Search

Abstract— The Buluktaevskoe molybdenum–tungsten deposit is considered a close analog of W–Mo deposits within the large Dzhida orefield, in which the Pervomaiskoe molybdenum and Inkurskoe and Kholtosonskoe tungsten deposits are known. Fifteen ore minerals were identified in the molybdenum ores of the Buluktaevskoe deposit; in addition to molybdenite, they include sulfides (pyrite, galena, and chalcopyrite), tungstates (wolframite and scheelite), molybdates (powellite and wulfenite), and a relatively large number of minerals containing rare earth elements (REE), U, and Th (Th-bearing monazite, brannerite, thorite, and uraninite); among them are previously unknown minerals: fluorine-bearing thorium molybdate and minerals with compositions corresponding to rare mineral species, orthobrannerite and kobeite-(Y). Interrelations and specific chemical compositions of the uranium–thorium–rare earth element minerals are discussed. It was established that these minerals formed in the course of hydrothermal alteration processes, at the early (molybdenite) development stage of the Buluktaevskoe molybdenum–tungsten deposit.

Abstract The Ermakovo F–Be deposit, the largest Be deposit in Russia and one of the world’s largest deposits, is located in West Transbaikalia. The ores of the deposit are diverse in their morphology and composition; mostly there are phenakite–bertrandite–fluorite metasomatites after limestones. The origin of Be mineralization is related to the stock of leucocratic subalkali aegirine-bearing granites, the age of which corresponds to 224–226 Ma. The available age of ores of 225.5–219 Ma is close to the age of ore-generating granites. To specify the age of the ores, we determined the 40Ar/39Ar age of K-feldspar and, for the first time, of the Be mineral milarite, a K- and H2O-bearing Be silicate (KCa2(Be2AlSi12O30)·H2O), from different ore bodies of the Ermakovo deposit. The age spectrum of milarite (sample Er-17) has a stable plateau in the high-temperature part, which consists of four consecutive steps composing ~50% of the released 39Ar with an age of 182.5 ± 3.0 Ma. The age of K-feldspars is similar (169.8–170.6 Ma). The results of 40Ar/39Ar dating of minerals from ores of the Ermakovo F–Be deposit indicate that the processes of mineral formation occurred over a long period from 225 to 170 Ma.

The purpose of the research is to identify and study the features of mineral composition and formation conditions of ores of the Kholtoson tungsten deposit located within the Dzhida molybdenum-tungsten ore field (South-West Transbaikalia, Russia). The study employs a complex of mineralogical-petrographic and thermobarogeochemical methods. The molybdenum mineralization of the Dzhida ore field is confined to the apical part of the Pervomaisky stock (Pervomayskoye deposit), the tungsten mineralization is confined to numerous quartz veins in the western part of the ore field (Kholtoson vein deposit) as well as to the stockwork in the central part (Inkur stockwork deposit). The Kholtoson deposit occupies the western part of the ore field and is composed of numerous quartz veins localized mainly in the diorites of the Modonkul massif. Conducted works allowed to find out that the main gangue mineral is quartz; muscovite, potassium feldspar and carbonates are also present. Hubnerite is the main ore mineral of the Kholtoson deposit. In total, more than 20 mineral species have been identified including sulfides (pyrite, chalcopyrite, galena, sphalerite, bornite, etc.), sulfosalts (tetrahedrite, aikinite, stannite, etc.), oxides (scheelite, cassiterite), tellurides (hessite). According to the data of fluid inclusions study, calcium chlorides with an admixture of sodium and potassium chlorides predominate in the salt composition of oreforming fluids. The minimum temperatures of quartz deposition vary in the range of ~195–344 °С. Most of the homogenization temperatures determinations correspond to the range of ~250–300 °С. The presence of cogenetic fluid- and vapordominated inclusions in quartz from the ores of the Kholtoson deposit allows to estimate the fluid inclusion capture temperature range of 413–350 °C. The results of the studies carried out by the authors indicate that the main factors of hubnerite precipitation from hydrothermal solutions are changes in alkali-acid content and a temperature drop.

