Строение верхней части криолитозоны и рельеф северо-востока Западной Сибири обусловлены изменением природной обстановки в позднем неоплейстоцене и голоцене. В 2016–2021 гг. изучены разрезы отложений на разных элементах рельефа III озерно-аллювиальной равнины Пур-Тазовского междуречья – увалах и термокарстово-эрозионных ложбинах. В строении верхней части равнины выделены каргинско-сартанские аллювиальные, озерные, склоновые отложения и голоценовые торфяники. На основе стратиграфии и новых геохронологических данных на Пур-Тазовском междуречье выявлены последствия активизации неотектонических процессов в сартанский период и влияния климатических факторов на дифференциацию аккумулятивных и денудационных процессов в голоцене. The structure of the upper part of permafrost and the topographic features in the northeast of Western Siberia were shaped by changes in the natural environment in the Late Pleistocene and Holocene. In 2016–2021, sections of different landforms – ridges and thermokarst-erosional hollows – were studied within the third lacustrine-alluvial plain of the Pur–Taz interfluve. The upper part of the plain includes the Kargin–Sartan alluvial, lacustrine, and slope sediments and Holocene peatlands. Based on the stratigraphy and new geochronological data on the Pur–Taz interfluve, the consequences of the activation of neotectonic processes in the Sartan period and the influence of climatic factors on the differentiation of accumulative and denudation processes in the Holocene were identified.

В 2020 году на территории музейного комплекса Обдорский острога в Салехарде был выполнен комплекс инженерно-геокриологических и геофизических исследований с целью изучения геокриологических условий и пространственной локализации мерзлотника, расположенного в его пределах. В результате исследований показано, что в остроге кровля многолетнемерзлых пород расположена на глубине 4-6м. Уточнено плановое положение мерзлотника, определена его глубина. По результатам исследований установлена мощность сезонно-мерзлого слоя на момент проведения работ и выявлены особенности напряжено-деформированного состояния грунтового массива на территории острога и прилегающем склоне.

The upper part of the subsurface component of the Earth’s cryosphere—polygonal peatlands—are considered in this paper. The polygonal peatlands are widespread in the cryolithozone in northwestern Siberia. When the upper permafrost layer thaws under the influence of climatic fluctuations, the ice-bearing transition and intermediate layers in the polygonal peatlands serve as a buffer zone. Therefore, the identification of these layers is a crucial task. The specific features of the layers, their relationship with ice of various origins, and the properties of peat have been determined. The differences in the structure of the intermediate layer, associated with polygonal microrelief of the surface, have been revealed. Thawing of the transitional layer against the background of modern warming has been recorded on the basis of monitoring of a seasonally thawed layer. To identify the transitional and intermediate layers, the indicators—the cryogenic structure, degree of preservation, color, water content, and density of peat—have been determined.

В 2021 г. продолжен мониторинг глубины сезонного протаивания, температуры многолетнемерзлых пород, активности криогенных процессов, связанных с вытаиванием подземных льдов, и изменений, происходящих с полигональными торфяниками на полуострове Ямал, севере Пур-Тазовского междуречья и Гыданского полуострова. Представлены основные результаты исследований.

Morphology of the ice bodies, their structure and relation between them, age and deformations of host strata were studied in the key geocryological area of Western Yamal (Cape Marre-Sale). A comprehensive monitoring of the section was conducted in the slope, which retreat annually. Wedge, wedge-shaped, fissure ices, upper and bottom massive ice body were allocated by morphology among the cryogenic structures. The upper injective-segregation massive ice is characterized by fragmented preservation, variety of forms and sizes and deforms Upper-Neopleistocene - Holocene sediments with syngenetic polygon wedge ice.

Late Pleistocene and Holocene polygonal-wedge ice is studied in the lower course of the Yenisei River. Ice distribution, features of the formation, chemical and microbiological composition were determined. It was established that ice wedges were formed on the slopes of the depression, in coastal-marine lagoons and in thermokarst during Holocene. The evidence of thermoabrasion and thermokarst in sediments as well as the marine signal in composition of polygonal-wedge ice allowed clarifying the southern limit of the Holocene transgression.

Complex structure of the section across the cape Marre-Sale as well as different approaches to its study are the main reasons for continuation of discussion about the age and genesis of deposits and ground ice. New radiocarbon data complement the previously published information about the age characteristics of upper part of the section. It has been found that the upper strata ices having complex shape occur in layers of different age, while they were formed in the Holocene second half.

Late Pleistocene and Holocene polygonal-wedge ice is studied in the lower course of the Yenisei River. Ice distribution, features of the formation, chemical and microbiological composition were determined. It was established that ice wedges were formed on the slopes of the depression, in coastal-marine lagoons and in thermokarst during Holocene. The evidence of thermoabrasion and thermokarst in sediments as well as the marine signal in composition of polygonal-wedge ice allowed clarifying the southern limit of the Holocene transgression.