Home – Home – Jornals – Russian Geology and Geophysics 2026 number 9

This paper provides a detailed characterization of karite, which is represented by diamond-bearing fossils from the Kara astrobleme that formed from organic matter, specifically from fragments of ungelified wood. A comprehensive range of methods was used for this analysis, including the study of structural features at the atomic resolution level, material composition, and spectroscopic characteristics. The diagnostic features of these fossils are examined, and the mechanisms of their formation and ontogeny are analyzed. A detailed study of the ontogenetic specificity of the diamond fossils, combined with data on their structural and material characteristics, revealed fundamental differences between the mechanisms of their formation and those of typical paramorphs and pseudomorphs. Consequently, these diamond fossils are classified as pseudo-paramorphs. Given the specific conditions required for the formation of the described diamond aggregates and other carbon phases derived from organic remains by impact, it is proposed that a new variety of fossils be distinguished: impact fossils. Finally, the potential use of impact diamond fossils for geological and genetic reconstructions is assessed.

We studied the chemical and isotope (C and O) composition of carbonate deposits and the age distribution of detrital zircon grains from the late Precambrian deposits of the Mana trough at the Sayan segment of the Central Asian Mobile Belt (CAMB). Limestones of the volcanosedimentary Kuvai Group (Mana and Bakhta formations) of oceanic genesis display high positive δ¹³C values, up to +8.9‰, which, along with other data, constrain their age to the Late Riphean (оr the late Tonian). The Angaloi Horizon strata have near-zero or slightly positive δ¹³C values, and the minimum detrital-zircon age is ca. 580 Ma, i.e., they can be assigned to the Late Vendian (or the late Ediacaran). In the upper part of the Anastas’ino Horizon, two pronounced positive δ¹³C excursions contrasting to near-zero values have been established; they mark the base of the Tommotian Stage (Cambrian). The age spectra of detrital zircons from the Angaloi Horizon and the lower bed of the Anastas’ino Horizon demonstrate two Neoproterozoic populations with peaks at 710 and 630 Ma. Zircons of these ages might have formed in volcanic and granitoid complexes at the Sayan segment of the CAMB. The presence of Paleoproterozoic zircon grains in the studied deposits suggests that the accretion of the sedimentary basin of the Mana trough to the Siberian Craton was completed in the early Cambrian. These conclusions are supported by geochemical indicators of the depositional environments of carbonates and by geodynamic reconstructions for the adjacent areas.

This article examines the structure, composition, and textural features of the Griva Sequence in the Volchya Griva section and the paragenetically associated relief. Additional data supporting the aeolian origin of the Griva Sequence and the Griva relief are presented. Optically stimulated luminescence and infrared stimulated luminescence dating of the Volchya Griva section indicate that the Griva Sequence formed during the last glaciation and fully corresponds to Marine Isotope Stage (MIS) 2. The findings confirm that aeolian relief formation and the intensification of aeolian processes occurred during cold glacial periods of the Late Pleistocene, when southwesterly winds prevailed. The textural and structural characteristics of the Griva Sequence are similar to those of Upper Pleistocene niveo-aeolian sands that formed in cold, periglacial, arid regions of the world and are distributed along the southern margin of the last glacial ice sheets from Northwestern Europe to Western Siberia and Alaska. The formation of a deflationary truncation and a system of mega-yardangs in the northern part of the Lake Chany basin indicates a significant intensification of aeolian processes at the transition between the deposition of the lower and upper members of the Griva Sequence. The orientation of the Griva relief, which coincides with the prevailing direction of modern winds, suggests that wind directions during the cold and warm epochs of the Quaternary in southern Western Siberia were similar. The complete stratigraphy of the Volchya Griva section, its correspondence to the last glaciation and MIS 2, the presence of the largest Eurasian mammoth faunal locality, its distinct lithological characteristics, and the relatively high degree of its study allow this section to be considered one of the reference sections for the Upper Pleistocene of Siberia. It should be regarded as the stratotype of the widely distributed Griva Sequence in this area, which is proposed as a separate Baraba horizon (formation) for the south of Western Siberia, comprising the Eltsovka and Bagan loesses and the Suma soil that separates them.

Climate has a profound effect on human life and plays a significant role in its history. There are numerous examples of serious social upheavals of local and regional proportions over the last few millennia associated with climate change. Therefore, current global warming and its causes are one of the most pressing and controversial issues in both the scientific and public communities. In this paper, we have assessed the possible contribution of the anthropogenic factor in the formation of climate in different regions of the world during the industrial period (since 1850) by analyzing data on past conditions of the climate system over a sufficiently long time interval. Using harmonic analysis, we have constructed empirical models of climate change over time for these regions and, by extrapolating them to the industrial period, have obtained “natural” scenarios of temperature variations that take into account only the impact of the natural environment and exclude the anthropogenic factor. In all studied regions, instrumentally recorded temperature values significantly exceed the “model” ones. On average, according to “natural” scenarios, the global air temperature should have increased by ~0.02 °C during the industrial period; however, it actually increased by ~0.94 °C. The deviation has been evident since around 1920, gradually increasing subsequently. These facts may indicate the manifestation of an anthropogenic factor that makes a certain contribution to current global warming.