—The paper is concerned with a geochemical study of apoultrabasic metasomatites of the Ospa–Kitoi, Parama, and Ust’-Kelyana ophiolite massifs located in the southern folded framing of the Siberian craton. The isotope (O, C, H, Sr, and Rb) systems of dunites, serpentinites, nephrites, listvenites, and talc–carbonate rocks are studied. The isotopic composition of oxygen in olivines from dunites is characterized by δ18O = 4.6–5.5‰. The δ18O values of serpentinites (4.67–7.35‰) point to the mantle genesis of fluids and might have been inherited from ultrabasic rocks. Nephrites are slightly enriched in heavy oxygen isotope (δ18O = 6.13–9.54‰). This indicates that their fluid phase was transported from serpentinites and captured a small portion of the crustal component. The widest variations in δ18O values, from 8.12 to 17.46‰, are observed in minerals from listvenites. Carbonates from these rocks show a highly heterogeneous isotopic composition of oxygen (δ18O = 12.9–18.8‰) and carbon δ13C = –2.8 to +2.8‰). These rocks formed with the contribution of metamorphogenic fluids. According to the isotopic composition of hydrogen, the examined serpentinites are divided into two groups: with δD values specific to “magmatic water” (δD = –73.50 to –85.00‰) and those typical of meteoric fluids (δD = –151.90 to –167.20‰). The listvenites are characterized by low Rb and high Sr contents. Their 87Sr/86Sr values (0.70702–0.70971) indicate the contribution of a crustal source. The study of fluid inclusions in minerals from listvenites has shown that the rocks formed under relatively low-temperature conditions. The homogenization temperatures of fluid inclusions in quartz and magnesite from listvenites of the Ospa–Kitoi massif are 184–290 ºC and 122–182 ºC, respectively. In the Parama massif, the homogenization temperature of fluid inclusions in quartz is 130–170 ºC. The solutions that formed listvenites of the Ospa–Kitoi massif were slightly saline (TDS = 2.9–8.4 wt.% NaCl eq.), with NaCl and Na2CO3 being the main salt components.

The solubility of phenakite in aluminosilicate melts of various alkalinity was studied experimentally at T = 1000°C and P = 1 kbar in dry conditions and in the presence of 10 wt % H2O. The experiments were carried out on a high gas pressure vessel. The duration of the experiments was five days. The initial material was prefused glass of granite composition with different agpaiticity (1–1.5), as well as natural phenakite. The composition of the samples after the experiments was determined by means of electron probe X-ray spectral analysis, and the beryllium content was determined by laser ablation. It was found that the solubility of phenakite depends on the composition of the aluminosilicate melt, increasing with increasing agpaiticity ((Na + K)/Al). The Be concentrations in dry melts vary within 0.67–1.3 wt %, and in the presence of an aqueous fluid, 1.58–2.28 wt %. The experimental data obtained testify in favor of the concentration of beryllium in residual alkaline water-bearing melts. In this case, the content of beryllium in primary melts can be high enough to form large deposits of beryllium due to its extraction from relatively small magmatic bodies.

The article discusses the features of the composition, age, and genesis of gold–antimony mineralization of the East Sayan based on the example of the largest Tumannoe ore occurrence. It is shown that objects of this type are rare in the considered region. In the course of studies, it was found that stibnite, pyrite, and arsenopyrite predominate in ores; Bi minerals (tetradymite, cobaltite, native Bi), antimonides and sulfosalts (zinkenite, chalcostibite, aurostibite, tetrahedrite, and andorite), and three generations of native gold are also present. The mineralization contains gold–bismuth and gold–antimony ore assemblages, which are the evolutionary products of a single ore-forming system, during which a sequential decrease in the PTX parameters of ore deposition occurred, where temperatures decreased from more than 380 to 180°С. Sulfur activity decreased during ore deposition, which led to the deposition of alternating ore assemblages from simple sulfides to sulfosalts, in the direction of increasing deposited components, and to the formation of different generations of native gold with a gradual increase in fineness from early to late assemblages. The results of mineralogical–genetic and isotope–geochemical studies evidence the magmatogenic nature of gold–antimony mineralization. The isotopic age of parent granitoids, obtained by LA-ICP-MS zircon dating, is Early Ordovician; age values are 491–486 Ma. 40Ar/39Ar dating of muscovite from ore veins shows a relatively young age value (439 Ma), which is due to the influence of late tectonic and thermal events associated with the Early Paleozoic orogeny occurred at that time throughout the territory of the present-day East Sayan.

