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Climatic and environmental change is leading to increased frequency and intensity of permafrost degradation processes; however, our knowledge of their mechanisms and rate is still limited. We examined structure of deposits, surface topography, and weather conditions during the initiation of a thermo‐erosion gully in eastern Siberia and monitored its changes between 2020 and 2022. The initiation of the gully was caused by a combination of processes: (1) the catchment area of the gully was artificially increased several decades ago as a result of the interception of runoff by the winter road; (2) ice‐wedge degradation led to surface runoff concentration above the gully head, while a large volume of ground ice remained in other parts of the slope, and frost cracking continued; (3) the entry of water into frost cracks formed underground tunnels; and (4) high air temperatures and heavy rainfall immediately before the gully appearance resulted in the expansion of the tunnels and collapse of their roof. In 2 years, the volume of the gully reached 1000 m3; at least 40% of that volume consists of ground ice. The gully development did not significantly change the water chemistry due to significant water freshening caused by melting of ground ice. [ABSTRACT FROM AUTHOR]

The content of phenolic compounds (flavonols, flavans (catechins), tannins), polysaccharides (pectins, protopectins), and tetraterpenes (carotenoids), as well as the antioxidant activity of Cichorium intybus L., Taraxacum officinale Wigg., Arnica iljinii (Maguire) Iljin., and Echinops sphaerocephalus L. cultivated in conditions of Western Siberia were studied. A significant part of the biologically active substances is represented by tannins (up 28.25%) and protopectins (up 11.11%). The content of flavonoids in the studied samples of C. intybus plants agree with the values of this indicator for the chicory herb from other regions of the Russian Federation, including its commercial growing regions. The inflorescences and leaves of the studied samples of T. officinale are characterized by approximately identical contents of flavonols (1.02–1.43%), pectins (0.80–1.08%), and protopectins (7.94–8.87%). The leaves and inflorescences of A. iljinii are distinguished by fairly high contents of flavonols (up to 4.23%) and tannins (up to 28.25%). The leaves of E. sphaerocephalus are significantly superior to the inflorescences in terms of the content of tannins (8.34%), catechins (36.3 mg%), protopectins (10.06%), and carotenoids (64.60 mg%); flavonols are present in equal proportions in the leaves (0.68%) and inflorescences (0.64%). The indicators of the total content of phenolic antioxidants in the leaves and inflorescences of C. intybus, T. officinale, A. iljinii, and E. sphaerocephalus do not differ significantly. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate subaerial taliks' geology, configuration, ground temperature and groundwater level in the continuous permafrost environment of Central Yakutia (Eastern Siberia). The study included geophysical surveys, borehole drilling and measurements of ground temperature and groundwater level variation in a talik aquifer in the Shestakovka research watershed. The talik occupies a gentle, sandy slope covered by a sparse pine forest. Its thickness varies from 3 to 17 m. The talik has several water-conducting branches along its slope. The seasonal thaw layer outside the talik and the talik itself form a single aquifer at the end of the summer. Water-saturated deposits in the talik have a temperature of about 0 °C throughout the year and do not freeze because of the constant filtration of water through the pores and convective heat transfer. Although the groundwater level is relatively close to the land surface, at a depth of just 1–3 m, it has very weak response to snowmelt and precipitation events. The maximum groundwater level occurs in February under cryogenic pressure due to deep seasonal ground freezing above the talik aquifer. Complicated relations between the landscape and the groundwater in the given geological conditions lead to the long-term existence of talik aquifers in the continuous permafrost environment. [ABSTRACT FROM AUTHOR]

Mesoproterozoic period included several global tectonic events like break-up of Nuna and formation of Rodinia. However, although Siberia is a significant piece of both supercontinents, Mesoproterozoic time is marked by quiescence of magmatic and tectonic activity in it. We report here a mafic dyke (named Gornostakh dyke) in the southeastern Siberian Craton dated at 1419 ± 32 Ma by LA-ICPMS U–Pb geochronology of apatite. The dyke has tholeiitic compositions with high MgO and alkaline content, low-Ti, and arc-like trace element pattern. Due to the absence of subduction tectonics in the study area, geochemical data could be attributed to a significant contribution from metasomatically enriched subcontinental lithospheric mantle previously modified by subduction processes. That kind of composition is common for low-Ti dykes of intraplate flood basalt provinces similar to, for example, Permian–Triassic Siberian large igneous province (LIP). Paleogeographic reconstructions suggest that Siberia was connected to Laurentia and Baltica and their reconfiguration interrupts a prolonged tectonic quiescence in the Siberian Craton from ca. 1.88 Ga reflecting a transition from Nuna to Rodinia configuration. The mafic magmatism on 1419 Ma on the southeastern margin of the Siberian Craton together with coeval extensional tectonics observed in the structure of the Sette-Daban ridge proposes a hypothetical LIP which may be a direct consequence of the beginning of this transition. [ABSTRACT FROM AUTHOR]

