Research subject. Deposits and occurrences of calcareous tufa, spring waters with a mineralization of more than 1 g/dm ³. Aim. Identification of the minerageny features of continental carbonate formation. Materials and methods. An analysis of the chemical composition of spring waters database compiled on the basis of hydrogeological surveys conducted in 1966–1992 at a scale of 1:200 000 in the Perm Region and the Catalogue of Deposits and Occurrences of Minerals of the Perm Region. Interpretation of the digital elevation model to identify neotectonic elements. Results. A mineragenic model of continental carbonate formation was reconstructed, including: (a) mobilization of calcium by underground waters on lifted blocks composed of carbonate-and-sulphate evaporites and groundwater discharge in adjacent trough blocks favorable for the slow flow of surface water; (b) essentially chemical deposition of subaqueous calcareous tufa at the site of groundwater discharge mainly biochemical precipitation of aquatic calcareous tufa in the lake, oxbow lakes and mean dering rivers, favorable for the activity of plants and living organisms. Conclusions. The zoning of calcareous tufa deposits on a neotectonic basis was carried out. The greatest contribution of sulphate calcium waters to the formation of calcareous tufa deposits was shown. The maximum possible quantity of chemogenic and biogenic calcium carbonate that can precipitate from individual springs in 100 years was calculated, amounting to 0.0001–1 million tons

Research subject. Clay rocks (clay siltstones, shales and mudstones) of a number of Riphean stratigraphic units of the Bashkir megaanticlinorium, as well as the Vendian Shkapovo-Shikhan depression and the Kvarkush-Kamennogorsk megaanticlinorium. Methods. Calculation of α ^Al values based on the data on the bulk chemical composition of clay rocks and the analysis of their correlation links with the ratios (e.g., Th/Sc, (La/Yb)_N, etc.) of a number of trace elements that are indicators of rock composition in paleo-catchments. In this case, any statistically significant correlation between the alpha index values and the indicator ratios was considered to be a consequence of the control of the α index values by the rock composition in paleo-catchments, and vice versa. Results. For both relatively small (7–8 analyses) and medium (22 or more analyses) analytical datasets, quite different relationships were established between the α ^Al indices and the ratios of the elements – indicators of the composition of rocks that make up the paleo-catchments. Conclusions. Similar to many other exospheric lithogeochemical indicators, the use of α indices without analyzing the influence of various factors thereon does not provide correct information on the intensity of weathering

Research subject. Rocks of the Urukul-Pokrovsky rhyolite-trachyrhyolite complex in the Alapaevsk-Adamovsky structural-formational zone of the East Ural megazone form necco and dike-like bodies among early-middle Devonian volcanic and volcanic-sedimentary deposits. Aim. To determine the geodynamic regime of formation of these deposits based on their isotope-geochemical characteristics. Methods. The contents of petrogenic oxides were determined by X-ray fluorescence analysis using SRM-18 and EDX-900HS (Na₂ O) devices; the contents of rare elements were determined by the ICP-MS method using an ELAN 9000 analyzer. The isotope ratios of Rb and Sr were measured by a Neptun Plus multicollector inductively coupled plasma mass spectrometer and a Triton thermal ionization mass spectrometer. Results. The rock complex was found to comprise rare-porphyry trachyrhyodacites and rhyolites. These are high-potassium deposits with a potassium-sodium type of alkalinity, belonging to the ferruginous alkali-calcic series. They are characterized by high values of the alumina saturation index (A/CNK). The rocks are enriched in Rb, U, Th, Pb, Zr, and Y, exhibiting low concentrations of Sr and lanthanides. In terms of chemical composition (higher alkalinity, increased concentrations of Al and K, increased contents of Cs, Rb, Ba, Hf, Ta, Zr), the rocks differ from the associated abundant porphyry rhyolites of the Rudyanka Formation. In geodynamic diagrams, the points of rock compositions are located in the field of post-collisional formations, and the Y/ Nb value may indicate their plume-dependent nature. Conclusions. The Urukul-Pokrovsky complex might have formed under the conditions of local extension at the stage of rigid collision in the Early Permian