We present the results of numerical modeling and inversion of lateral logging sounding (LLS, or BKZ in Russian) data to determine the geoelectric parameters for oil-and-gas-bearing reservoirs of the northern fields in Western Siberia. The research provides the analysis of synthetic LLS signals calculated for a typical model of the Achimovo Formation of the Yamburg field, which is characterized by small reservoir thickness. We have considered the influence of changes in parameters such as the formation resistivity, the thickness of the invasion zone, and the depth shift on the LLS signals. We have assessed the accuracy of reservoir parameter reconstruction using 2D numerical inversion, have determined areas of equivalence, and have proposed recommendations for minimizing errors. The results show that the greatest sensitivity of LLS signals corresponds to changes in the resistivity of a formation and the thickness of the invasion zone, with the error in determining the formation resistivity being up to 12%.

This paper presents the development and experimental validation of an active thermometry method for quantitatively assessing the fluid flow rate in horizontal wells. Two approaches are investigated in experiments on a physical well model under single-phase flow conditions: the calorimetric method, based on the integral superheat of a homogenized flow, and the convective method, which relies on the relationship between the heated pipe wall temperature and the flow rate. The Richardson number (Ri) is identified as the key criterion governing the heat transfer mechanism. For Ri > 1 (low flow rate), thermogravitational effects dominate, leading to significant thermal stratification of the flow. Under such conditions, the calorimetric method proves more reliable and enables flow rate determination with high accuracy (a deviation of ≤ 10%). The limitations of the convective method are also identified. In this study, the interpretation of the convective method considers only the forced convection component (Dittus-Boelter model). This method is valid only for Ri < 0.1 (high flow rates). This work provides a methodological foundation for further development of the method, with key directions including the refinement of the convective model to account for free (natural) convection and the adaptation of both approaches to multiphase flow conditions.

This study analyzes the amplitude-frequency characteristics (AFC) of deep ground penetrating radar (GPR) data gathered using variable offsets within the permafrost of the Nadym District, Yamalo-Nenets Autonomous Okrug. The initial frequency response of the raw data, which underwent only basic pre-processing, is presented, evaluating the effects of transmitter-receiver separation (100-750 m) as well as the spatial and depth-based placement of the analysis zone. This approach reveals the spectral evolution of electromagnetic signals within the geological environment during the late stages of the process. Results indicate that as the distance from the source increases, the signal undergoes standard attenuation, alongside three primary spectral effects: a downward frequency shift of the peak amplitude, a narrowing of the spectral bandwidth, and a significant rise in low-frequency components, the latter being primarily attributed to zero-line drift. Adopting spectral analysis techniques from seismic exploration for deep GPR data is a promising way to refine data processing and improve subsurface interpretation.

This article discusses the development of a methodology for creating a semi-synthetic dataset to train a neural network for the detection and segmentation of hyperbolic diffractions in ground-penetrating radar (GPR) data. The proposed method offers a solution by generating annotated data where target synthetic objects are placed onto real background sections that are confirmed to be free of the target objects. This approach enables model fine-tuning without direct manual labeling for any specific survey type. The final algorithm was successfully validated on GPR data from the Austre Grønfjordbreen glacier. This solution will significantly simplify the analysis of the internal structure of polythermal glaciers and allow us to assess their hydrothermal structure.

Spectral decomposition is a widely used method of qualitative seismic interpretation, a key limitation of which lies in the subjective selection of frequency components for visualization. Existing approaches based on the analysis of the global Fourier amplitude spectrum do not account for the temporal localization of the signal’s spectral content. We introduce a new method for automatic frequency selection based on approximating local spectra obtained via the short-time Fourier transform (STFT) as a linear combination of three Morlet wavelet spectra. This approach enables the extraction of time-dependent frequency trajectories that capture the evolution of the signal’s spectral content, rather than relying on a fixed frequency triplet over the entire interval. We have solved the optimization problem using the differential evolution algorithm and have tested the method on field data from the West Siberian oil-and-gas province. Quantitative evaluation using Shannon and Rényi entropy metrics, as well as a colorfulness metric, has shown increased visual separability and color contrast in RGB composites. The proposed method reduces the subjectivity of interpretation and ensures reproducible results.

The results of magnetic survey investigations conducted in the floodplain areas of the Yellow and Black rivers in the Lori Region of Armenia (northern part of the Republic of Armenia) are presented. Based on field observations, digital and graphical maps of the anomalous magnetic field (∆T_a) and its three-dimensional model were constructed. Analysis of the anomalous magnetic field structure made it possible to identify a number of positive and negative anomalous zones associated with geological formations differing in magnetic properties. It has been shown that the positive anomalies are caused by the presence of ultrabasic rocks (peridotites, pyroxenites) exposed along the left bank of the Yellow River and the right bank of the Black River. An extensive negative anomaly zone has been identified and interpreted as a reflection of a tectonic fault zone and the adjacent thick area of hydrothermally altered rocks. Comparison with the data on the physical properties of rocks confirmed the high contrast of magnetic characteristics between the ultrabasic and ore-hosting rocks.