pdf № 379, July

DOI: 10.19110/geov.2026.7.1

Ключевые слова: Тимано-Североуральский регион, Приполярный Урал, верхнедокембрийские отложения, стратиграфия, корреляция, циркон, U-Pb-возраст

The northern Lyapin anticlinorium of the Subpolar Urals exposes the most complete Precambrian section of the entire Timan-Northern Ural region. Therefore, updating the subdivision schemes of these formations is important not only for the Northern Urals but also for the Kanin- Timan Ridge, most of which lacks (or is not exposed by erosion) Pre-Upper Riphean deposits. Over the past 10–15 years, U-Pb (LA-ICP-MS) dating of detrital zircon grains from metaterrigenous deposits of the Upper Precambrian part of the Subpolar Ural section has established their age relationships. Based on new geochronological data, both obtained with the author's participation and borrowed from literary sources, the stratigraphic scheme of Precambrian formations in this region has been refined, a comparative analysis of available factual data on the age of Late Precambrian strata in adjacent areas of the Timan- Northern Ural region has been conducted, and age correlations have been identified. It has been shown that in the Subpolar and Polar Urals, the lower age limit of Upper Precambrian strata is no older than 750 million years. In the rest of the Timan-Northern Ural region, accumulation of Upper Precambrian sediments also began in the Late Riphean, apparently no earlier than 800 million years ago.

The comparability of age spectra of detrital zircon grains from the late Precambrian terrigenous (and metaterrigenous) deposits of the Lyapin anticlinorium of the Subpolar Urals, the Kvarkush-Kamennogorsk anticlinorium of the Northern Urals, and most areas of the Kanin-Timan Ridge suggests that they all formed in the same sedimentary basin from the same provenances. The absence of Lower-Middle Riphean deposits in the Late Precambrian section of the Kanin-Timan Ridge and the Northern Urals can be explained by the highstand of this area before the Late Riphean and its location within the inner part of the Nuna/Columbia supercontinent fragment, which escaped destruction until the incorporation of Proto-Baltica into Rodinia.

Keywords: Timan-Northern Ural region, Subpolar Urals, Upper Precambrian deposits, stratigraphy, correlation, zircon, U-Pb age

Download full text

DOI: 10.19110/geov.2026.7.2

In the upper reaches of the Uls River, on its right tributary, the Myka River, rocks of the Middle and Upper Ordovician Chuval Formation were exposed by artificial outcrop. Talc shales, previously unknown in the Chuval Formation, containing anomalously high Ni concentrations (up to 3320 g/t), were described for the first time here. The stratigraphic interval, approximately 15 m thick, consisted of alternating interbeds of talc-bearing schists, quartz sandstones, and volcaniclastic sandstones. To establish the compositional features and genetic affiliation of the rocks that served as a substrate for talc-containing shales, a study of the composition of petrogenic oxides and trace elements, morphological features and composition of a number of minerals was conducted using a scanning electron microscope.

Interpretation of the results of chemical analyses and the characteristics of the REE distribution allowed us to conclude that the talc-containing rocks were of metasomatic origin and had been probably formed as a result of hydrothermal transformations of the volcanogenic-sedimentary rocks of the Chuval Formation containing basic volcaniclastic material.

The abnormally high concentrations of nickel, chromium and cobalt were stratiform in nature, were confined to the volcanogenic-sedimentary part, could have a wide areal distribution and were of interest in the search for larger ore occurrences.

Keywords: shales, Chuval Formation, chemical composition, talc, serpentine, chromite

Download full text

DOI: 10.19110/geov.2026.7.3

Based on structural and chemical studies of the organic matter of Phylladoderma arberi Zalessky compressions, which form the Permian Phylladoderma coal (Pechora coal basin, Komi Republic, Russia), data have been obtained on the existence of compositionally homogeneous H-type protolignin in Permian plant derivatives. Low molecular weight phenolic compounds and structures identified by pyrolytic gas chromatography-mass spectrometry are represented by p-coumaric units (H-lignin). Modern lignins of this composition are unknown. Electron paramagnetic resonance has been used to describe the paramagnetic properties of the organic matter of P. arberi compressions, with a paramagnetic center concentration of approximately 3 × 10¹⁸ spin/g. A comparison of the obtained data with the results of previous studies of the Devonian and Carboniferous plant remains indicates a similar structural type of protolignins. A description of the cuticular structure of P. arberi is given.

Keywords: chemosystematics, Phylladoderma arberi Zalessky compressions, lignin, permian Phylladoderma coal, Pechora coal basin

Download full text

DOI: 10.19110/geov.2026.7.4

Mineralogical investigation of the soil profiles as part of the ecogeological monitoring of the Seregovskoe rock salt deposit territory is carried out. The effect of short-term anthropogenic pollution (salinization) on clay minerals in saline soils is demonstrated. A mineralogical description of soil profiles formed under the influence of natural processes and transformed as a result of environmental salinization in the zone affected by brine extraction at the Seregovskoe rock salt deposit is provided. A comparative analysis of changes in soil composition in the salinized area near borehole 2-PS is conducted based on observations in 2005 and 2022. The study of saline and background areas revealed that soil salinization has a clearly defined local nature and is confined to the brine drainage cone, not extending beyond it. It is shown that swelling of soil layered silicates can change their structure during salinization and form non-swelling mixed-layer phases. A gradual restoration of soil composition over time is noted.

Keywords: clay minerals, soils, salinization of the territory, Seregovskoe salt deposit, X-ray analysis of clays

Download full text

DOI: 10.19110/geov.2026.7.5

The article continues the publication of documents from the personal archive of Professor D. P. Grigoriev, kept at the Russian Mineralogical Society: D. P. Grigoriev's autobiography, clarifying some episodes of his life and work, as well as the reviews of Academician V. A. Obruchev and Corresponding Member (later also Academician) D. S. Belyankin for his doctoral dissertation, defended during the evacuation in Sverdlovsk in 1943. The review by Academician A. E. Fersman has not yet been found. In addition to the previously published materials about him, this article includes a speech by Professor G. L. Gaukins (London Geological Society) at the awarding of the Wollaston Medal to A. E. Fersman and his response delivered by the attaché of the Soviet Embassy in London. The relevance of the article lies in the need to defend the priorities of Russian science. The goal is to provide the most comprehensive coverage of its history based on documents. D. P. Grigoriev's archive, consisting of letters, photographs, and other documents, reflects several decades of pre-war, war, and post-war history of Russian geology, mineralogy, and crystallography. The article is intended for professional historians of science and a wide range of enthusiasts, including members of the Russian Academy of Sciences, university professors, postgraduate students, and undergraduates.

Keywords: D. P. Grigoriev, D. S. Belyankin, V. A. Obruchev, A. E. Fersman, personal archives, history of science, experimental mineralogy, ontogeny of minerals

Download full text