This paper presents a new approach to the analysis of the genetic nature of the mineral substance of loessial rocks. At the present time, the prevailing view on this issue is the eolian accumulation of loess, while the influence of other factors of formation has not been practically taken into account. However, loess accumulation can be explained by other mechanisms, e.g., active processes of cryogenic weathering under a very harsh climate. The latter concept is based on the results of analysis of wedge-shaped structures in loess thickness, as well as numerous data of spore-pollen, microfaunistic, and other types of analysis. Further developing concepts of loess formation, the authors made an attempt to assess the degree of influence of cryogenic processes on the composition and structure of loess. The proposed method is based on a differentiated analysis of the distribution of the main rock-forming minerals (quartz and feldspars) along the granulometric spectrum. Two criteria are proposed − the coefficient of cryogenic contrast and the heavy fraction coefficient (i.e., the coefficient of distribution of heavy minerals) − which allow determining the degree of participation of cryogenic processes, as well as aeolian and aqueous sedimentation, in the formation of loessial rocks. This method was used to study two sections of loessial thickness − in the south of the Russian Plain and within the Loess Plateau of China. The results of the study revealed the role of cryogenic factors in the formation of the composition of the loess horizons of soil-loess sequences of different territories. Particularly clearly the effect of cryogenesis was manifested in the loess section in the south of the Russian Plain. In the section of the Loess Plateau, only the youngest deposits of the last formation stage are affected by cryogenesis. It follows that not only within the long-term periglacial permafrost zone, but also under the conditions of seasonal freezing in the Pleistocene, the processes of cryogenic transformation of deposits could have developed, which contributed to the formation of the composition and properties of loess of sufficiently high thickness.

Multi-proxy studies of loess-soil sequences in the eastern Azov Sea region (Beglitsa‑2 section) and the northwestern Loess Plateau of China (Caoxian section) let us to suggest the correlation of the main stratigraphic horizons and to provide the comparison of landscape and climatic changes in these regions during the last interglacial-glacial climatic macrocycle. It was found that the Loess Plateau was characterized by a steady accumulation of loess during both glacial and interglacial epochs, when the so-called “warm” loess was formed. In the NE Sea of Azov region, the main loess accumulation corresponded to cryoarid conditions of the glacial phases, while during the interglacials, loess accumulation became ten times slower. The average sedimentation rate of loess material calculated for Caoxian section was more than 5 times higher than the one calculated for the Beglitsa‑2 section. Late Pleistocene paleosoils in the Beglitsa‑2 section are of the steppe type and correspond to the Salyn (MIS5e), Krutitsa (MIS5c), and Bryansk (MIS3) climate phases. Morphology of the Azov paleosoils is much better expressed than that of the paleosoils at Caoxian, where only the S1SS3 semidesert paleosoil (MIS5e) can be seen directly in the section. Climatic fluctuations in the southern East European Plain within the last interglacial-glacial macrocycle had significantly greater amplitude than that in the north-west of the Loess Plateau. In the latter, cryoarid glacial conditions alternated with warm semiarid interglacial conditions. In the northwestern Loess Plateau, the main climate dynamics was associated with the hydrological regime changes under the influence of the East Asian monsoon activity, which was at its lowest during the glacial stages (drier climatic phases) and increased during the interglacial and interstadials (wetter climatic phases).

Multi-proxy studies of loess-soil sequences in the eastern Azov Sea region (Beglitsa‑2 section) and the northwestern Loess Plateau of China (Caoxian section) let us to suggest the correlation of the main stratigraphic horizons and to provide the comparison of landscape and climatic changes in these regions during the last interglacial-glacial climatic macrocycle. It was found that the Loess Plateau was characterized by a steady accumulation of loess during both glacial and interglacial epochs, when the so-called “warm” loess was formed. In the NE Sea of Azov region, the main loess accumulation corresponded to cryoarid conditions of the glacial phases, while during the interglacials, loess accumulation became ten times slower. The average sedimentation rate of loess material calculated for Caoxian section was more than 5 times higher than the one calculated for the Beglitsa‑2 section. Late Pleistocene paleosoils in the Beglitsa‑2 section are of the steppe type and correspond to the Salyn (MIS5e), Krutitsa (MIS5c), and Bryansk (MIS3) climate phases. Morphology of the Azov paleosoils is much better expressed than that of the paleosoils at Caoxian, where only the S1SS3 semidesert paleosoil (MIS5e) can be seen directly in the section. Climatic fluctuations in the southern East European Plain within the last interglacial-glacial macrocycle had significantly greater amplitude than that in the north-west of the Loess Plateau. In the latter, cryoarid glacial conditions alternated with warm semiarid interglacial conditions. In the northwestern Loess Plateau, the main climate dynamics was associated with the hydrological regime changes under the influence of the East Asian monsoon activity, which was at its lowest during the glacial stages (drier climatic phases) and increased during the interglacial and interstadials (wetter climatic phases).

The article describes a new approach to analysis of the genetic nature of mineral matter of loess soils. The proposed method is based on differential analysis of distribution of the main bedrock-forming minerals (quartz and feldspars) by the granulometric spectrum. The author proposes two criteria such as the cryogenic contrast coefficient and heavy minerals distribution coefficient which allow to determine the role of cryogenic processes, aeolian and water sedimentation in development of loess soils. Ключевые слова: лессовые породы; гранулометрический состав; минералогический состав; криогенез; криолитозона; перигляциальная зона; историко-генетический подход.

Laboratory tests on isotopic composition of water and ice in structure-forming soils were carried out. The results of the tests have shown that the interactions between water and soils, water migration, and ice formation during the freezing process cause isotope fractionation influenced by soil composition and freezing conditions.

26 августа 2009 г. исполнилось 100 лет со дня рождения профессора Г.К. Тушинского (1909-1979). В статье кратко изложен его жизненный путь и основные достижения в науке и воспитании новых поколений специалистов.