The results of palynological and micropaleontological studies of the Upper Cretaceous–Cenozoic strata penetrated by Boreholes 23 and 19 of the Aleiskaya area (Altai krai) are presented. The obtained data allowed us to substantiate the age of the deposits, make suggestions concerning their depositional environment, and to clarify the subdivision of geological section into formations. Two palynological assemblages were recognized in the Cretaceous part of the Borehole 23 section: the first one characterizes the Len'ki Formation and is dated as Cenomanian–Turonian; the second one is recognized in the Upper Sym Subformation and is dated as Maastrichtian. The Upper Cretaceous sequence is overlain by the terrestrial Ostrovnoe Formation (Paleogene). In Boreholes 19 and 23, this formation contains presumably Late Paleocene–Early Eocene and Middle Eocene spore and pollen spectra, respectively. Palynological data substantiate the Late Miocene age of sedimentary strata in the upper part of the geological section of Borehole 23 and their belonging to the Pavlodar Formation. The structure of the palynological assemblages, the specific features of the macerate, and the absence of foraminifers indicate the continental genesis of the Upper Cretaceous–Paleogene sedimentary deposits in the southern part of the Kulunda Depression in Altai krai. [ABSTRACT FROM AUTHOR]

Mesozoic sections in the New Siberian Archipelago are important for understanding of the geology of underexplored shelf areas in the east of the Laptev Sea and in the west of the East Siberian Sea. They are reference sections for interpretation of seismic data in these regions. However, there are still many unresolved problems concerning the lithology, lateral extent, and age of Mesozoic deposits, as the sections have a complex structure and are heavily deformed. The performed research makes a basis for the first facies zoning of Jurassic and Cretaceous deposits in the New Siberian Islands and adjacent landmasses of continental Siberia at the junction of the Laptev and East Siberian Seas. The lithostratigraphic division of the Jurassic and Cretaceous is refined, being proposed for the first time for some stratigraphic intervals, and allows updating their lithostratigraphic division (or undertaking it for the first time for some stratigraphic intervals). Facies features of Jurassic and Cretaceous deposits allow the definition of three depositional series. [ABSTRACT FROM AUTHOR]

This work presents results of complex research (palynological, macro- and microfaunistic, and paleomagnetic) of Upper Cretaceous deposits, opened by borehole no. 8 in the Russkaya Polyana District (the southern margin of the Omsk Depression, Southwestern Siberia). The paleontological data obtained allowed us to establish the age of deposits. Based on dinocysts, nannoplankton and spore-pollen complexes, the section of borehole no. 8 has been divided into Pokur, Kuznetsovo, Ipatovo, Slavgorod, and Gan'kino Formations. This work gives data on the composition of zonal palynomorphs, nannoplankton, and microfaunistic complexes. Based on the complex data obtained, the magnetostratigraphic section of Upper Cretaceous deposits has been developed. The section consists of three magnetozones: normal and two reversed polarity magnetozones. The Pokur, Kuznetsovo and Ipatovo Formation (Cenomanian-Santonian) belong to the long normal polarity magnetozone; the Slavgorod and Gan'kino Formations (Campanian-Maastrichtian), separated by a stratigraphic break, belong to reversed polarity magnetozones. The magnetostratigraphic section has been correlated with the general magnetostratigraphic and magnetochronological time scales. [ABSTRACT FROM AUTHOR]

Abstract: The Oxfordian–Lower Hauterivian section of the Nordvik Peninsula (northern Central Siberia) is a reference for developing zonal scales for various fossil groups and improving the Boreal zonal standard. In the middle 1950s–late 1980s, it was studied extensively by geologists, stratigraphers, lithologists, and experts on various fossil groups. These studies yielded rich fossil and microfossil collections and a set of parallel zonal scales for various faunal groups. Recently, a new detailed ammonite zonation of the Oxfordian and Kimmeridgian units of this section has been proposed. These results contradict the previous biostratigraphic data on ammonites, foraminifers, and palynomorphs. In the present paper, all the biostratigraphic data on the Oxfordian and Kimmeridgian units of the Nordvik Peninsula (Cape Urdyuk-Khaya) and northern Central Siberia undergo a comprehensive analysis and comparison with those on the Boreal Realm. The ammonite-constrained stratigraphic position of the lower Upper Jurassic in the Cape Urdyuk-Khaya section is interpreted as Upper Oxfordian or Middle Oxfordian. In our view, this difference in the understanding is due to the misidentification of some Oxfordian ammonite forms. The zones based on other fossil groups (foraminifers, dinocysts) which were distinguished in the Upper Oxfordian and Kimmeridgian sections of the Nordvik Peninsula are well traceable circumarctically. Their stratigraphic position in various regions of the Northern Hemisphere is constrained by ammonites and bivalves. However, if we use the last alternative ammonite zonation of this section part, hardly explicable contradictions will appear in interregional foraminiferal and dinocyst correlations. [Copyright &y& Elsevier]

