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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 (∆Ta) 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.

The article presents algorithms for numerical modeling of electrical micrologging signals and calculation results in geoelectric models of impermeable rocks and the borehole environment of a porous, permeable reservoir. This research may be useful for developing an integrated approach to the quantitative interpretation of electrical logging data. A joint numerical analysis of electrical logs measured by conventional probes and microprobes will enable refining the radial electrical resistivity distribution in the borehole environment of oil-gas reservoirs. This, in turn, will provide additional information when jointly solving the problem of drilling mud filtration and numerical inversion of electrical logging data, resulting in a more accurate assessment of reservoir porosity and permeability. We have developed software for numerical simulation of electrical micrologging signals – those from a microgradient, micropotential and microlaterolog probe with focusing. We employ a finite element algorithm with an arbitrary position of the probes in a cylindrically-layered geoelectric model, and a finite difference algorithm for a microgradient and micropotential probe in a horizontally-layered model. Test calculations of the signals in geoelectric models of Western Siberia terrigenous deposits are presented. The models describe impermeable sediments as well as layers with the mud cake and invaded zone at different resistivity ratios. The model parameters correspond to Lower Cretaceous oil-gas reservoirs exposed with polymer-clay drilling muds. The analysis of the calculated micrologging signals reflects a small investigation depth of microgradient and micropotential probes, and a strong dependence of the signals on the drilling mud and mud cake resistivities. Numerical modeling in the class of a cylindrically-layered model has allowed us to obtain the radial resistivity change in the borehole environment of an oil-gas reservoir.

Experimental researches focusing on modeling of interaction between eclogitic and lherzolitic garnets with reduced and oxidized sulfur-rich fluids are conducted using multianvil high-pressure apparatus of “split-sphere” type (BARS). Experiments are carried out in garnet-sulfur-carbon and garnet-anhydrite-carbon systems at the pressure of 6.3 GPa and the temperatures of 1150, 1300, and 1450 °С in graphite ampules, as well as in Pt-ampules with hematite buffering container. It is experimentally demonstrated that interaction of both reduced and oxidized sulfur-rich fluids with mantle garnets leads to their partial dissolution and recrystallization, and to the formation of zoned crystals with decreased iron content in rims. Apart from that, this interaction also results in (1) garnet carbonatisation accompanied by formation of the magnesite±dolomite+kyanite+coesite assemblage, and (2) garnet sulfidation with formation of pyrite (1150-1300 °С) or sulfide melt (1450 °С) as inclusions in garnets and in interstitial space. As a result of conducted experimental researches it is established that indicatory characteristics of mantle garnets that underwent metasomatism by sulfur-rich agents, are decreased FeO content in peripheral crystal zones relatively to their centers, and formation of sulfide inclusion in the zones borders. In this paper we also present the first data on diamond dissolution in the silicate-sulfur-carbon systems under lithospheric mantle P,T-parameters that simulate mantle metasomatism of garnet-bearing lithologies by sulfur-rich fluids. It is found that under such conditions diamond crystals undergo partial dissolution resulting in formation of characteristic etching pits (negative trigons on {111} and rectangles on {100}).

Spectral decomposition is a widely used method of qualitative seismic interpretation, whose key limitation lies in the subjective selection of frequency components for visualization. Existing approaches based on the analysis of the integral Fourier spectrum do not account for the temporal localization of the signal’s spectral content. This study introduces a new method for the automatic selection of frequencies based on approximating local spectra obtained via the Short-Time Fourier Transform (STFT) with a sum 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 static set of frequencies over the entire interval. The optimization problem is solved using the differential evolution algorithm. The method was tested on data from fields of the West Siberian petroleum province. Quantitative evaluation using Shannon and Rényi entropy metrics, as well as a colorfulness metric, demonstrated increased informativeness of RGB images compared with traditional approaches. The proposed method reduces interpretation subjectivity and ensures reproducibility of results.

