Research subject. Sandstones and clay rocks of the Lower, Middle, and Upper Riphean (the Kyrpino, Serafimovo, and Abdulino groups, respectively) of the Kamsko-Belsk aulacogen. Changes in the characteristic values of the ratios of a number of oxides and some trace elements that are the indicators of rock composition in paleowatersheds are considered, taking the hiatuses of different nature and duration into account. Methods. An analysis of the average values of  K₂O/Al₂O₃ etc., Th/Sc, La/Co and (La/Yb)_N, characteristic of sandstones and fine-grained clastic rocks (shales, fine-grained clayey siltstones and mudstones) of the main lithostratigraphic units of the Riphean section, as well as an analysis of their changes given the position below and above the break surface. Results. Throughout the entire Riphean, regardless of breaks in sedimentation associated with certain rearrangements in the recharge and sedimentation areas, the lithogeochemical characteristics of both sandstones and fine-grained clastic rocks (K₂O/Al₂O₃, TiO₂/Al₂O₃, Th/Sc, La/Co, etc.) were found to experience no signi ficant changes. Conclusions. The hiatuses presented in the Riphean section of the Kamsko-Belsk aulacogene were unlikely to have any significant effect on the average values of a number of ratios–indicators of rock composition in paleowatersheds (K₂O/Al₂O₃, SiO₂/Al₂O₃, TiO₂/Al₂O₃, Th/Sc, La/Co, and (La/Yb)_N) in sandstones and clay rocks occurring below and above the hiatus surfaces. This suggests that there were no cardinal changes in the composition of rocks in the paleowatersheds surrounding such a large negative structure as the Kamsko-Belsk aulacogene during the Riphean. Similarly, no fundamental changes occurred in the pathways of clastics entering the sedimentation area associated with the named structure.

Research subject. Carbonate-siliciclastic deposits of the Lower Uk Subformation were thoroughly studied in the section along the Yuryuzan river (near Ust-Katav town, Chelyabinsk region) and correlated with subformation sections along the Basu, Zilim and Bolshoy Inzer rivers. Material and methods. A detailed description of the stratotype section was carried out; sandstones, siltstones and limestones were studied in thin sections. The sections were correlated with each other. Results. Relationships between the Lower Uk Subformation and the underlying deposits are studied. The petrographic characteristics of rocks are presented. The Lower Uk Subformation sequences are traced between sections of various structural-tectonic zones of the Bashkirian Mega-anticlinorium (BMA). Conclusions. The set of features supports the idea about the presence of a sedimentary hiatus at the base of the formation, even in the most complete sequences (which contain the locally developed Shubino Member of the Minyar Formation). In the stratotype and in other reference sections, the Lower Uk Subformation has a pronounced three-membered structure; it is subdivided into the lower (siliciclastic) Yamashta, middle (substantially carbonate) Akkostyak, and upper (siliciclastic-carbonate) Avdyrdak members. The lithofacies analysis results suggest a change in environments from coastal-marine siliciclastic to shallow-marine siliciclastic-carbonate (middle and inner ramps) due to fluctuations in the relative sea level and, probably, climate change. It was established that the area of the Suleimanovo anticline at latest Riphean corresponded to the distal sedimentary environments in comparison with the southern and western zones (Alatau anticlinorium) of the BMA.

Research subject. The Upper Carboniferous-Lower Permian rocks of the Losinoostrov Formation of the Belsk-Eletsk structural-formational zone, exposed on the left bank of the Kozhim river, near the mouth of the stream Northnichael of the western slope of the Subpolar Urals. Methods. Optical and electron microscopic methods (including cathodoluminescence), chemical silicate, carbonate and X-ray diffraction analyses. Results and conclusions. The studied rocks are assigned to three main groups: mixtolites (rocks of mixed composition), carbonatoliths, and silicytolites with varieties.  Mixtoliths consist of three and four main components: carbonate, silty, argillaceous and siliceous. The variable ratio of rock-forming components of mixtolites was clearly reflected in the discriminative modular diagram. Here, fields of predominantly siliceous and silty mixolites (cluster I), predominantly argillaceous (cluster III), as well as transitional mixolites (cluster II) are identified. Relatively pure and silty-argillaceous-siliceous limestones were distinguished among carbonatoliths. According to the formed elements, pure limestones are divided into bioclastic and peloid-micritic. Silicytolites are represented by (1) radiolarites and radiolarian spongoliths; (2) silty-argillaceous silicytolites and (3) cherts (secondary siliceous formations). The established quantitative ratios of rock-forming components showed that more than half of the studied mixtoliths are composed mainly of the material of extrabasinal origin. Relatively high contents of extrabasinal fine material in carbonatoliths indicate a periodic decrement of the hydrodynamic regime during the accumulation of the upper part of the formation. The studied deposits were probably formed in distal and proximal ramp settings.

Research subject. Quartzites that make up the ridge part of the ridge Rosomaha in the northern part of the Lyapinsky meganticlinorium in the Subpolar Urals. Material and methods. Detrital zircons were isolated from quartzites and their optical and isotope-geochronological U-Pb (LA-SF-ICP-MS) studies were performed. On the basis of chemical analyzes of rocks using indicator ratios and coefficients, the conditions for the formation of deposits were established. Results. The stratigraphic position of the quartzite ridge Rosomaha was determined. The time and conditions for the formation of the Khobeinskaya formation were specified. The role of polymetamorphic complexes of the Subpolar Urals as possible sources of terrigenous material removal during the formation of the Upper Precambrian section of the Subpolar Urals was estimated. Conclusions. It was established that the quartzites belong to the ridge Rosomaha to the Khobeinskaya formation, whose age is limited to the interval of 850–800 Ma (Inzersky level). It is shown that the crystalline complexes of Fennoscandia and the Central Russian orogen, as well as polymetamorphic complexes of the crystalline basement of the Timan-Severoural margin of the East European Platform, could be sources of terrigenous material.

