Abstract: Holocene ice wedge structures in the arctic tundra in the Tambey river valley and in the Belyi Island are the subject of the study. The author studies the pollen spectra in the ice wedges and surrounding sediments and their chemical composition. To substantiate paleograhic reconstructions, the author analyzes radiocarbon datings of the Holocene sediments from the studied areas and the surrounding territories. Pollen analysis is the main research method. Adjacent sediment samples have been studied according to the standard procedure, but without acetolysis mixture. Pollen has been extracted using the simplified method due to low pollen concentration. The main result of the study is the systemization of the data of palynological analysis of Holocene ice wedges located in the zone of sea-level changes' imact. The author shows that ice wedges in the Tambey River valley had been accumulated from precipitations and because of the inundation by marine water. Ice wedges in the first marine terrace of the Belyi Island are characterized by the abnormally high concentration of marine salt, but the salinization is caused by ice wedge formation on the sides of remnant shallow saline lakes, not by sea-level changes.

Keywords: climatic fluctuations, peat, Holocene, pollen spectra, ice wedge, radiocarbon age, Yamal Peninsula, local pollen zone, sporo-pollen charts, North-West Siberia

Abstract: The paper contains the results of the hydrological generalization of the features of river ice regime of the Arctic zone of Western Siberia. The rivers under study (Nadym, Pur, Taz, the lower Ob and others) flow in swamped lowland in the area of permafrost, which defines the peculiarities of their hydrological conditions. The author studies the ice regime of navigation and ice crossing on these rivers. Special attention is given to the characteristics of the level regime in the period of ice phenomena, which helps define the danger of ice-related floods. The research is based on the data of 40 stage gauges from the start of measurements to 2014. The author demonstrates the patterns of special distribution of the main characteristics of the ice regime, determined by the dependence of average values on the geographic latitude of the studied areas. The author considers regional peculiarities of the conditions of ice level growth during the ice formation period and defines the floodable inhabited areas. 

Keywords: the Arctic, ice-related flood, ice thickness, ice break, freezing, river ice conditions, Ob, Nadym, Pur, Taz

Abstract: The Chukchi Peninsula or Chukotka Peninsula at about 66° N 172° W, is the eastmost peninsula of Asia. Its eastern end is at Cape Dezhnev near the village of Uelen. It is bordered by the Chukchi Sea to the north, the Bering Sea to the south, and the Bering Strait to the east. Most of the Chukchi Peninsula is occupied by highlands up to 1000 m a.s.l height. Lowlands are found, as a rule, near large lagoons. The main features of the area (from Anadyr' town to Lavrentiya) are represented by a slightly hilly relief formed by fluvial erosion and marine abrasion of the Mesozoic blocks. For the determination of the ion composition of ice wedges, ice samples were taken both horizontally with an interval of 10-12 cm and vertically with an interval of 10-15 cm. The ion composition of the ice was analyzed by ion chromatography method in the geochemistry laboratory of the Department of Landscape Geochemistry and Soil Geography of the Faculty of Geography of Lomonosov Moscow State University on the ion chromatograph "Stayer". The detection limit for chloride ion was 0.02 mg / l. The hydrochemical composition of snow, rivers and lakes water, segregated ice and partly of ice wedges was carried out in the hydrochemical laboratory of PNIIIS by acid-base titration. Continuous permafrost occurs everywhere beneath the ground surface. Taliks (up to 30-40 m thick) often occur underneath the largest thermokarst lakes and in the and under the lower reaches of large rivers. The temperature of the permafrost averages -10 ° C in the axial parts of the mountain ridges and -4 ... -6 ° C in river valleys and on the coasts. The thickness of the permafrost varies from 500-700 m in the highest parts of the ridges to 200-300 m in the interior valleys.