The paper discusses the results of petrogeochemical and geochronological studies of the Tainsky granitoid stock containing the Tainsky gold deposit in the East Sayan. The Tainsky granitoid stock intrudes through ultrabasites of the Ospa-Kitoi ultrabasitic massif. Granitoids are the part of the ophiolite cover which overlap Archean basement rocks of the Tuva-Mongolian microcontinent of the Archean foundation. Consistent isotopic age values in the range of 850–860 Ma obtained by three independent methods (U–Pb, Re–Os, 40Ar/39Ar) are evidence of the Neoproterozoic age of granitoid magmatism and its genetic relationship with gold–(±copper)–porphyry mineralization. The geological setting, geochemical characteristics, and age of the Tainsky granitoid stock allow us to attribute these rocks to the Neoproterozoic Dunzhugur island arc sequences. Isotopic age values obtained by Rb–Sr and 40Ar/39Ar methods characterized by lower closure temperatures of isotopic systems make it possible to distinguish several tectonothermal events at 650, 435, 339–333, and 280–223 Ma, reflecting difference stages of tectonic evolution of the Eastern Sayan segment of the Central Asian folding belt.

An Erratum to this paper has been published: https://doi.org/10.1134/S1075701523330012

This paper presents the analysis of diagnostic policy of 72 patients with cervical osteochondrosis and cervicobrachial syndrome. All patients were examined according to a single program, which included a specially designed questionnaire containing address data, diagnosis, history of life and illness, patient complaints, with a mandatory examination by a neurologist for the presence of compression of neural structures of the cervical spine with a detailed description of the local status and clinical and neurological syndromes. Patients underwent general spondylography of the cervical spine in the anteroposterior and lateral projections. For the diagnosis of segmental instability, functional spondylography was performed in the position of maximum flexion and extension and functional spondylography with burdening, which is based on mathematical modeling of the distribution of the vector force load system in the cervical spine under conditions of inclination of the head at an angle of 45° (flexion) and 15° (extension) with the weight on the head weighing up to 500 grams (putting a special device on the head). A mathematical formula for calculating the index of instability of the vertebral motor segment in the cervical spine is proposed. Sagittal balance of the cervical spine was studied with the correlative dependence of its indicators with the intensity of the pain syndrome according to standard spondylography and magnetic resonance imaging. Identified marker indicator of electroneuromyographic studies of the upper extremities - F-wave. Based on the obtained fundamental knowledge, an algorithm for diagnosing osteochondrosis of the cervical spine and cervicobrachial syndrome has been developed and scientifically substantiated.

—We present results of study of the chemical composition, formation conditions, and genesis of gold-bearing pyrite–pyrrhotite ores widespread within the ophiolite belts in the southeast of East Sayan. The study was performed at the Ol’ginskoe ore occurrence localized in the Ol’gino gold ore zone. Sulfide mineralization zones are composed of lenticular interbeds and bodies subconfoimable with the bedding of the enclosing schist strata. The ores are carbonaceous siliceous garnet–biotite schists variably enriched in sulfide minerals, mainly pyrrhotite, with impurities of other silicate minerals: tremolite, chlorite, albite, plagioclase, diopside, and epidote. In addition, sphalerite, chalcopyrite, pyrite, and arsenopyrite are present in small amounts in the ores. The established Р–Т conditions of ore metamorphism (T = 430–540 °C, P ~ 5 kbar) correspond to the lower boundary of the epidote–amphibolite facies. Thermobarogeochemical studies of fluid inclusions in vein quartz showed close temperatures (536–340 °C) but lower pressures, 200–800 bars, which indicates that the quartz vein formation was related to a pressure drop. The predominant salts of the fluid inclusions are Fe and Mg chlorides with Na and K impurities. The geologic location, structures, textures, and mineral, geochemical, and isotope compositions of the studied sulfide ores indicate their formation in submarine deep-water environments as a result of the activity of hydrothermal systems, analogues of “black smokers”, later subjected to metamorphism. During metamorphism, primary ores underwent mineral and chemical transformations: pyrrhotitization of pyrite, appearance and coarsening of native gold particles, and redistribution of components (Mn, As, etc). The low contents of gold and some ore-forming elements (Zn, Cu, and Pb) in pyrrhotite ores testify to the removal of these elements with a metamorphogenic fluid. The removed ore-forming components might have been a source of material for later gold–sulfide–quartz deposits of the Urik–Kitoi zone in East Sayan.

