by embankments for industrial development and tailings, and the largest volume is characteristic of slope dumps. Indirect terrain transformation is mainly activation of gravitational processes, linear erosion, suffusion, thermokarst, heaving and deflation. The mass displacement of slope dumps by landslides or stone glaciers are the most dangerous for infrastructure facilities. Separate areas of indirect transformations are mainly limited to the lacustrine-alluvial lowlands and the bottoms of river valleys. Among them, the largest area (up to 20 km2) is occupied by segments of river valleys affected by spills of oil products and tailings. It has been established that the accumulation of pollutants in river valleys of the Norilsk industrial region occurs within the internal deltas and ice glades where the longitudinal slope decreases. Three stages of anthropogenic development of the territory are distinguished (I - 1920-1953; II - 1953-1986; III - 1986-2021); the most significant increment in the area of anthropogenic terrain occurred from 1953 to 1986. The average rate of anthropogenic terrain area increment over the past 36 years amounted to 0,81 km2/year. The highest rates of area growth are characteristic of the Kayerkan and Talnakh regions, which is associated with ongoing mining.

The study is based on the results of multibeam echo-sounding and high-frequency seismic profiling during the 2018-2022 cruises of the R/V "Akademik Nikolai Strakhov" and "Akademik Boris Petrov". Regular changes of morphometric parameters and the internal structure of pingo-like formations of the shelves of the Pechora and Kara seas were revealed. A morphometric analysis of pingo-like formations was carried out, which made it possible to draw conclusions about their relative age, as well as the role of near-bottom currents and slope processes in their modern dynamics. It was found that the density and morphological variety of pingo-like formations depend on the geological and tectonic features of the bottom area, the presence and nature of permafrost, the intensity of degassing, and the time of shelf flooding during the Holocene transgression. Pingo-like formations on the shelf, where the depth exceeds 70-80 m, emerged at the early stages of the Holocene transgression, and by now the permafrost there has largely thawed out. At the same time, pingo-like formations are still prominent in the relief and actively transformed by bottom currents, slope and, possibly, pseudovolcanic processes associated with ongoing degassing. Pingo-like formations are rare within shallow (up to 20-30 m) shelf areas close to the shore, and, apparently, continue their evolution at present. At the same time, the large thickness and continuity of permafrost prevent active fluid flow, acting as a seal. Pingo-like formations in the shallow-water zones are mainly cone-shaped mounds without intensive degassing. The density of pingo-like formations is maximum at the intermediate depths (from 20-30 to 70-80 m), in the presence of insular or discontinuous permafrost, under high fluid flow intensity within the fault zones and oil- and gas-bearing structures. Near-surface sediments in such areas are characterized by a combination of localized processes of heaving and active degassing. It predetermines a wide variety of the morphological types of pingo-like formations.Keywords: Arctic, bottom topography, degassing, pingo-like features, acoustic anomalies, multibeam echo sounding, seismoacoustic profiling

Based on the results of geomorphologic surveys carried out in 2021-2022 with the involvement of published materials, an original largescale (from 1:25 000 to 1:100 000) description of relief of urban areas of the Republic of Abkhazia (Gagra, Pitsunda, Gudauta, Noviy Afon and Sukhum) was compiled, and unprec-edented general geomorphologic maps were prepared, with morphogenesis-based legends. According to their morphostructure position and geomorphologic structure, the cities are grouped as follows: 1) completely lying in the area of the coastalmarine relief (Pitsunda and Gudauta); 2) located mainly within the sea terraces and erosion-denudation hills (Sukhum and Gagra); 3) completely located in the low mountains with a predominance of strongly dissected structural-denudation, fluvial and slope relief (Noviy Afon). A field survey revealed about 300 areas with unfavorable and dangerous geomorphologic processes within the urban areas, 44% of them are in Sukhum, 26% in Gudauta, 11% in Gagra, 10% in Pitsunda, 9% in Noviy Afon. The leading geo-morphologic hazards in all spectra are suffusion, erosion and biogenic processes. A list of other processes in a spectrum is predetermined by the geomorphologic position of cities. The widest range, which in addition to the abovementioned processes, includes also karst, mudflows and landslide processes (i.e. the most dangerous ones), is typical for urban areas with a complex relief structure, abundant in steep slopes and located within a narrow strip separating the spurs of the Main Caucasian Range from the sea (Gagra, Noviy Afon). The risk of destruction of street infrastructure (roadbed, communications, etc.) by dangerous geomorphologic processes was qualitatively estimated and its high dependence on the geomorphologic position of a particular section of the city has been established. In particular, the distribution patterns of recorded unfavorable and dangerous geomorphologic processes made it possible to state that the most favorable conditions for the construction and operation of urban infrastructure and buildings in general are within the leveled surfaces of the Late Pleistocene marine terraces, as well as the upper levels of floodplain terraces in the valleys of large rivers. Other levels of relief have certain disadvantages that impede the development of territories. Thus, the construction on the surface of the Holocene marine terrace is possible only if the foundations are waterproofed and soil is dumped in the lower areas. The development of high sea terraces, erosion-denudation and structural-denudation relief is difficult because of the high density of erosion dissection.