The authors compared the Neoarchean and Early Paleoproterozoic (Sumian) igneous rock compositions in the Karelian province of the Fennoscandian Shield. The Neoarchean basite-ultrabasite magmatism was not widely spread, but granitoid magmatism was critical for crust formation. At that time, the first subalkaline and alkaline rocks appeared in the Shield: sanukitoids (2.75–2.71 Ga), granites and pegmatites (2.7–2.65 Ga), and carbonatites (2.61 Ga). After a magmatic activity hiatus of about 100 Ma, the Proterozoic began with large-scale ultrabasite-basite magmatism manifested as layered intrusions, drusites, and volcanic complexes (2.5–2.45 Ga). Sumian basites are enriched in light rare earth elements and have negative εNd(t) values ranging from −3.4 to −0.5. The Neoarchean metakomatiites and metabasalts include primitive varieties as well as those enriched in light rare earth elements; they both have positive εNd(t) values ranging from +0.5 to +2.6. The Neoarchean rocks of intermediate-felsic composition present metavolcanites and various granitoids — from tonalite-trondhjemite-granodiorite (TTG) to sanukitoids and plagiomicrocline granites. TTG, sanukitoids, and metavolcanics (2.76– 2.70 Ga) are enriched in K, Ba, Sr, and light rare earth elements, and are characterized by ε_Nd(t) values from –1 to +2.5. Plagiomicrocline granites (2.72–2.65 Ga) vary in rare and rare earth element contents, as well as ε_Nd(t) values from –5 to +2.2. The Sumian intermediate-felsic rocks have two groups. Metavolcanites with SiO₂ <65 %, which have no intrusive analogs, are more likely to be derivatives of the Sumian mafic volcanites. The rocks with SiO₂ >65 % are represented by potassic metarhyolites and granites (2.45–2.40 Ga) with high contents of Ti, Zr, Y, as well as Ba and Rb; they predominantly have negative ε_Nd(t) values from +0.5 to –3.

The paper synthesizes published isotope and geochronological data on ultramafic and mafic complexes in Tuva, including ultramafite, gabbroid, chromitite, basalt volcanite, subvolcanite, and genetically related rocks. The review is based on published U-Pb zircon data (obtained with LA-ICP-MS, SIMS/SHRIMP, and ID-TIMS), as well as ⁴⁰Ar/³⁹Ar and K–Ar ages. Their interpretation adds to analyzing the morphological, microtextural, geochemical, and isotope criteria to discriminate between different genetic zircon types. The available geochronological dataset for Tuva spans the interval from the Precambrian to the Paleogene–Quaternary and defines three principal age groupings: Vendian–Ordovician, Devonian–Permian, and Paleogene–Quaternary. The former is the most prominent one. Zircon polychronism in mafic-ultramafic rocks in Tuva proves to be a persistent regional feature and, in most cases, corresponds to zircon populations rather than individual crystals. The results further demonstrate that the U–Pb age of zircon from zircon-poor mafic and ultramafic rocks cannot automatically match the host rock crystallization age. Robust interpretation requires differentiation between igneous, inherited, xenogenic, and overprinted zircon within an integrated petrochronological framework and comparison with independent geochronometers.

The paper examines the formation conditions and specifies the geological structure of the Upper Jurassic carbonate formation in the Bukhara–Khiva oil and gas region as one of key areas of hydrocarbon reserves concentration within the Central Asian oil and gas province. The paper summarizes and organizes materials from long-term geological exploration, lithofacies, paleontological, and stratigraphic studies, as well as utilizes data from deep drilling and regional tectonic analysis. The focus is on characteristics of sub-reef horizons XVI and XV, in addition to the Upper Oxfordian–Kimmeridgian reef and supra-reef deposits formed under conditions of the area's active tectonic evolution. The authors examine pre-reef deep-water, barrier-reef, and back-reef lagoon facies, their material composition, spatial variability, and relationship with paleorelief morphology. Reef buildups and related accumulative structures prove to be critical for the most capacious and permeable carbonate reservoir formation and are confined to zones of tectonic bends, flexures, and faults in the Paleozoic basement. The balance between the tectonic basin floor subsidence rate, sea level, and high biological productivity of reef-building organisms controlled the growth and spatial position of barrier and isolated reefs. There are grounds for activation of fault structures contributing to the formation of relative uplift areas where bioherm and reef buildups with improved reservoir properties developed, as well as zones of back-reef aprons and carbonate shoals. The applied facies analysis methods, lithological and petrographic, and paleontological studies refined the formation model of the Upper Jurassic carbonate formation in the Bukhara–Khiva oil and gas region.