The gold-bearing deposits of southeastern East Sayan have been categorized according to mineral composition. The most important classification criterion is the composition of productive ore mineral assemblages specific to each of the distinguished types, whereas the use of other criteria results in the inevitable overlap of different structural, compositional, or genetic features of deposits. Eight mineral types of deposits have been determined, which characterize the main gold-bearing mineral ore parageneses: gold-polysulfide, gold-quartz, gold-telluride, gold-tetradymite, gold-antimony, gold-bismuth-sulfosalt, gold-pyrrhotite, and gold-fahlore. The regional metallogenic units are structural-metallogenic zones somewhat differing by the nature of mineralization. Thus, in the Bokson-Gargan metallogenic zone, the gold-quartz, gold-polysulfide, and gold-pyrrhotite types of deposits prevail, while in the western part of the zone, the gold-telluride and gold-bismuth-sulfosalt types are widespread. In the Ilchir zone, gold-fahlore deposits are developed, while in the Khamsarinskaya zone, gold-tetradymite and gold-stibnite. It has been established that the mineral types of deposits depend on the composition of the host rock complexes: gold-quartz, gold-polysulfide, and gold-pyrrhotite types form in association with ophiolites and Archean basement rocks. At granitoid-massif-related deposits, base-metal minerals assume the leading role: Bi sulfosalts, stibnite, tetradymite, and tellurides. The gold-fahlore type forms in carbonate sequences. The proposed classification makes it possible to group all of the known gold-bearing deposits of southeastern East Sayan; it can also be applied to adjacent regions.

In this paper we report on investigation of the viscoelastic and rheological properties of early synthesized and characterized nanosuspensions by acoustical method, allowing to obtain the characteristic curves of shear elastic moduli and to assess the degree of "hardening" and structuring of the suspension. The paper is rising the question of fundamental problem - the structuring the nanosuspension, that might shed a light on the possibility of "engineering" the structure of a liquid by controlling and regulating the degree and nature of intermolecular interaction.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X22340013

This study examines the compositions of the ore and the ore formation solutions, conditions of formation, and sources of Be mineralization using the Aunikskoye F-Be deposit, which is an integral part of the Western Transbaikal beryllium-bearing provinces, as a representative example. Further, the main factors responsible for the formation of beryllium mineralization were evaluated. The ore deposits are presented by the feldsparic–fluorspar–phenacite–bertrandite metasomatites formed in the carboniferous limestones during their metasomatic alternation with hydrothermal solutions by introducing F, Be, and other associated elements. The formation of early phenacite–fluorspar association occurred in high-fluorite СО2-containing solutions of elevated alkalinity with a salinity of ~10.5%–12% wt eq. NaCl in a temperature range of ~ 370–260 °С at pressures ranging from 1873 to 1248 bar. More recent fluorite and bertrandite deposits were formed by solutions with a salinity of 6.4%–7.7% wt eq. NaCl in a temperature range of ~156 °C–110 °C and a pressure range of 639–427 bar. The examination of the isotopic signature of the ore association minerals confirmed the apocarbonate nature of the main ore deposit and allowed the determination of the magmatogene nature of the ore-forming paleothermal springs, which are the source of subalkaline leucogranites. The primary factors that influenced the formation of the F-Be ore included the reduction of the F activity in solutions because of the binding of Ca and F in fluorite as well as because of the decrease in temperature during the ore deposition process. The elevated alkalinity of the ore-formation solutions resulted in the low solubility of the Be complexes, which caused a relatively low Be content in the ore and a relatively small amount of mineralization in the deposit.

Techniques for the simulation of thermodynamic processes in molecular systems are proposed. The results of the calculation of the argon isothermal compressibility by the molecular dynamics method for isobar cooling from 200 to 15 K at a pressure of 40 atm and an adiabatic compressibility in the range of 200–160 K at 40 atm are given. Steps, interpreted as phase transitions, are visible on the temperature dependences of the isothermal compressibility at fast (1012 K/s) and relatively slow (109 K/s) cooling.

The paper presents the results of studying of the ore composition, ore-forming solutions, formation conditions, and sources of Be mineralization based on the example of the Aunik F-Be deposit, which is part of the Western Transbaikalia beryllium-bearing province; the main factors responsible for the beryllium mineralization are also assessed. The ores of the deposit are represented by feldspar-fluorite-phenakite-bertrandite metasomatites that formed after carboniferous limestones during its metasomatic replacement by hydrothermal solutions bearing F, Be, and accompanying admixture elements. It is established that the early phenakite-fluorite assemblage formed from high-fluoride CO2-bearing solutions with high alkalinity and a salinity of ~10.5–12 wt % NaCl eq. in the temperature range ~370–260°C at pressures from 1873 to 1248 bar. Later fluorite and bertrandite were formed by solutions with a salinity of 6.4–7.7 wt % NaCl eq. in the temperature range of ~156–110°C and pressure range of 639–247 bar. Isotopic composition studies of the ore assemblage minerals have confirmed the apocarbonate nature of the main ores at the deposit, making it possible to establish the igneous nature of the ore-forming paleohydrothermal solutions, the source of which were subalkaline leucogranites. The main factors controlling the formation of F-Be ores were the decrease in F activity in solutions owing to bonding of Ca and F in fluorite and the reduction in temperature during ore deposition. The increased alkalinity of the ore-forming solutions controlled the low solubility of Be complexes, which resulted in a low Be content in ores and a relatively small-scale mineralization at the deposit.