Research subject. Minerals of palladium, platinum, and native gold, localized mainly in the veins of chromium-containing mica (fuchsite) in rhyolites. Aim. Clarification of the localization features of platinum group minerals, their species diversity, determination of the composition of minerals, relationships between precious metal minerals, establishment of the sequence of formation. Methods. Polished sections from ore samples and concentrates of heavy minerals mounted in epoxy resin were studied using optical and electron microscopes. The composition of minerals was determined using a scanning electron microscope with an energy dispersive spectrometer. Results. The main Pd minerals of the deposit are isomertieite/pseudomertieite and mertieite, the minor ones are ateneite and the unnamed Pd₆BiSe mineral, and the platinum mineral is sperrylite. Isomertieite/pseudomertieite forms intergrowths with gold of any composition and structure, while mertieite occurs only with relatively low-copper gold of a homogeneous structure; therefore, significant areas of ore zones are characterized by the presence of one of the palladium arsenoantimonides. In some areas of ores, the replacement of isomertieite/pseudomertieite by mertieite wass established. Conclusions. The formation of fuchsite veinlets and the native gold, palladium minerals, and sperrylite contained therein is associated with one stage of mineral formation. Cr, Au, Pd, and Pt in ores form a single geochemical association, which indicates a common source of these elements. This source is most likely to be derivatives of basite-hyperbasite magmatism.

Research subject. The Tessemsky granite massif is located in the North Taimyr tectonic zone, surrounded by Cambrian rocks. The Pekinsky granite massif is located within the Central Taimyr zone, surrounded by metamorphosed Proterozoic rocks. Aim. To develop a methodology for using the composition of accessory granitoid minerals when prospecting  Cu-Mo-Au-porphyry mineralization on the example of the Pekinsky and Tessemsky granitoid massifs of the Taimyr Peninsula. Materials and methods. Accessory zircon and apatite contained in two granitoid samples from the Pekinsky massif (P1, P2) and two granitoid samples from the Tessemsky massif (T2, T3) were studied. Their mineral composition was examined using an EPMA Cameca SX100 instrument. The element content in minerals was determined by LA-ICPMS using an NexION 300S instrument equipped with an NWR 213 attachment. Results. Most of the zircons from the Pekinsky and Tessemsky massifs were formed at T < 738°C in oxidized magma with ΔFMQ of 0.6–2.6, which is a favorable sign for the identification of Cu-Mo-Au-porphyry mineralization. Zircons are characterized by elevated (Eu/Eu*)Y and  (Ce/Nd)_n/Y ratios, which is also a favorable, though not a strongly reliable, sign for identifying porphyry mineralization. The Eu/Eu* and Sr/Y ratios in the apatites from the Tessemsky massif are higher than those in the apatites from the Pekinsky massif. The rock compositions of both massifs fall within the fields of adakites on the classification diagrams. The estimates of oxygen fugacity (logfO₂) calculated from Mn in apatites for four samples agree well within the error limits.  Conclusion. Specific features of using the composition of accessory minerals (zircon and apatite) for prospecting the  Cu-Mo-Au-porphyry mineralization associated with granitoids were considered. Accessory indicator minerals can be used to rank granitoid massifs in order to assess their ore content. The example of two granite intrusions of the Taimyr Peninsula made it was possible to show that the Tessemsky massif is more promising for the discovery of associated Cu-Mo-Auporphyry mineralization than the Pekinsky massif.

Research subject. The subsurface thermal field in the city of Ekaterinburg (subsurface urban heat island). Aim. To determine criteria for the anomaly of mean annual subsurface temperatures in Ekaterinburg; to identify patterns of spatial distribution of underground temperatures; to quantify the main factors forming an urban heat island and changes in the heat content of rocks using mathematical modeling. Materials and methods. The main experimental data were obtained during the annual cycle of geothermal studies in observational boreholes of Ekaterinburg (22 boreholes) and surrounding areas (10 boreholes in Degtyarskiy, Verkh-Sysertskiy, Gagarskiy districts). Statistical analysis and mathematical modeling describing the impact of climate, local temperature anomalies of ground surface, and groundwater filtration to the underground thermal field were used when interpreting the obtained data. Results. At a depth of 20 m, the mean annual temperatures being less than 5°C and more than 6°C should be considered as anomalous. The maximum intensity of the urban heat island in Ekaterinburg is confined to densely built-up central areas of the city. The highest temperatures (>10°C) at a depth of 20 m are observed in boreholes located near buildings or directly therein. Here, a rapid decrease in temperature with depth is typical. Moderate anomalies from 6°C to 10°C are observed far from buildings. Remoteness from the central regions apparently plays a more important role in the formation of temperature anomalies than the type of urban surfaces (asphalt, concrete, lawns). Background temperatures (less than 6°C) were recorded in boreholes located outside the Ring Road.  An analysis of patterns in the attenuation of annual temperature variations with depth allowed an area with intense vertical filtration (up to 24 m/year) to be identified near the City Pond. The most significant changes in heat content in the range of 10–50 m are associated with heat leakage from the basements of buildings, equaling to (23–46) × 10⁷ J/m². However, this heat is only hundredths of a percent of the total energy consumption spent on heating. Conclusions. The subsurface urban heat island of a large Russian city has been characterized for the first time. The results obtained can be used when developing a strategy for megacities in changing climate conditions.