Experimental studies aimed at assessing the possibility of diamond crystallization during interactions of alkaline earth and transition metal carbonates with sulfur, as well as at characterizing the obtained diamond crystals and inclusions in them, were carried out on a multi-anvil high-pressure "split sphere" apparatus (BARS). The experiments were performed at constant P,T,t-parameters: 6.3 GPa, 1550 ºС and a duration of 20 hours, in the Mg,Ca-carbonate-sulfur system with different CaO/MgO ratios and Fe,Mg,Ca-carbonate-sulfur system with variable FeO/CaO/MgO proportions. It was experimentally established that in the alkaline earth carbonate-sulfur systems, a Ca,Mg-carbonate melt with dissolved sulfur (1.2-6.0 wt.%) is formed, which is a diamond growth medium. The stable growth form of diamond crystals is the octahedron, and an increase in the Ca# of the system is accompanied by an increase in the growth rate of the {111} faces. It was demonstrated that in the Fe,Mg,Ca-carbonate–sulfur system, the crystallization medium and the source of diamond carbon is the Fe,Mg,Ca-carbonate melt with dissolved sulfur, and diamond growth occurs as a result of the redox interaction of the sulfide and carbonate melts. With an increase in the ferruginousity of the system from 0.41 to 0.78, there occurs (1) an increase in the growth rate of the {100} faces (from 1.0 to 5.4 μm/h); (2) a change in the predominant elements of the octahedron face microrelief from triangular growth layers to hexagonal vicinals; and (3) an increase in the number and size of inclusions, as well as the evolution of their phase composition. Diamond inclusions are formed by melt preservation on the {100} faces during the transformation of a cuboctahedron into an octahedron. The inclusions contain quenched carbonate melt (quenching phases — carbonate, magnetite, and graphite), sulfur melt, and Fe-S-O melt. The discovery of a carbonate+magnetite+graphite association in the inclusions confirms the occurrence of a siderite redox dissociation reaction (3FeCO₃ = Fe₃O₄ + 3C⁰ + 2.5O₂ fluid) at the P,T-parameters of the lithospheric mantle. These results shed light on the possible origin of magnetite inclusions in upper-mantle diamonds and suggest that the presence of magnetite in syngenetic inclusions may be an indicator of the participation of iron-bearing carbonates in natural diamond formation processes. The results of the conducted studies indicate that Mg,Ca- or Fe,Mg,Ca-carbonate melts with dissolved sulfur can be classified as natural diamond-forming environments, and the identified features of the morphology of diamond crystals, the specifics of its growth and the composition of inclusions depending on the cationic composition of the carbonate melt with dissolved sulfur can be used as indicators of diamond crystallization in similar melts in nature.

This paper presents new evidence for fluorine enrichment in the diamond-forming mantle of the Siberian Craton. For the first time, we have discovered inclusions containing calcium and aluminum fluorides in diamonds from placers in the northeast of Siberia. In contrast to microinclusions in fibrous diamonds and coated diamonds, the inclusions we studied in diamonds from the northeastern Siberian Craton placers can be interpreted as fluoride melts. In diamond ISTD-119, inclusions are oriented parallel to the octahedron faces and can be considered syngenetic. At the same time, in diamond ISTD-124, an elongated inclusion is oriented parallel to slip lines. This provides grounds to believe that the formation of the inclusion was synchronous with the stage of diamond deformation. In variety V diamonds XLS-147 and ISTD-193, the morphology of inclusions located in the central parts of the crystals allows them to be interpreted as healed fractures. Within the inclusions, fluorine is present as compounds with calcium, having stoichiometry close to fluorite. The inclusions exhibit areas consisting of calcium fluorides and areas consisting of carbonates and/or iron oxides. In variety V diamond XLS-147, aluminosilicate inclusions and inclusions consisting of aluminosilicate and fluoride parts were identified. However, unlike inclusions in diamonds ISTD-119, ISTD-193, and ISTD-124, the fluoride part of the inclusions in diamond XLS-147 is represented by aluminum fluorides. There is a body of evidence for the growth of type V diamonds in a subduction zone. The compositional variations of the inclusions we studied indicate immiscibility of fluoride melts with aluminosilicate and carbonatite melts. The inclusions we have investigated testify to a fluorine-enriched diamond-forming mantle of the Siberian Craton at the time of diamond formation.

A thermodynamic model of the interaction between surface waters and the wastes of flotation enrichment of sulfide PGE–Cu–Ni ores from the ore region under consideration (Krasnoyarsk krai) is presented. The relevance of the study is determined by the need to assess the long-term stability of mineral associations. The aim of the work is to establish the patterns of transformation of mineral associations during long-term storage. The initial information was provided by mineralogical and chemical composition of samples from two pits, as well as the chemical composition of water extracts [Starostina et al., 2025]. Calculations were carried out in the solid–water–gas system under variations of Eh, simulating different degrees of system openness to atmospheric oxygen (standard T–P, pCO_2(gas) = 10^–3.5 atm). Based on the modeling results, it was found that pyrrhotite is stable under extremely reducing conditions (pO_2(gas) = 10^–79 atm), where the dissociation of water into atomic oxygen and hydrogen may occur. In general, the obtained models reflect the transition from sulfide to oxide–silicate associations with a decrease in the number of mineral phases as oxidation progresses. The modeled associations correspond well with mineral parageneses observed in polished sections. It was shown that the material retains its primary mineral structure even after decades of storage, which is explained by the high content of rock-forming minerals within a dense clay matrix that prevents oxygen and moisture from penetrating in amounts sufficient for intensive oxidation. The results obtained are recommended for use in the development of technological schemes for the recovery of potentially valuable metals from the flotation wastes of sulfide PGE–Cu–Ni ores.