The paper discusses the geology of Zun-Ospa gold deposit, which is situated near the Ospino ophiolitic nappe in the southeastern part of the Eastern Sayan, and the ore composition therein. The deposit is related to the tectonic melange zone and is characterized by distinct structural control. Three consecutive mineral assemblages formed within a temperature range of 380°–170°C: (i) native gold–quartz–pyrite, (ii) gold–quartz–polysulfide, and (iii) silver–sulfosalt. The ore was deposited from low-concentration (5.2–14.2 wt % NaCl equiv.) solutions without CO2, with the predominance of Mg and Fe chlorides and an admixture of Na and K chlorides. The major ore minerals are pyrite, chalcopyrite, galena, and sphalerite; identified subordinate minerals are pyrrhotite, pentlandite, heazlewoodite, fahlore (tennantite, freibergite), Ni and Ag sulfosalts (ullmannite, miargyrite, polybasite, stephanite), Ag sulfides (mckinstryite, argentite); Au minerals are represented by electrum, kuestelite, and native gold of medium to low fineness. The geological, mineralogical, geochemical, and isotopic characteristics of ore indicate a metamorphic–hydrothermal genesis of mineralization related to the formation of a melange zone in the duplex strike-slip structure. The sources of ore components are host rock complexes that have been subjected to tectonic deformations, among which rocks of an ophiolitic association predominate, along with fragments of initial hydrothermal–sedimentary ore, granitic, terrigenous, and carbonate rocks. The Late Paleozoic (352 Ma) age of mineralization corresponds to the stage of postcollision shear deformations within the entire Central Asian Foldbelt.

This article presents new data on the age of the largest gold deposits in the southeastern part of Eastern Sayan. The dates have been obtained by Ar–Ar analysis of micas occurring in gold-bearing quartz veins and mineralized zones. The obtained Ar–Ar ages of fuchsite and sericite from the tectonized and mineralized zones of the Zun–Holba deposit (ore body Severnoye-3), range within 353.9–386.4 Ma; a similar result of 352.9 Ma was yielded by Ar–Ar dating of Cr–muscovite from mylonitized listvenite in the veins of the periphery of the Zun–Ospa gold deposit. However, muscovite from the ore-bearing quartz vein of the Pioneer gold–quartz deposit, located near Zun–Holba, has been dated to 421.9 Ma. The obtained new data on isotopic age of the gold–quartz ores and gold–sulphide–quartz deposits allow recognition of the Early Palaeozoic accretion–collision and the Late Palaeozoic shearing stages of formation of gold mineralization in the SE Eastern Sayan.

In the Ospin–Kitoi ultramafic massif of the Eastern Sayan, accessory and ore Cr-spinel are mainly represented by alumochromite and chromite. Copper–nickel mineralization hosted in serpentinized ultramafic rocks occurs as separate grains of pentlandite and pyrrhotite, as well as assemblages of (i) hexagonal pyrrhotite + pentlandite + chalcopyrite and (ii) monoclinal pyrrhotite + pentlandite + chalcopyrite. Copper mineralization in rodingite is presented by bornite, chalcopyrite, and covellite. Talc–breunnerite–quartz and muscovite–breunnerite–quartz listvenite contains abundant sulfide and sulfoarsenide mineralization: pyrite, gersdorffite, sphalerite, Ag–Bi and Bi-galena, millerite, and kuestelite. Noble metal mineralization is represented by Ru–Ir–Os alloy, sulfides, and sulfoarsenides of these metals, Au–Cu–Ag alloys in chromitite, laurite intergrowth, an unnamed mineral with a composition of Cu3Pt, orcelite in carbonized serpentinite, and sperrylite and electrum in serpentinite. Sulfide mineralization formed at the late magmatic stage of the origination of intrusion and due to fluid–metamorphic and retrograde metasomatism of primary rocks.