Research subject. Zircon of sandstones of the Basu Formation, Asha Series, Vendian, in the reference section along the Kukrauk stream (Southern Urals). Aim. To determine the age of rocks in the provenance based on U-Th-Pb (LA-ICP-MS) dating of zircon clastics. Materials and methods. In terms of color, detrital zircon grains were divided into three groups. Pale pink grains predominate (about 50%), and pink and colorless grains are present in equal proportions (about 20–30%). Zircon is mainly represented by rounded grains and single grains of a prismatic shape. According to the cathodoluminescence data, most grains retain traces of zonation. Results. The U-Th-Pb concordant ages dates of 166 detrital zircon grains are predominantly in the time intervals of 996–1029, 1079–1110, 1152–1191, 1200–1234, 1250–1324, 1331–1370, 1416–1438, 1447–1557, 1573–1666, 1756–1806, 1824–1874, 1889–1979, 1987–2015, 2022–2074, and 2661–2729 Ma. Individual grains have concordant ages of 579, 776, 2120, 2142, 2148, 2190, 2763, 2874, 2804, 2816, 2889, 2957, 3014, and 3203 Ma. Conclusions. The group of pink grains is dominated by a population of zircon of the Early Karelian and Archaean age, in colorless grains – Early Riphean, and in pale pink grains – Early and Middle Riphean. Among the grains of detrital zircon from the sandstones of the Basu Formation, there are zircons from local Ural sources (776, 1350–1800,   2000–3200 Ma). For clastic zircon with ages of 996–1320 Ma, the sources of demolition among the local feeding provinces have not been identified; however, they are known within the Sveko-Norwegian area in the north-west of the East-European Platform. This allows us to consider the igneous rocks of the Grenville (950–1220 million years) Sveko-Norwegian orogen as sources of zircon clusters over this time interval. The source of zircons with a dating of 579 Ma, closeto the age (573–577 Ma) of zircons from tuff layers in the Basu Formation itself, could be ash material from the explosive activity of volcanoes

Research subject. In the area of the northern closure of the Magnitogorsk megazone and the Main Ural Fault bordering to the west, the state geological maps distinguish the Balbuk complex. This complex includes numerous monzonite-syenite-granite intrusions. Their isotope age, determined at different times and by different methods (K-Ar, Rb-Sr, Pb-Pb, U-Pb), varies from 363 ± 21 to 250 ± 5 Ma, which requires a deeper analysis. The composition of these granitoids has been poorly studied; as a result, the origin and geodynamic position of the Balbuk complex remain un clear. Methods. The chemical composition of rocks was studied by X-ray fluorescence analysis and mass spectrometry with inductively coupled plasma. The Sr-Nd isotopy of rocks was studied using thermal ionization mass spectrometry. Results and conclusions. The results of a mineralogical and geochemical study involving Sr-Nd isotopy of monzonites and granites of several medium-sized and small intrusions of the Balbuk area (Sharip group, Balbuk, Aushkul, and Kamatal) are presented. Geochemical features and Sr-Nd isotope data (ISr = 0.70355–0.70422, εNd t = +3.95) allow us to connect the source of monzonite magmas with the lithospheric mantle and crust of the Magnitogorsk island-arc terrane reworked by subduction fluids (including metabasites of ophiolite associations and continental margin). The main source of granites ((⁸⁷ Sr/ ⁸⁶ Sr) t = 0.70355– 0.70545, εNd t = +3.5…+4.8) is the metasedimentary rocks of the Magnitogorsk terrane. The distribution features of various elements in rocks reflect the complex fractionation of the parental melts. Two   Rb-Sr isochron dates were obtained: for monzonite porphyry from the small massif of the Sharip group (354.2 ± 1.4 Ma) and granite porphyry of the Kamatal massif (304 ± 29 Ma). The age data allows us to link them with the dating of other granitoids of the northern part of the Magnitogorsk megazone (Akhunovo-Petropavlovsk, Verkhneural’sk-Kassel areas) and to distinguish here discrete stages of monzonite-syenite (363–346 Ma) and subalkaline granite (307–294 Ma) magmatism. Monzonite-syenite magmatism is associated with the early destruction of the Late Devonian–Early Carboniferous accretion-collision orogen, and granite magmatism records the onset of the Ural collision orogeny. The data obtained showed that the combination of all types of granitoids into a single complex is incorrect and that the Balbuk area should be singled out as one of the centers of long-term mantle-crustal interaction.