This study synthesizes petrochemical, geochemical, and isotopic (Sm–Nd and Rb–Sr) data on granitoid and gabbroid complexes of the Western Sayan, formed in a range of geodynamic settings (including island arc, accretion–collision, transform–shear, and active continental margin environments) between the Late Vendian and Late Devonian. The results provide constraints on the physicochemical conditions of parental melt generation, the nature of magma sources, and their temporal evolution throughout successive geodynamic stages.

These findings highlight the long-term evolution of magma sources in response to changing geodynamic regimes during the Vend–Paleozoic development of the Western Sayan. The intrusive complexes display a systematic decrease in ɛNd and increase ⁸⁷Sr/⁸⁶Sr₀ values in granitoid and gabbroid complexes from early to later geodynamic stages: island arc (545–524 Ma, ɛNd = +7.5 – +4.9, ⁸⁷Sr/⁸⁶Sr₀ = 0.7042–0.7056), accretion–collision (505–460 Ma, ɛNd = +6.9 – +0.6, ⁸⁷Sr/⁸⁶Sr₀ = 0.7036–0.7041), transform–shear (437–433 Ma, ɛNd = +8.4 – +7.2, ⁸⁷Sr/⁸⁶Sr₀ = 0.7031–0.7057), and active continental margin (425–370 Ma, ɛNd = +5.7 – +1.0, ⁸⁷Sr/⁸⁶Sr₀ = 0.7035–0.7103). This progressive shift reflects a declining contribution of mantle sources (island-arc and oceanic types) and a concomitant increase in the role of ancient crustal components (metamorphic complexes, turbidites, and flysch-type sediments) in the generation of parental magmas.

The composition of volcano-terrigenous formations and age of detrital zircon from the tuff-turbidite series sandstones of the Dzhida zone of the Central Asian Orogenic Belt were studied. The sandstones of this formation, in terms of their mineralogical and petrochemical characteristics, correspond to feldspar graywackes and belong to the rocks of the first sedimentation cycle. The main volume of detrital material is represented by volcanics and, to a lesser extent, plagioclase grains. Relatively low values of chemical index CIA (58-68) indicate moderate or weak chemical weathering of lithic components, that is a low maturity degree of the detrital material formed due to the source rocks mechanical destruction. The distribution curve of U-Pb ages of zircon from sandstones of the tuff-turbidite series has a bimodal character with peaks at 530 Ma and 510 Ma. The studied rocks do not contain zircons of Neoproterozoic age. The greywacke composition of the studied rocks, the low maturity degree and the distribution of zircon grains U-Pb ages suggest the formation of these rocks in the forearc basin conditions due to the removal of material from local sources – Early Cambrian volcanic rocks of the Dzhida ensimatic island arc.

The parameters for arsenic removal from Dashkesan ore enrichment tailings, which contain cobaltine (CoAsS), erythrite (Co₃(AsO₄)₂⋅8H₂O) and arsenopyrite (FeAsS), by combustion method with soda (Na₂CO₃) have been investigated. The processing method consists of two stages: 1) tailing/soda/coal mixture (molar ratio 1 : 1 : 0.2) was combusted at temperature 750 °C and time (1-3 h), 2) the combusted material was dissolved at 90 °C for 1 h in water with a phase ratio of S/L = 1 : 5. It was shown that the amount of As₂O₃ decreased from 5.47-6.19 to 0.52-0.71 wt%. The change of arsenic-containing phases in raw materials and processed products were studied by XRD, SEM/EDS and DTA/TG analysis methods. As the results of XRD analysis, the following arsenic-containing phases have been found in the combusted material obtained at 750 °C: sodium arsenate (Na₃AsO₄), sodium oxoarsenate (Na₅AsO₅) and scorodite (FeAsO₄⋅2H₂O). The residue obtained after dissolution is enriched with cobalt (CoO - 4.43 %) and can be considered as initial raw material for cobalt extraction.