Our paper reviews a series of relatively low-grade gold deposits and prospects hosted by granitoid intrusions within the southeastern East Sayan in the Altaid Belt (northern Central Asian Orogenic Belt, Russia). The studied deposits/prospects are characterized by the presence of Te-, Sb- and Bi-bearing minerals. However, they differ in their main gold-associated mineral assemblages, which permits to distinguishing four mineralization assemblages: 1) gold-telluride; 2) gold-tetradymite; 3) gold-stibnite; and 4) gold-bismuth sulfosalt. The gold-telluride mineralization (1) is represented by the Tainskoye deposit, and the Khoringolskoye and Sagangolskoye prospects which are defined by paragenesis of native gold with Au-Ag-Bi-Pb-Ni tellurides, such as hessite, petzite, altaite, wehrlite, calaverite, melonite, altaite, and tellurobismuthite. The gold-tetradymite mineralization (2) which is represented by the Konevinskoye deposit, is hosted by the Saylag granitoid pluton, and contains tetradymite as one of the principal minerals associated with native gold. The gold-stibnite mineralization (3), represented by the Tumannoye prospect, is also hosted in a granitoid complex consisting of granodiorite and leucogranite. The gold-bismuth-sulfosalt mineralization (4) is documented at the Pogranichnoye prospect, where native gold is associated with the bismuth-bearing minerals: bismuthinite, galeno-bismuthite, lillianite, and native bismuth. Estimated δ18O values of ore-forming fluids from intrusion-hosted deposits range from 5.7 to 7.4‰, indicative of a magmatic origin; δ34S values of sulfides vary from −4.2 to 4.5‰, which corresponds to magmatic sulfur. The geological setting, element geochemistry of host granitoids, stable isotope ratios, and mineralogy of the studied deposits are consistent with a magmatic origin of the mineralizing fluids. The studied deposits are spatially associated with either Neoproterozoic or Early Paleozoic granitoids, belonging to the two main orogenic stages of the East Sayan geodynamic evolution. At ∼850 Ma, during the Neoproterozoic stage, deposits with dominant gold-telluride assemblages, formed in association with granitoids characterized by geochemical features of island arc granites. During 458–439 Ma, in the Early Paleozoic stage, gold-tetradymite, gold-stibnite, gold-telluride and gold-bismuth-sulfosalt assemblages were formed that are spatially associated with orogenic granites with different geochemical compositions. Most gold-bearing mineral assemblages are intersected by post-mineral Late Paleozoic dykes. The origin of these different gold-sulfide-telluride assemblages is explained with their genetic association with granitoid intrusions of different ages and compositions.

Following the fundamental work by Bazaron, Bulgadaev and Derjaguin [6] on the observation of shear elasticity of low viscous liquids, we build on this study by examining viscous liquids, polymers and suspensions of nanoparticles. In this paper, we review our past and current efforts in these areas. The mechanical properties of liquids, polymers and nanosuspensions have been studied at relatively low frequencies of 105 Hz. The real and imaginary shear moduli of these samples were obtained on equipment using the acoustic resonance technique. It was shown that the shear modulus and viscosity decreases with increasing shear deformation. The behavior of viscoelastic fluids near surfaces is similar to that of colloidal and polymer suspensions, suggesting that the liquid component is determined by the mechanical response of suspensions.

The article discusses the composition of studied ore-forming solutions and the P-T conditions of molybdenum mineralization in the Pervomaisky stockwork deposit which is situated within the Dzhidinsky ore field (South-Western Transbaikalia, Russia). New geochronological data of zircons from granites, muscovite, and molybdenite from the ore zones indicates the association of the granite formation and ore deposition processes which occurred 119&ndash, 128 million years ago. Quartz-molybdenite veins of the Pervomaisky deposit were formed at the temperature of &ge, 314&ndash, 186 &deg, C with some boiling periods. Fluid inclusions in these veins have total salt concentration of 6.3&ndash, 12.7 wt. % NaCl equivalent (eq. NaCl). The salt solution is composed of chlorides of Na, Ca, K, and Fe. The gas phase contains CO2, CH4, and N2. A series of elements were determined in fluid inclusions by laser ablation (LA)-ICP-MS: Li, Be, B, F, Na, Mg, Al, Cl, K, Ca, Mn, Fe, Cu, Zn, Nb, Mo, Ag, Sn, La, Ce, Ta, W, Au, Pb, Th, U. The Mo content reaches 559 ppm (average of 228 &plusmn, 190 ppm) in high-grade quartz-molybdenite veinlets, whereas Mo content is up to 212 ppm (average of 25 &plusmn, 29 ppm) in the low-grade veinlets. High-grade veinlets were formed by near-neutral solutions with a higher content of Mo, S, and F, while relatively low-grade veinlets were deposited from alkaline solutions. Our results demonstrate the pH of the solutions as one of the key factors for ore deposition.

