31 research outputs found
Atomic mechanisms for formation of localized nonequilibrium structural states in nickel under complex mechanical loading
No full textStability of localized nonequilibrium structural states in nickel under external loading
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PALE SOILS ON CARBONATE-FREE DEPOSITS IN CENTRAL SIBERIA AND THEIR TAXONOMIC POSITION IN THE SOIL CLASSIFICATION OF RUSSIA
No full textBased upon a comprehensive analysis of detailed descriptions of soil profiles and analytical data obtained by I. Sokolov, V. Zolnikov, L. Yelovskaya and other researchers, as well as upon data on the soil-forming factors, an attempt is made to determine the taxonomic level of pale undifferentiated neutral and slightly acid soils derived from carbonate-free deposits in the new classification system of Russian soils (versions 2004, 2008). The above group of soils is not uniform. According to their diagnostic morphological and physical-chemical properties the loamy permafrost-affected soils with ice-rich permafrost should be placed in the order of cryometamorphic or iron-metamorphic soils. The loamy sandy soils with dry permafrost may be placed in the same order. The soils with a shallow profile (< 30 cm) on hard parent rock should be qualified as members of the order of lithozems. The specific features of these soils make it possible to suggest new elements to the soil classification. A subtype of pale-metamorphized soils is offered to recognize the types of rzhavozems and raw-humus rzhavozems as the soils transitional to the pale soils. This suggestion is aimed at harmonization of a variety of ideas on the genesis, conditions for the development and nomenclature of soils, which permits us to give a more complete and reliable perception of the soil cover in the Central Siberian plateau
THE METHOD FOR IDENTIFYING THE MOST VULNERABLE AREAS CAUSED BY EXOGENOUS PROCESSES UNDER ARIDIFICATION/HUMIDIFICATION (BASED ON GIS AND RS)
No full textThe paper presents the method of identifying the most vulnerable territories under exogenous processes caused by aridification/humidification. It is based on the assumption that some forms and types of relief increase resistance of terrestrial ecosystems to external influences, while other kinds of relief make them vulnerable. The relationship between landscape and moistening (ground and climatic) is of great importance to plains which have groundwater close to the surface. We have used morphometric analysis to divide the territory into hydromorphic and automorphic landscapes. Hydromorphic territories are those that are affected by additional surface moistening and groundwater, while automorphic landscapes are less dependent on groundwater under normal atmospheric moisture. The territory is ranked according to the degree of vulnerability by expert evaluation method. The developed approach is based entirely on using GIS software (ArcGIS 10.2.1) and processing the DEM SRTM. As a result, two models of vulnerability of natural terrestrial ecosystems to exogenic processes on Baraba Plain (Western Siberia) have been created for both aridification and humidification cases. The opportunity to estimate the vulnerability is the novel feature for these models of terrestrial ecosystems, in both regional and local scales. The results obtained confirm the existing ideas about the discrete mosaic character of changes in spatial landscape patterns in the area under consideration. For the southern part of Western Siberia where farming is risky the assessment of the potential degree of vulnerability for ecosystems under conditions of increasing climate aridity and extremes is relevant
The Last Glaciation and Ice-Dammed Lakes in the South-East Altai
No full textThe palaeogeographic scheme of the distribution of glaciers and ice-dammed lakes in the Altai during the last global glaciation (MIS-2) was compiled based on a detailed large-scale geomorphological survey. Analysis of geomorphological traces of glaciers of this time indicates that they occupied smaller areas than those of the first Late Pleistocene glaciation. By this means, the ice dams created by them were smaller that resulted in small sizes of ice-dammed lakes. The preserved levels of terraces indicate that during the first Late Pleistocene glaciation in the Kurai-Chuya depression system the ancient lake was the only one with a level of 2250 m and a total volume of 1.70 km3. During the second Late Pleistocene glaciation in the south-east Gorny Altai, another separate lake existed which was the Bartal-Kurai Lake with a level of 1700 m and a volume of 45 km3. This lake was dammed by the Mashey Glacier, which descended from the northern slopes of the North Chuaya Range. In the Chuya Depression, the existence of a landslide-dammed lake with a volume of 0.7 km3 and a level 1.750 m has been found. Its formation was not associated with glaciers of the MIS-2 stage. Direct dating of the last ice-dammed lake in the Chuya Depression with a level of 1950 m and a volume of 140 km3 has not yet been determined. This lake was dammed by the Kuehtanar Glacier, which descended from the southern slope of the Kurai ridge. The volume of ice-dammed waters of the MIS-2 time was an order of magnitude smaller than it was in the first Late Quaternary glaciation. This explains the much lower intensity of erosive and accumulative processes associated with the mega-flood occurred due to the breakthrough of the lakes during MIS-2
Facies composition and stratigraphic position of the quaternary Upper Yenisei sequence in the Tuva and Minusa depressions
No full textThe paper concerns the sediment sequence, which is widespread in the Yenisei valley and in the Tuva and Minusa depressions and also present in the valleys of the southern Chulym plain. The sediments of this sequence were previously described as “Neogene mud-shedding”, as well as moraines, alluvial fan deposits, alluvium of Middle Pleistocene high terraces, and lacustrine sediments. The giant ripple marks on the Upper Yenisei terraces was commonly interpreted as ribbed moraines; however, in recent studies, these ridges have been repeatedly referred to as marks of giant current ripples. Besides, some recently published papers provide description of geology of this sequence fragments suggesting its deposition by cataclysmic floods. Geomorphological analysis of the area shows Pleistocene glaciers to have been localized within the medium–high mountainous areas. The glaciers did not reach the Tuva and Minusa depressions and occupied large areas only in the Todzha basin and on the periphery of the Darkhat basin, forming a glacial dam at its outlet, which resulted in glacial-dammed lakes filling the basin completely. These lakes outburst, and the resultant flooding led to the deposition of megaflood sediments, which we refer to here as the Upper Yenisei sediment sequence. A detailed analysis of its facies architecture revealed similarity of these sediments to those of the Sal’dzhar and Inya sequences in Gorny Altai. Most of the Upper Yenisei megaflood sediments are localized in topographic lows of the Tuva and Minusa depressions. Beyond the Altai–Sayan mountainous area, the megaflood sediments of the Upper Yenisei sequence compose high terraces of the Yenisei, Chulym, Chet’, and Kiya rivers in the southern Chulym plai