The study assessed the significance of the Central and Western Bukantau Mountains ring structures for predicting gold ore mineralization, using remote sensing, geophysical, as well as geological and geochemical data. The paper is based on the 2018–2021 project for compiling a cosmo-geological structure diagram and a remote sensing map at a scale of 1 : 50,000 for an area of about 5,600 km2. Landsat-7 ETM+, Landsat-8 OLI, ASTER/Terra, Sentinel-2A, and QuickBird multi- spectral images were used together with aeromagnetic, gravity, and electrical survey data. The images were processed in ENVI, ERDAS IMAGINE, Geomatica PCI, ArcGIS, and LESSA software, involving color compositions, band ratios, PCA, IHS/ITS transforms, mineral and hydrothermal compositions, as well as computer-assisted lineament analysis. Visual and automated interpretation revealed a system of 21 ring structures different in terms of morphology. The most prospective sites were found to be peripheral and nodal parts of the ring structures associated with deep faults, intrusive exocontacts, and zones of hydrothermal alterations recognized by clay-mineral and iron indices. The comprehensive analysis of ring structures, lineaments, and spectral indicators of hydrothermal alteration proved to facilitate the Kokpatas-type gold ore mineralization prediction reliability. The identification of eight prospective sites with a total area of about 97 km² has become a practical outcome of the study performed.

The article reviews the current capabilities of unmanned aerial vehicle (UAV-based) geophysical methods for solving a broad spectrum of geological tasks, ranging from regional-scale mapping to shallow-depth investigations. The primary focus is on the authors’ novel UAV-based electromagnetic surveying technology aimed at exploring large areas (covering several hundred square kilometers) at depths of 500–800 meters. The authors concisely describe the methodology and equipment used. Case studies from multiple sites illustrate the practical application of the UAV-based geophysical system. The results demonstrate the potential of the proposed UAV-based technologies. Both international and Russian research efforts facilitate prospects for further development.

The paper presents development of the “Geochemistry processes” software module integrated in the QGIS geographic information system environment. This module enables the full cycle of geochemical data processing, including pre-processing, analytical data quality assessment, statistical analysis, and final visualization, with figures and maps automatically generated. The module field testing confirmed its effectiveness: it was proven to reduce time and labor costs, minimize errors, prevent from duplicated operations, and ensure workflow integrity. The solution proposed is of high practical value, contributes to development of digital methods in geology, and is ready to be integrated in geological exploration organizations’ operational processes.

The authors analyzed a sample of an ore rock from the unique Tomtor REE-Nb ore deposit, using scanning electron microscopy and energy-dispersive X-ray spectroscopy. A high rare earth element (REE) potential of the rocks should have been previously related to microorganisms’ activity and specific physical and chemical conditions of their habitat. To confirm the hypothesis, the authors conducted a bacterial and paleontological study of the goethite horizon (int. 58.0–58.1 m) rock sample from the borehole Г2 (Buranny site). The findings revealed microfossil remains of various morphologies in the rock sample, which correspond with rare earth element accumulation zones. The results described morphology of the discovered microfossils and identified both prokaryotic and eukaryotic forms. The study demonstrated that in the manganese iron oxide rock rare earth element accumulation occurs exclusively in microfossil remains, with the fossilization process involving replacement of the organic matter with plumbogummite-group minerals. It was determined that, during their lifetime, microorganisms in the studied sample primarily accumulated cerium and lanthanum, and to a lesser extent, praseodymium and neodymium, provided that the qualitative composition of rare earth elements relates to the fossilized microorganisms’ morphological type.

The paper reviews geological aspects of the Lekhta Structure (East Karelia) and characterizes the gold-uranium mineralization objects localized within the Sariolian conglomerates of the Zheleznye Vorota Formation (Zheleznye Vorota, Nigalma, Kala-Lampi, Lobash-Ruchey, and Varozero) and the Jatulian conglomerates and gritstones (Rigovaraka, Borovaraka, and Kichu-Lampi). Both gold and uranium mineralization were concluded to be formed within single ore-forming systems. The paper outlines the gold-uranium mineralization prerequisites and features (structural, lithological, hydrothermal-metasomatic, and geochemical), which can be considered as elements of geological exploration models used to identify gold ore objects in other Early Proterozoic structures of the Karelian–Kola region. The gold-uranium mineralization referred to the “gold-bearing conglomerate” formation was likely to be developed under Svecofennian tectonic-magmatic activation conditions which resulted in remobilizing, redepositing, and centralizing primary gold within strata prospective for gold and uranium. The author gives recommendations for further study of the Lekhta Structure gold potential, including those for identifying the zones of tectonic and hydrothermal-metasomatic alterations that control the gold-uranium object distribution, as well as for clarifying relationship between and sequence of gold and uranium mineralization.