This article discusses the peculiarities of mineral composition and a fluid inclusions (FIs further in the text) study of the Kholtoson W and Inkur W deposits located within the Dzhida W-Mo ore field (Southwestern Transbaikalia, Russia). The Mo mineralization spatially coincides with the apical part of the Pervomaisky stock (Pervomaisky deposit), and the W mineralization forms numerous quartz veins in the western part of the ore field (Kholtoson vein deposit) and the stockwork in the central part (Inkur stockwork deposit). The ore mineral composition is similar at both deposits. Quartz is the main gangue mineral, there are also present muscovite, K-feldspar, and carbonates. The main ore mineral of both deposits is hubnerite. In addition to hubnerite, at both deposits, more than 20 mineral species were identified, they include sulfides (pyrite, chalcopyrite, galena, sphalerite, bornite, etc.), sulfosalts (tetrahedrite, aikinite, stannite, etc.), oxides (scheelite, cassiterite), and tellurides (hessite). The results of mineralogical and fluid inclusions studies allowed us to conclude that the Inkur W and the Kholtoson W deposits were formed by the same hydrothermal fluids, related to the same ore-forming system. For both deposits, the fluid inclusion homogenization temperatures varied within the range ~195–344 °C. The presence of cogenetic liquid- and vapor-dominated inclusions in the quartz from the ores of the Kholtoson deposit allowed us to estimate the true temperature range of mineral formation as 413–350 °C. Ore deposition occurred under similar physical-chemical conditions, differing only in pressures of mineral formation. The main factors of hubnerite deposition from hydrothermal fluids were decreases in temperature.

This study provides geochemical, mineralogical, and isotope data for rocks and ores from Lower Proterozoic black shale formations of the Kodar–Udokan structural and formational zone, which host the Khadatkanda gold—uranium deposit. The results indicate that the uranium and gold mineralizations were formed at different times in relation to different geodynamic settings. The gold mineralization is associated with the inception of the Syulban fault and has a juvenile source. The later Th–U mineralization originated during tectonic rejuvenation of the Syulban fault zone, while the sources of radioactive elements were presumably the underlying sediments of the Kodar Group, which are widespread throughout the area of the Baikal mountain region (BMR). Based on the above results, the Au–U mineralization in the study area can be recognized as unconformity-type deposits, analogous to the well-known deposits of Australia and Canada. In this connection, the Baikal mountain region has a good potential for the discovery of Au—U deposits.

The Konevinsky gold deposit in southeast Eastern Sayan is distinguished from most known deposits in this region (Zun-Kholba, etc.) by the geological setting and composition of mineralization. To elucidate the cause of the peculiar mineralization, we have studied the composition, formation conditions, and origin of this deposit, which is related to the Ordovician granitoid pluton 445–441 Ma in age cut by intermediate and basic dikes spatially associated with metavolcanic rocks of the Devonian–Carboniferous Ilei Sequence. Four mineral assemblages are recognized: (1) quartz–pyrite–molybdenite, (2) quartz–gold–pyrite, (3) gold–polysulfide, and (4) telluride. Certain indications show that the ore was formed as a result of the superposition of two distinct mineral assemblages differing in age. The first stage dated at ~440 Ma is related to intrusions generating Cu–Mo–Au porphyry mineralization and gold–polysulfide veins. The second stage is controlled by dikes pertaining to the Devonian–Carboniferous volcanic–plutonic association. The second stage is characterized by gain of Hg and Te and formation of gold–mercury–telluride paragenesis.

Experimental results of studying low-frequency (74 kHz) shear elasticity of polymer liquids by the impedance method (analogous to the Mason method) are presented. A free-volume thick liquid layer is placed on the horizontal surface of a piezoelectric quartz crystal with dimensions 34.7 × 12 × 5.5 cm. The latter performs tangential vibrations at resonance frequency. The liquid layer experiences shear strain, and shear waves should propagate in it. From the theory of the method, it follows that, with an increase in the layer thickness, both real and imaginary resonance frequency shifts should exhibit damped oscillations and tend to limiting values. For the liquids under study, the imaginary frequency shift far exceeds the real one, which testifies to the presence of bulk shear elasticity.