The flow of large northern rivers has increased, but regional patterns of changes are not well understood. The aim of this study is the estimation of monthly discharge changes of the 11 river catchments in the Aldan River basin in Eastern Siberia, the largest Lena River tributary and the sixth largest river in Russia. We considered the trend dependence on month, number of years in the sample, finish and start years, and basin area. The median fraction of samples with no trend, positive and negative trends are 70.5%, 28.5%, and 1%, respectively. Longer samples tend to show more positive trends than shorter ones. There is an increasing fraction of samples with positive trends as a function of later sample end year, whereas the start year does not result in a similar pattern. The larger basins, with one exception, have more positive trends than smaller ones. The trends in monthly streamflow have prominent seasonality with absence of positive trends in June and increasing fraction of samples with positive trends from October till April. The study reports the recent streamflow changes on the rarely analyzed rivers in Eastern Siberia, where air temperature rises faster than in average on the globe. The study results are important for water resources management in the region and better understanding of current environmental changes. [ABSTRACT FROM AUTHOR]

Rich assemblages of phytoplankton and microforaminifera (foraminifera linings) are found in the marine Lower Cretaceous section from the Yatria River (Subarctic Ural). The Lower Cretaceous (Upper Volgian to Lower Hauterivian) dinocyst and microforaminifera biostratigraphy is calibrated against the ammonite zones. The dinocyst stratigraphy differs from Arctic Canada zonation, except for the Berriasian Paragonyaulacysta? borealis zone, and shows significant similarity with the zonal subdivision of Boreal regions of Europe. The distribution of phytoplankton and microforaminifera is related to relative sea level variations. Consecutive changes of phytoplankton associations (2 in the Berriasian, 3 in the Valanginian-Early Hauterivian, 4 in the Early Hauterivian), lateral zonations of microforaminifera (2 in the Berriasian, 2 in the Valanginian) and their relation to environmental changes in the Lower Cretaceous seas of the Subarctic Ural Basin are established. [ABSTRACT FROM PUBLISHER]

Vertisols and vertic soils are known in a wide range of bioclimatic environments. The aim of this research was to identify possible vertic features in ultra-continental climate with gelic soil temperature regime with MAAT < 1 °C. Detailed morphological investigation supported by micromorphological and physical attributes identified vertic features both at the order and subgroup levels in Buryatia (Trans-Baikal region), where soils are formed under MAAT − 4.2 °C, and are underlain by permafrost. Vertisol was found in the shoulder position, while the soils of the summit and the backslope position were classified as vertic intergrades of Phaeozem. Vertisol has cracks on the surface, slickensides and wedge-shaped aggregates within the profile, 47–55% of clay, extremely high smectite contents (up to 98% of clay fraction). Vertic Phaeozems on the summit and backslope positions have similar morphological attributes but at the initial stage of formation, and without the formation of vertic horizon. Both Vertisol and Vertic Phaeozems have vertic features at microlevel such as a variety of striated b-fabrics, an open porphyric c/f-related distribution, planar voids, a blocky microstructure, wedge-shaped microaggregates. These soils have been formed under the joint impact of deep winter freezing, permafrost formation, and shrink-swell processes, and show the combination of primary cryogenic features and cryogenic features transformed by the shrink-swell and shearing processes. We found that Vertisols can form not only in cold environments, but also in ultra-continental cold environments with permafrost and negative mean annual air temperatures. However, their areas in Buryatia are limited in size to the warmest and driest positions in the landscape, namely south facing slopes. The discovery of Vertisols in ultra-continental climates will be a challenge for current soil classification systems, like Soil Taxonomy, which will need a provisional taxonomic category to accommodate such soils under gelic temperature regimes. We propose to introduce Gelert suborder and Vertic subgroup to Haplogeloll great group. [ABSTRACT FROM AUTHOR]