Research subject. Seawater, basalts, and products of their transformation. Aim. To assess the behavior of chemical elements, mineral assemblages, and mineral formation conditions during low-temperature seawater–basalt interaction, including the additional input of dissolved CH₄ and CO₂ to the system. Method. Physicochemical modeling of seawater–basalt interaction was conducted using the Selektor software in closed systems based on changes in the ξ = –lg(seawater–basalt – Sw/Bs) parameter. Results. According to the conducted physicochemical modeling of seawater–basaltic glass inter action (closed system), quartz, goethite, celadonite, chabazite, manganite, and gibbsite are precipitated at the fluid-dominated part of the model (ξ> 3) under oxidizing conditions. An increase in the relative amount of reacted basalt (ξ < 3) leads to a decrease in the Eh value and the replacement of goethite by hematite and magnetite in assemblage with pyrite, saponite, chlorite, and zeolites. The addition of CH₄ to the system during early diagenesis under slightly alkaline (pH≈ 10) and reducing conditions (Eh < 0) results in the formation of brucite, chlorite, chrysotile, and pyrite at low Fe concentrations in solution and the absence of quartz, goethite, and manganite. During late diagenesis under alkaline conditions (pH > 10), a significant Si and low Fe amount passes to the solution, while pyrite and magnetite dominate in the system in addition to saponite, chlorite, celadonite, chrysotile, and zeolites. The contribution of CO ₂ (1 mole/L) to the system significantly changes the model; thus, only chalcedony is precipitated at the early stages (ξ > 5) under acidic (pH < 3) oxidizing (Eh = 1) conditions. At reduced Eh values under acidic conditions (ξ = 2–3), the high Fe and Al content passes to the solution and strongly decreases under neutral and slightly alkaline (pH > 8) reducing conditions of late diagenesis. At the same stage, Mg silicates, magnetite, pyrite, and hematite are dominant; however, the Fe oxides do not form economic concentrations   in solid reaction products. Conclusions. In general, our results correspond to natural diagenetic products of basaltic glass.

Research subject. We study the specific features of distribution of minor and rare-earth elements in secondary quartzites and associated rocks of the Bolshoy Tyuters island. Secondary quartzites, quartz veins therein, and various iron-alumina metasomatites – potential sources of minerals – are considered. Materials and methods. The mineral composition and structure of secondary quartzites were examined using a JSM-5610LV scanning electron microscope. The U-Pb isotope system of zircon grains from two samples of secondary quartzites was studied in the Center of Collective Use, Laboratory of Chemical and Analytical Studies, Geological Institute of RAS, using an Element-2 mass spectrometer. Rare elements were determined by inductively coupled plasma mass spectrometry (ICP–MS). Results. The formation of secondary quartzites was shown to be accompanied by removal of not only macrocomponents but also selective removal of most trace elements, some of which could be concentrated in iron-alumina metasomatites. The distribution of rare earth elements in these rocks shows a relatively uniform pattern: (La/Yb)_n = 5–14, Eu/Eu* = 0.3–0.6, with the sum of REE in iron-alumina metasomatites being an order of magnitude greater than in quartzites. The behavior of lithium is of particular interest, the concentrations of which reach 420 ppm in iron-magnesian metasomatites. Conclusions. The results obtained indicate a fundamentally new type of lithium enrichment associated with the geochemically poorly studied secondary quartzite formation. Only chromium and, in particular, molybdenum and copper exhibit elevated concentrations in the studied quartzites, which may indirectly testify to the geodynamic setting of rock complex formation on the Bolshoy Tyuters island. This resembles the modern island-arc situation or post-folding orogeny, in which the main lithium reserves are concentrated solars (salt lakes) or rare-metal pegmatites and copper-molybdenum deposits.