Keywords: peatbogs, segregated ice, salinity, marine coast, lake floodplaine, ions, mineralization, the Holocene, ice wedge, radiocarbon age

Abstract: The author shows that the purpose of cyclocryostratigraphy is to determine, characterize and interpret periodic or quasiperiodic variations in the cryostratigraphy of permafrost sections (mainly syncriogenic ones) and their use for refining the features of the formation of permafrost. The author formulates the concept of cryocyclitis as a complex of permafrost layers and their associations with ice wedges, characterized by the direction and continuity of the change in the cryostructures properties of the ground ice and its surrounding sediments, reflected in the location of the boundaries between them, which can be seen in a vertical section (in a borehole, outcrop, bore pit, etc.). The main research methods are the radiocarbon, stable isotope and geochemical ones. The study shows that often in the yedoma strata individual cyclites duplicate each other, thus demonstrating a continuous process. The author performs the cyclocryostratigraphic research of the structural features and development of the Late Pleistocene syngenetic ice wedge in the cyclical yedoma of the Asian Arctic: Western Siberia, Yakutia, Chukotka, Novosibirsk Islands, Alaska and northern Canada.Three cycles can be distinguished in the development of syngenetic ice wedges. Microcycles result from the changes in active-layer depth and the accumulation of a thin sedimentlayer over several years. Their vertical scale varies from centimetres to tens of centimetres, and their formation time ranges from one to hundreds of years. Mesocycles result from a change in the lake water level if ice-wedge formation took place on the banks or beneath shallow water. The vertical scale of mesocycles is a few metres, and their timescale usually varies from several hundred to a few thousand years. Macrocycles relate to a major change in the sedimentationregime or rarely – and mostly at the southern border of ice-wedge formation – with major climatic oscillations. The vertical scale of macrocycles numbers tens of metres, and their duration varies usually from many tens to sometimes hundreds of thousands of years.

Keywords: geo-cryo-cycles, Cryostratigraphy, Chronostratigraphy, yedoma, isotopes, radiocarbon, Late Pleistocene, macro-cycles, meso-cycles, micro-cycles

Abstract: The subject of the study is the distribution of oxygen and hydrogen stable isotopes and the variations of the deuterium excess in snow and glaciers of the Polar Urals and massive ice of the south of the Yamal Peninsula and the coast of Baydaratskaya Bay. The isotope composition of winter snow and ice of the glacier No. 1, and the glacier of the Romantics was studied in the Polar Urals. On the south of the Yamal Peninsula, the isotopic characteristics of the massive ice in the valley of the Erkutayakha River, Oyuyakha River and at the mouth of the Sabettayakha River were analyzed. The massive ice of the autochthonous type should differ significantly in the isotopic composition of the ice from the buried ice. Isotopic characteristics of massive ice are a good tool for studying the conditions of the ice formation, which is due to the processes of isotope fractionation of oxygen and hydrogen during phase transitions, while the fractionation factor of vapor-water and water-ice transitions are determined by temperature. Variations of stable isotopes of oxygen and hydrogen in massive ice and the δ2H -d-excess ratio are used as a diagnostic tool to determine the type of ice formation. In winter snow of the Polar Urals higher values of isotope composition is recorded with depth increase, reflecting the seasonality of snow accumulation. Very high values of the deuterium excess are recorded - from 14.3 to 19 ‰, the average value was 16.9 ‰. Values of the deuterium excess are distributed in antiphase with the distribution of heavy oxygen and hydrogen with depth. The values of δ18О in the ice of the glacier №1 range from -12.6 ‰ to -16.03 ‰, δ2H - from -96.7 ‰ to -115.1 ‰. The values of the deuterium excess in the ice of the glacier No. 1 are rather low, averaging 6-7 ‰, the highest value of d-excess is 13.1 ‰ the minimum value of d-excess = 4.7 ‰. For glacier ice No. 1, a negative slope δ2H-d-excess is noted, indicating congelation ice formation in a closed system (i.e., a limited volume of water). This can occur when a certain volume of thawed water in pores of the firn, when the firn mass, saturated with thawed water, turns into ice. The Romantik Glacier occupies in δ2H-d-excess ratio an intermediate position between the atmospheric precipitation (snow cover) and the ice of the glacier No. 1.Variations of stable isotopes of oxygen and hydrogen in the massive ice on the Erkutayaha River in the southern part of the Yamal Peninsula are significant, and the δ2H-d-excess ratio is an evidence of mostly intra-soil injection ice formation, i.e. freezing of a limited volume of free water. The δ2H-d-excess ratios for massive ice at the mouth of the Oyuyakha River at the coast of Baydaratskaya Bay evidences that a powerful ice body could have been formed when a large volume of water was frozen in a closed system, as can be seen from the trend of decreasing of δ18O values down from the top. The non-explicit expression of the negative correlation of δ2H to d-excess may be due to the fact that the source of moisture was the surface water evaporated, or was characterized by less isotope fractionation than the theoretical one. The values of d-excess in ice are from 8.4 to -2.3 ‰ and indicate rather the intra-soil formation of ice. Variation of the δ2H-d-excess ratio in ice formation is an additional tool for diagnostic studies of massive ice genesis and types of ice formation.

