Vol. XXVII, No. 3 (May – June 2023)
Full issue:    EC_3_2023_eng_opt.pdf

CONTENTS

CRYOLITHOGENESIS

  • Bazarova E.P., Kadebskaya O.I., Rubtsova M.N., Korotchenkova O.V., Kononov A.M. Cryogenic rapidcreekite of the Malaya Nizhneudinskaya cave (Eastern Siberia)
    Abstract
    The morphology and mineral composition of cryogenic formations of the Malaya Nizhneudinskaya Cave have been studied by electron microscopy and X-ray powder diffraction. This cave is confined to permafrost. The temperature in the cave is near zero all the year round, so that ice formations are widely developed. When solution freezes, and the subsequent partial sublimation of ice takes place, speleothems with cryogenic cave minerals are formed. Cryogenic formations are composed of gypsum, calcite, and a rare mineral rapidcreekite Ca2(SO4)(CO3)⋅4H2O. Rapidcreekite forms radial fibrous aggregates of acicular crystals of up to 200 mm in length. In our opinion, the source of sulfur is represented by the locally developed interlayers of gypsum in the non-karsting rocks overlying the limestones. This is the second finding of rapidcreekite in the speleo-cryomineralogenesis environment in the world and the first discovery of this mineral in the caves of Russia.

GEOLOGICAL CRYOGENIC PROCESSES AND FORMATIONS

  • Tarbeeva A.M., Efremov V.S., Lebedeva L.S., Shamov V.V. Erosional processes in small tundra catchments in the North of Yakutia
    Abstract
    Erosion plays an important role in removing permafrost degradation products. In order to identify the rates and mechanisms of erosion in degrading permafrost, fluvial landforms in small catchments at the foothills of the Kharaulakh Ridge were typified, and their morphology, formation conditions, and dynamics for 2019–2022 were characterized. The most dynamic landforms associated with melting ice wedges are thermokarst runoff hollows (water tracks), potholes, and thermoerosional gullies. Thermoerosional gullies forming in sediments without wedged ice grow upon very high floods; in the rest of the time, their sides slowly slide down under the action of snowfields. Sediments from gullies and potholes are deposited in the upper reaches of small rivers. The channels of small rivers are relatively stable, which is also typical of other permafrost regions. Differences in the dynamics of erosional landforms can be explained by an increase in the thermal rather than mechanical impact of water on frozen deposits, which is observed with the rise in air temperature against the background of relatively stable precipitation in the north of Yakutia.

SURFACE AND GROUND WATERS IN TERRESTRIAL PERMAFROST REGION

  • Konovalov V.G. Сharacterisrics of glacial feeding of rivers
    Abstract
    Regional calculation of the hydrological regime of glaciation includes the determination of long-term changes in glacial runoff and glacial feed in river basins of the Northern Hemisphere. For the Rhone River basin, monitoring data on glaciation parameters over the period of 1971–2016 and long-term data on precipitation and air temperature at weather stations of Switzerland were used for hydrological and glaciological calculations. The results of linear extrapolation of spatiotemporal changes in the altitude-area characteristics of the classified groups of glaciers proved to be sufficient for calculating the hydrological regime of glaciation. An adequate description of seasonal and long-term glacial feeding of rivers should take into account variations in the ablation of glaciers depending on the five types of active glacier surface and their altitude-area characteristics. Satisfactory absolute and relative estimates of differences between the measured runoff and the precipitation, evaporation, and glacial feeding in the upper Rhone River in 1971–2010 (Porte du Scex gauging station), as well as between the measured and calculated annual precipitation in the Rhone River basin for 1971–2016, were obtained.

    SNOW COVER AND GLACIERS

  • Mavlyudov B.R. Moulins: formation and significance
    Abstract
    The causes and conditions of the formation and changes of moulins are considered on the basis of author’s own data and literature sources. Moulins can be formed above the water level in crevasses in glacier ice and cannot be formed below the water level. A cylindrical shape of the moulins is associated with splashing of water jets at a certain depth from the glacier surface. The issues related to different mechanisms of the formation of moulins, their depth, age, and water level fluctuations are discussed. A possible connection of moulins with the internal drainage system of glaciers is shown. The relationship between moulins and thrusts in the glacier ice is specially considered, because there are glaciers, in which water does not penetrate to the glacier bed through the moulins.

CLIMATE AND CRYOSPHERE

  • Fedorov V.M., Frolov D.M., Agafonova E.A. Changes in the Earth’s insolation during the Holocene
    Abstract
    Variations in the Earth’s insolation by latitudes and seasons in certain periods of the Holocene are considered. A comparative analysis of insolation in boundary years of geochronological periods with modern insolation (2022) is carried out. The change in summer insolation in the hemispheres is analyzed separately. Quantitative estimates of changes in the intensity of insolation in the Holocene are assessed with respect to the modern insolation. The extremes of summer insolation in the Northern hemisphere are synchronized with the global paleogeographic events of the Holocene: the transition from the cold Pleistocene epoch to the warm Holocene and the Little Ice Age. It is shown that the change in the summer insolation of the Northern hemisphere is controlled by the characteristics of the Earth’s orbital motion and is a factor of the noted global paleogeographic events that took place predominantly in the Northern hemisphere.

ADVERTISING

  • Production of equipment for geotechnical monitoring