Research subject. Primary platinum-group minerals from the gold placer of the Bolshoy Sap River (Middle Urals) in the southern frame of the Pervomaisk ophiolite-type massif. Methods. The chemical composition of minerals was studied by scanning electron microscopy (JEOL-JSM6390LV) and electron microprobe analysis (Cameca SX 100). The sulfur isotopic composition of laurite and erlichmanite grains was determined using a laser femtosecond ablation system (NWR Femtosecond UC with laser Pharos 2mJ-200-PPam and harmonics module HE-4Hi-A) attached to a MAT-253 mass spectrometer (Thermo Fisher Scientific). Results. A wide species composition of primary platinum-group minerals was revealed, represented by native minerals of the Os-Ir-Ru (osmium, iridium, ruthenium, rutheniridosmine) and Pt-Fe (by stoichiometry close to the composition of isoferroplatinum) systems, as well as Ru-Os sulfides (laurite, erlichmanite). Iridium grains contain isoferroplatinum lamellae, which are a product of solid solution decomposition, as well as the inclusions of cuproiridsite, Ru-bearing pentlandite, kashinite, and tolovkite. Inclusions in isoferroplatinum are represented by braggite, rhodium and palladium sulfides (Pd-Rh-S), and Pd-bearing (5.78 wt % Pd) native gold. Variations in the composition of natural hexagonal Os-Ir-Ru alloys reflect the presence of three trends (i.e., ruthenium, osmium-iridium, and osmium-ruthenium). The sulfur isotopic values of laurite and erlichmanite grains ((1.0–2.5) ±0.2‰) are consistent with derivation of sulfur from a sub-chondritic source, reflecting a minor contribution of crustal sulfur during mantle-crustal interaction processes. The prevalence of primary platinum-group minerals in placers from various platinum-bearing zones of the Middle Urals was analyzed. In the western Serov-Nevyansk zone, Os-Ir-Ru alloys of osmium-iridium and ruthenium trends are common, as well as Pt-Fe minerals of the tetraferroplatinum series PtFe – tulameenite PtFe_0.5 Cu _0.5 – ferronickelplatinum PtFe _0.5 Ni_0.5. Os-Ir-Ru alloys of the osmium-ruthenium trend were established only in the eastern Salda-Sysert and Alapaevsk zones. Os-Ir-Ru alloys of ruthenium and osmium-iridium trends, native iridium and isoferroplatinum are widespread. Conclusions. The wide species composition of primary PGMs in the placer is due to the polygenic nature of chromitites, which is typical of ophiolite massifs in the Middle Urals. The high-temperature Os-Ir-Ru alloys of the ruthenium trend, as well as Os-Ru sulfides, are associated with laterally secreted chromites in the dunite-harzburgite complex. Metasomatic and reactive metasomatic chromitites in the dunite-verlite-clinopyroxenite complex serve as sources of natural Os-Ir alloys of the osmium-iridium trend and Pt-Fe alloys. The highest temperature Os-Ir-Ru alloys of the ruthenium trend, as well as Os-Ru sulfides, are associated with lateral secretion chromitites in the dunite-harzburgite complex. Metasomatic and reaction-metasomatic chromitites in the dunite-wehrlite-clinopyroxenite complex serve as bedrock sources of natural Os-Ir alloys of the osmium-iridium trend, and Pt-Fe alloys. The most likely reason for the appearance of the osmium-ruthenium   trend in the chemical composition of natural hexagonal Os-Ir-Ru alloys is the recrystallization of primary high-temperature solid solutions during metamorphic transformations at lower temperature conditions and the change of the oxidative regime to a reducing regime.