The structure and formation conditions of beryllium ore, as well as the fluorite and fluorite–microcline bodies at the Snezhnoe deposit in Eastern Sayan have been revealed and studied using geological, mineralogical, petrographic, and thermobarogeochemical methods. It has been established that the stringer and breccia ores were largely formed as a result of filling of open cavities (voids and fissures) rather than of replacement of low-Ca host rocks. Three types of high-grade ore consist of almost the same set of minerals in different proportions. Calcium and fluorine necessary for fluorite formation in three main types of ore have been supplied with the near-neutral high-F solutions (type I) and the solutions of elevated alkalinity (II, III types) in the form of complex compounds like Na2CaF 4 0 , Ca2Cl3F0, etc. Beryllium minerals were deposited within a temperature interval from ≥340 to 230°C due to the cooling of the solution and binding of F into fluorite with the breakdown of Be fluorine complexes and intense deposition of Be minerals.

The shear elasticity of different fluids are studied experimentally at relatively low frequencies of 40 and 74 kHz. The real and imaginary shear moduli of several liquids are measured using the acoustic resonance method. A low-frequency viscoelastic relaxation process is assumed to occur in a fluid with a period of relaxation much longer than the lifetime of the individual fluid particles.

The study objects are the Khadatkandskii fault zone, the Khadatkanda gold–uranium deposit confined to it, and sediments of the Kodar (Ikabi, Ayan, and Inyr formations) and Chinei (Chitkanda, Aleksandrovka, and Butun formations) groups located at significant distance from the above-mentioned area. Complex geophysical and geochemical studies of rocks and ores are performed. The obtained geochemical and mineralogical data indicate that the Khadatkanda gold–uranium deposit can be ascribed to the infiltration–epigenetic type. It is established that the uranium and gold mineralizations were formed at different times in relation to different geodynamic settings. The gold mineralization is related to the formation of the deep-seated Syulbanksii fault and has a juvenile source. The later Th–U mineralization originated during tectonic rejuvenation of the Syulbanksii fault zone, while the sources of radioactive elements were presumably the underlying sediments of the Kodar Group. This is confirmed by isotope studies. Metasomatically altered rocks with elevated Au content have δ34S from +2 to +4‰ CDT, which is 4‰ lighter than the sulfur isotope composition of the U-bearing samples (from +6 to + 8‰).

Results of experimental investigation of the low-frequency shear elasticity of liquids depending on the angle of shear strain are presented. A cluster model of the liquid structure is suggested to explain the low-frequency viscoelastic relaxation.

Low-frequency complex shear modulus of the colloidal suspensions of nanoparticles Nd:YAG in ethylene glycol was measured for the first time by using acoustic a resonance method with piezoquartz vibrator. Dependence of viscoelastic properties of the colloidal suspensions on nanoparticles sizes and their concentrations has been carried out.

The Pogranichnoe ore occurrence of gold-bismuth type is closely related to Ordovician granitic rocks pertaining to the Sarkhoi granodiorite-granite complex of calc-alkaline series. This type of mineralization in the Eastern Sayan is described for the first time. The orebodies are represented by quartz veins and veinlets with greisenized granite as selvages. Three mineral assemblages consecutively follow one another: (1) pyrite-arsenopyrite, (2) base-metal with fahlore and Sb sulfosalts, and (3) gold-bismuth. The geological position of orebodies and character of microinclusions in accessory minerals of granites suggest that goldbismuth mineralization is related to granitoids.

The shear moduli of liquids and their dependence on the degree of purity of the piezocrystal surface are measured by acoustic resonance method using a piezoelectric quartz resonator. As a criterion of surface condition the coefficient of static friction is accepted, which is measured by tribometer of Derjaguin–Lazarev design. The various methods of surface treatment which give a wide range of friction coefficients are used. At the maximum value of the coefficient of friction vibrating piezoquartz surface is completely wetted by the liquid and the effective value of the shear modulus of the liquid is the highest.

The shear modulus and mechanical loss tangent are measured for several liquids in the frequency region between 104 and 105 Hz. It is found that an increase in frequency is accompanied by a decrease in the shear modulus and an increase in the mechanical loss tangent.