pdf № 356, August

DOI: 10.19110/geov.2024.8.1

Upper Ordovician carbonate deposits in the Northern Urals are the most common in the Ilych River basin. At the same time, the sections drilled here, which are the objects of this study, have a fragmentary character and tectonic boundaries, which led to significantly different ideas about the age of some strata and, as a result, to the ambiguity of their sedimentation conditions. The lithological-facies, paleoecological and paleontological studies revealed that the section of the Upper Ordovician carbonate deposits in the Northern Urals was represented by two formations, the Bolshaya Kosya reef and four thickness covering three tiers of the International Stratigraphic Scale of the Upper Ordovician — Sandbian, Katian and Hirnantian. The analysis of the spatiotemporal relationships of 36 lithotypes isolated in these sediments showed that they were grouped into 10 paragenetic associations of rocks reflecting the change of sedimentation conditions from a deep-water ramp with the accumulation of terrigenous calcareous silts (Sandbian) to a carbonate shelf with a clearly defined brow and the formation of a reef shoal on it (Middle Katian) and further to a shallow ramp with the widespread development of erosion processes and the formation of sandbanks (Late Katian-Нirnantian).

Keywords: carbonates, lithotypes, paragenetic associations, carbonate platform, Upper Ordovician, Northern Urals

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DOI: 10.19110/geov.2024.8.2

The main result of the work was the identification of the present-day seismotectonic regime of an active zone of the Lyakhovichi regional fault. The areal and space-time distribution of the earthquake epicenters along the fault line was reconstructed. The coordinates of the seismically active fault zone located within an area of 52.738—53.037° N and 26.830—28.034° E were determined. It was found that the distribution of earthquakes along the fault line occurred non-uniformly in space and time. The period from 2012 till 2021 was the most active one by the quantity of occurred earth quakes (169) and released total seismic energy (4.5929·10⁹ J). The strongest earthquake with a magnitude M = 2.9 was recorded in the eastern part of the fault on September 03, 2021. Our reconstructions determined the value of seismic dislocation along the fault, which corresponded to the kinematic slip fault. To characterize the modern seismogeodynamic activity in the Lyakhovichi fault zone, a comprehensive technique based on long-term monitoring of seismic events was used. Based on the performed studies, the seismotectonic potential of the seismoactive zone of the Lyakhovichi fault was determined.

Keywords: earthquake, epicentre, magnitude, fault, tectonics, geodynamics, seismotectonic activity

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DOI: 10.19110/geov.2024.8.3

The Belovezhian stage is a part of the Middle Pleistocene of Belarus. It is located between the Narevian and Berezinian glacial stages and consists of three substages: Borkovian, Nizhninian and Mogilevian. Belovezhian stage corresponds to the Muchkapian one in the stratigraphic scheme of the Pleistocene of the European part of Russia, which is also subdivided into the Glazovian, Podrudnyanian and Konakhovian substages and located between the Donian and Okian glacial stages.

Generalization and analysis of the results of accumulated palynological and geological studies indicate that the Borkovian, Nizhninian and Mogilevian substages can be assigned a higher status — stages. Arguments in favor of such a division are presented in this paper. This point of view was repeatedly expressed earlier, but was not accepted in the modern stratigraphic scheme of the Pleistocene of Belarus.

Another topical issue of the stratigraphy of this part of Pleistocene, considered within this article, is the validity of the Korchevian substage within the Narevian glacial stage. According to the available palynological data, the deposits of the Korchevian substage are characterized by a similar sequence and features of pollen zones as the Mogilevian accumulations within the Belovezhian stage, and therefore their age should be determined as Mogilevian.

To substantiate the conclusions, a detailed interregional correlation of the studied deposits with the corresponding deposits of other regions of Europe by pollen zones was carried out and presented in this article.

Keywords: Belarus, Pleistocene, Belovezhian stage, Narevian stage, Korchevian substage, Muchkapian stage, stratigraphy, correlation

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DOI: 10.19110/geov.2024.8.4

The crystal structure of a potentially new member of the eudialyte group, the Nb-deficient analogue of oneillite from Mont Saint-Hilaire, Québec, Canada, with the idealized formula: Na₁₃(Ca₃Mn₃)Zr₃(Fe,Mn)₃(ÿ,Nb)(Si,Nb, ÿ) [Si₃O₉]₂[Si₉O₂₇]₂(O,OH,Cl)₃·2H₂O, has been re-studied within the space group P3. The unit-cell parameters are: a = 14.134(3), c = 30.178(6) Å, V = 52201 ų. The crystal structure of the mineral has been previously investigated using the space group R3 (typical for the members of oneillite family). In this work a structural model characterized by 155 crystallographic sites was solved in the frame of the low symmetry space group P3 and refined to R = 5.9 % using 4179 reflections with F > 2s(F). The cation distribution between the key sites in low symmetry is more detailed.

Keywords: eudialyte group, oneillite, crystal structure, blocky isomorphism, key sites, primitive unit cell, Mont Saint-Hilaire

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DOI: 10.19110/geov.2024.8.5

A short essay about German chemist Wolfgang Ostwald and his book "The World of Neglected Dimensions" provides information about the life and work of the scientist and discusses some results of research breakthrough into the world of neglected dimensions. Attention is drawn to the importance of studying the protomineral world, called "new world of neglected dimensions". Modern instrumental possibilities for the study are noted.

Keywords: W. Ostwald, "world of neglected dimensions", dispersed state of matter, stages of invasion into the nanoworld, protomineral world, femtosecond and attosecond pulses in the study of objects of the protomineral world

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