Research subject. The distribution regularities of Ge and Ti impurities in gold-ore quartz. Materials and methods. The   quartz of the Darasun, Teremkinskoye, and Talatuy gold deposits of the Darasun ore field was studied. The gross contents of germanium (C _Ge) and titanium (C _Ti ) impurities in quartz were determined by the LA-ICP-MS method; the contents of substitutional Ge and Ti impurities in the crystal lattice of the mineral were studied by the EPR method. Results. A correlation between the gross concentrations of C _Ge and C _Ti in quartz was determined. This correlation can take the form of an inversely proportional or directly proportional relationship. In the former case, quartz during crystallization captures predominantly Ge ²⁺ ions, and, in the latter case, Ge⁴⁺ ions. A model according to which the entry of Ge2+ ions into quartz occurs through the formation of complex aluminum complexes GeAl ₂ O ₄ is considered. The disintegration of such complexes during the recrystallization of quartz leads to the removal of Ge impurity and the capture of Ti impurity. Conclusions. It is suggested that the ratio of the contents of Ge²⁺ and Ge⁴⁺ ions in quartz reflects their ratio in the mineral-forming solution and is associated with the oxidation-reduction environment. On this basis, the type of relationship between the gross contents of Ge and Ti impurities in quartz is proposed to be used as an indicator of mineral formation conditions.

Research subject. The aposkarn serpentinites of the Klara mine in the Pitkäranta mining district. Aim. Determination of mineral formation environments for serpentinites of the Klara mine. Materials and methods. In total, 45 rock specimens were studied using optical and scanning electron microscopy, electron probe analysis, powder X-ray diffraction, in frared spectroscopy, and differential thermal analysis. Results. Skarn diopside is replaced by antigorite, lizardite, chrysotile and talc, which intergrown in many cases. The forsterite skarn zone is transformed into chrysotile-antigorite serpentinites with humite-group minerals that are replaced by late lizardite. All serpentine is enriched with F; the concentration of this halogen ranges 0.7–1.8 wt % in lizardite from pseudomorphs after diopside and humite-group minerals, 2.1–3.0 wt % in chrysotile-antigorite and antigorite aggregates, and 2.5–4.6 wt % in serpentine filling cracks. Other minerals are represented by magnetite, fluorite, micas of the phlogopite-fluorophlogopite series, annite, chlorites, Mn- and Fe-containing dolomite, fluorapatite, sphalerite, and pyrophanite. Conclusions. Aposkarn serpentinites of the Klara mine were formed during two stages. (1) Predominantly lizardite serpentinites appeared during the late stages of the regressive skarnification process associated with the intrusion of early granites of the Salmi Batholith, as a result of hydration of forsterite and, partly, diopside. (2) The Li-F granite intrusion caused the re-development of the pneumatolyte-hydrothermal process. The influence of ≈300–480°C F-rich fluids led to the replacement of lizardite by antigorite and chrysotile with a high concentration of fluorine. With a subsequent decrease in temperature, late lizardite was formed due to the preserved skarn diopside and minerals of the humite group.

Research subject. The underground temperature anomaly created by a typical office building. Aim . To conduct theoretical and experimental studies of conductive heat losses from a building, including those to the underground environment. To assess the morphology and evolution of the underground temperature anomaly and additional heat storage in the sub surface. To evaluate the economic significance and environmental consequences of such a temperature anomaly. Materials and methods. Experimental data were collected by monitoring temperatures and heat fluxes along the internal and external surfaces of the main structural elements of the building of the Institute of Geophysics of the Ural Branch of the Russian Academy of Sciences (Yekaterinburg, Russia). These data were used to calculate the resistance to heat transfer (reciprocal of thermal transmittance) of the building structural elements, annual fluctuations in heat fluxes, and annual heat losses. Numerical simulation was used to describe the distribution, intensity, and evolution of the underground temperature anomaly. Results. The building loses 83% of its heat through external surfaces (walls, windows, roof), with only 17% being lost through the basement walls and floor. Over 40 years of the building operation, the total losses amount to 133 TJ and are determined by the low thermal insulation properties of its structural materials. According to the simulation results, the heat fluxes that penetrated the ground have formed an underground temperature anomaly, which has thus far spread to 15 m to the sides of the building and to 40 m into the depth (by the 2 K isoanomaly). The excess heat storage retained in the subsurface during the period of 40 years amounts to 3.2 TJ or 2.4% of the total conductive heat loss. Conclusions. Heat losses from buildings play a key role in the formation of underground urban heat islands, exceeding the climatic contribution of global warming by 36 times. At the same time, the economic importance of the thermal energy accumulated in the underground environment is low, and the environmental consequences of warming of the sub surface are negligible.