pdf № 375, March New

DOI: 10.19110/geov.2026.3.1

Current petroleum exploration is characterized by a high degree of maturity in traditional plays and an increasing need to identify new, complex hydrocarbon traps. One of the most relevant research directions is the detailed structural analysis of the Kama-Kinel Trough System (KKTS) margins. This study focuses on the Tournaisian carbonate clinoform complex within the Aktanysh-Chishmy Trough (Republic of Bashkortostan).

An extensive dataset, including well and seismic data, formed the basis for a detailed seismo-geological analysis. A structural-sedimentary model of the Tournaisian clinoform complex was developed. Five genetic types of exploration targets were identified, including carbonate debris fans, undaform (shelf) units and associated drape structures. Diagnostic features for each type were substantiated, and recommendations for further seismic-based studies were provided.

The application of the approaches described in this paper will improve the reliability of geological modeling and the accuracy of hydrocarbon potential forecasting for carbonate clinoforms, not only within the Republic of Bashkortostan but also across adjacent areas of the Volga-Ural petroleum province. The clinoform complexes of the Kama-Kinel Trough System (KKTS) retain significant potential for further detailed exploration.

Keywords: Aktanish-Chishmy trough, carbonate clinoforms, sedimentary aprons, exploration sites, oil prospects, geological exploration

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DOI: 10.19110/geov.2026.3.2

Detrital chrome spinels in terrigenous rocks of the Alkesvozh suite interact with the rock matrix during metamorphism under greenschist facies conditions. This results in the replacement of chrome spinels by Cr-bearing muscovite (fuchsite) or magnetite. The relict portion of the chrome spinels, as a result of component exchange with the environment, is replaced by secondary chrome spinels, which lack Mg but contain significant Zn contents. The composition of all chrome spinel grains is secondary, but the process of change caused by metamorphism of sedimentary rocks is clearly visible only in some of them. The ZnO content of detrital chrome spinels varies both from grain to grain and within a single grain. The minimum ZnO content recorded by us in chrome spinels is 1.3 wt. %, and the maximum is 17.5 wt. %. The final result of the transformation of chrome spinels is the conservation of their relics in magnetite crystals, or their complete disappearance. The former presence of detrital chrome spinelides in the rock is evidenced only by the presence of Cr in metamorphic minerals (mica, chlorite, and hematite), as well as the synthesis of idiomorphic crystals of Zn-containing (14.4–18.1 wt. % ZnO) chromium spinelide in a fuchsite matrix.

Keywords: detrital chrome spinelide, Zn-containing chrome spinelide, Cr-containing muscovite (fuchsite), metamorphism

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DOI: 10.19110/geov.2026.3.3

For the first time, the content of a wide range of trace elements, including indium, was determined for biotite from trachytoid granites of the Gubanov intrusion and host ovoid granites using the high-precision local SIMS method. It was established that indium in the biotite from granites of the Wiborg rapakivi massif was of magmatic nature and its accumulation was controlled by fractional crystallization. Indium behaved as a typical incompatible element, concentrating in the residual melt. The main elements associated with In during the magmatic stage were Sn, Sc, Sm, Nb, Rb, and Zn. These elements formed a reliable association, confirmed by both parametric and rank correlations. Chlorine likely participated in the transport of In in the form of chloride complexes, but this bond was not stable in mineral phases (biotite). The physicochemical conditions of indium accumulation — reducing conditions and moderately high pressure — favored the incorporation of In³⁺ into biotite, which began to crystallize from the melt under these parameters. The high In content (up to 5.8 ppm) in biotite, combined with the high Sn content (>100 ppm) and a positive correlation with Zn, indicated that the Wiborg massif could be considered potentially promising for In-Sn-Zn mineralization.

Keywords: biotite, indium, rapakivi granites, Wiborg massif, Gubanov intrusion, trace elements, critical metals

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DOI: 10.19110/geov.2026.3.4

The kinetic features of monodisperse spherical silica particle formation are investigated by dynamic light scattering in a model system based on the hydrolysis of tetraethoxysilane in an organic medium.

The analysis of the experimental data reveals three distinct stages of silica particle formation: I) condensation of hydroxysilanes yielding di- and trimers; II) formation of branched polymeric structures; III) spatial packing of the resulting structures into final silica spheres (globules). It is demonstrated that the minimum hydrodynamic radius of silica particles detected during nucleation is independent of the synthesis conditions and is approximately 8 nm.

The established patterns of existence of the stages of formation of spherical silica particles and the associated possibility of controlling their duration will in the future make it possible to program the size and degree of monodispersity of spheres, optimize the methods of introducing the necessary elements into the structure of particles, and improve the technologies for creating nanocomposite materials based on them.

Keywords: monodisperse spherical silica particles, dynamic light scattering, formation mechanism, kinetic features

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