Keywords: Polar Ural, intrusive, segregated, deuterium excess, hydrogen isotopes, oxygen isotopes, ice, glacier, snow, Yamal Peninsula

Abstract: The subject of the study is the Late Pleistocene and Holocene syngenetic ice wedges of the Mamontova Gora and Syrdakh outcrops and the reconstruction of winter temperatures of ice wedge formation periods. The main study objects are ice wedges over 7 m high in the upper part of the 50-60-meter heigh terrace of the Mamontova Gora, the ice wedges are surrounded by the 9-12 m thick lacustrine loamy sediments. The Holocene and modern ice wedges on the high flood plain of the Aldan River are also studied. In the thermoerosine ravine near Lake Syrdakh the Late Pleistocene ice wedges were also studied. The main research methods are the mass-spectrometry analysis of the oxygen and hydrogen isotope composition of the Late Pleistocene, Holocene and modern ice wedges. Also a direct dating of microinnclusions of organics material from ice wedges by the AMS method in the Mamontova Gora was performed. New radiocarbon dates of organic matter from sediments surrounding and overlying of ice wedges has been obtained. Using the known ratios of mean winter and mean January temperatures with isotopic composition of ice wedges, the winter palaeotemperatures of Central Yakutia were reconstructed for key periods of the Late Pleistocene. The main conclusions of the study are: a) the mean winter air temperature during the majority of the period of formation of the Late Pleistocene ice wedges of the Mamontova Gora was in the range from -28 to -31 °C, the average January temperatures reached -42, -46 °C; b) in the Syrdach Lake region the winter conditions were slightly more severe: the mean winter temperature varied mainly from -30 to -32 ° C, the average January temperatures reached -44, -48 °C; c) in the Holocene, the average winter temperatures were higher: from -24 to -28 °C, and the mean January temperatures from -36 to -42 °C.

Keywords: Syrdakh, Mamontova Gora, AMS-dating, radiocarbon age, deuterium excess, hydrogen isotope, oxygen isotope, ice wedge, Late Pleistocene, the Holocene

Abstract: The research objects are permafrost sediments and frost mounds in the Sentsa river valley. The problem of their formation in the alluvium period attracts the attention of many scholars in different fields of study (from geo-botanists to specialists in geo-cryology). The complex pilot studies included boreholes drilling, detailed documentation of frost borehole samples, penetrated sections of frost mounds, and river terrace cusps, tacheometric survey of the Sentsa river valley, GPS-anchoring of reference sections and boreholes, defining the ice content (humidity), and the lithological, grain-size and microaggregate composition of lacustrine-alluvial sediments. The analysis has been performed by the specialists of the shared knowledge center “Geodynamics and geochronology” (the Institute of the Earth’s Crust of the Siberian Branch of the Russian Academy of Sciences, Irkutsk) using the modern methods. The authors conclude that frost mounds consist mainly of silt loams with the interlayers of heavy clay sand and ice lenses (up to 0,65 m). Cryo-textures are fissile, crossbedded, thick-schlier, wide-meshed, basal. The designed 3D model of the relief speaks for the presence of either a vast area with many frost mounds of different sizes, or of one gigantic mound, which at the present time is defragmented due to active thermokarst on a terrace above the flood-plain and thermoerosion of the sides of the Sentsa river. According to the preliminary data, frost mounds are cryogenic formations of a mixed segregation-intrusive genesis. The final goal of the research is the elaboration of a scenario of formation of permafrost lacustrine-alluvial sediments and the creation of a theoretic model of the Holocene evolution of frost mounds of the Oka plateau. 

Keywords: 3D-model of relief, ice content, grain-size composition, cryogenic structures, lithology, permafrost lacustrine-alluvial sediments, frost mounds, ice lenses, segregation-intrusive ice formation, Oka plateau