Acid volcanism (rocks with silica more than 64 wt%) is the most widely represented in the orogenic volcanic belts (continental margin and kollisional) and ensialic island arcs on the continental stage in their development. At an early stage of formation of these structures acid volcanics are part of differentiated series basalt-andesite-dacite-rhyolite formation, at a later stage they form bimodal (contrasting silica) formation of high alkalinity. The heyday of acid volcanism coincides with middle-orogenic stage as rhyolite-rhyodacitic eruptions, often in the form of ignimbrites. Variations of the the content of potassium and sodium in rocks are changing in different stages. The most constant ratio of potassium and sodium are characterize for middle-orogenic volcanics while early and especially later-orogenic volcanic rocks vary widely in content of these parameters. In general, the acid volcanic orogenic belts more alkaline and potassium than rock ensialic island arcs, except sometimes occur at the front of orogenic belts of small island- structures ultrapotassic rhyolites. Petrochemical peculiarities of volcanics vary considerably across the strike of orogenic belts. Low-potassium branch of calc-alkaline series dominated in the frontal zones, the rocks of high-K branches of this series as far as shoshonite-latite petrochemical series developed in the rear areas of orogenic belts. The emergence of acid volcanic rocks in a large volume and their alkalinity correlated with the maturity of the continental crust, with an overall impact on the granite-metamorphic layer heat a deep basaltic magma, transmagmatic fluids and reomobilized of “crust” volatile components.

For the first time we carried out a detailed comprehensive study of Frasnian stage in the lower сurrent of the Malaya Usa River located within the Eletskaya structural-formational zone of the Polar Urals. The Middle-Late Frasnian age of these rocks was determined by conodonts in the sequence from hassi-jamieae to Late rhenana of standard conodont zones. We analyzed the distribution of conodont biofacies in the section. Polygnathus-Ancyrodella biofacies is most developed in the interval of the hassi-jamieae zones. We found increasing biodiversity of conodonts and prevalence of deep-water Palmatolepis biofacies in the interval of the Early rhenana-Late rhenana subzones. We studied the material composition and secondary changes in the carbonate rocks of the section, which allowed reconstructing primary sedimentary structures and sedimentation environments. In general, the deposits were formed within a narrow intra-shelf depression, to which intra-basin clastic material actively entered. At some intervals of time, more deep-water clay-carbonate sedimentation conditions, which were associated with the global eustatic events at the jamieae-Early rhenana (Semichatovae transgression) and Early rhenana-Late rhenana (Lower Kellwasser transgression) are noted. The analysis of isotope-geochemical data presented that the early stage of the Semichatovae transgression corresponded to a slight shift in the isotope ratio of carbon from 1.5 to 1.8‰, after which the isotope composition lowered to 0.4‰. The subsequent variation changes from 0.8 to 1.7‰ gradually decreased, reaching the value of 0.9-1.0‰. At the level of the Lower Kellwasser transgression, a slight positive shift in the isotope ratio of carbon from 0.1 to 0.7 with subsequent variations in the range of 0.5-0.7‰ is noted. Similar changes in the isotope composition of carbon at the event levels of Semichatovae and Lower Kellwasser are observed world-wide and mostly developed in the sections of Central and Southern Europe, North America and North Africa.

The images of the species of conodonts from the section of boundary Artinskian-Kungurian deposits on by right to coast Yuryuzan River near the village Mechetlino are given and commented. The stratigraphic distribution of species in the section is shown, their changes are analyzed. Text is accompanied by ten tables with the images of conodonts. The forms from the upper part of Artinskian (Sarginskian horizon) of the section depicts in the table I. These species of conodonts Neostreptognathodus ruzhencevi Kozur and N. pequopensis Behnken are meeting the most frequently in the Sarginskian horizon. Quantity of pairs of nodules in the Sarginskian representatives of the species N. pequopensis Behnken rarely exceed 4-6, moreover the posterior pair of nodules frequently grows together. The species Sweetognathus somniculosus Chern. is found in the Sarginskian horizon too. The morphology of the specimens of this species varies from the morphotypes, which possess almost one-piece carina, hardly by noticeable narrowings at the posterior end, to the forms with the distinctly differentiated posterior end of carina. Conodonts, depicted in the Table II, occur from the bad 9, in upper part of which the forms N. pnevi Kozur et Movschovitsch and N. lectulus Chern. are found. These species are the indicators of lower boundary of Kungurian stage. Forms in the Table III of the bed 10 and majorities of the depicted forms relate to the species N. lectulus Chern. The species N. labialis Chern. with narrow platform, incomplete developed middle groove and with the outlined narrowing in the posterior part of the platform here for the first time appears. The typical N. ruzhencevi Kozur continue to be encountered in the bed 10. Forms on the Tables IV-VII relate to the most representative complex of conodonts from the upper part of the bed 12, where more than 60 the specimens of conodonts found. The large part of the specimens, placed in the Table IV, relates to the phyletic sequence of forms from Sweetognathus somniculosus Chern. to N. labialis Chern. The forms, which relate to the species Neostreptognathodus pnevi Kozur et Movschovitsch, N. lectulus Chern., N. pequopensis Behnken in the Tables V, VI are represented. The members of phyletic line Neostreptognathodus pseudoclinei Kozur et Movschovitsch - N. labialis Chern. presents in the Table VII. The composition of conodonts in the subsequent informative beds 13, 14, 16 of the Saraninskian horizon remains. Conodonts of the Philippovskian horizon found west of quarry Mechetlino. They are represented in the Table X: Neostreptognathodus aff. clinei Behnken, N. clinei Behnken, Sweetognathus nov. sp. 2 , Uralognathus cochleatus Chern. Section Mechetlino is recommended as limitotype of lower boundary (GSSP) of the Kungurian stage of the International stratigraphic scale.

The Kulinda section belongs to the base of the Ukurey Formation in the Orlov Depression (Transbaikalia). The site has yielded numerous bones and associated integumentary structures belonging to the primitive ornithischian dinosaur. However, the age of the Kulinda deposits has not been investigated in detail so far. Palynological studies discussed in this paper clarify this question and provide the data on the palaeoenvironments. The Kulinda section is composed of siltstone and sandstone with admixture of volcanogenic material. Ten samples were collected from the bone-bearing deposits as well as the underlying and overlying sediments. The samples were treated by 15% hydrochloric and 30% hydrofluoric acids. Mineral and organic matters were separated by centrifugation in cadmium heavy liquid with specific gravity 2.25. Spore-pollen assemblage contains the species, which are important for Middle Jurassic stratigraphy: Podocarpidites rousei Pocockand, Eboraciato rosa (Sachanova et Iljina) Timochina. Their lowermost occurrences are revealed in the Bathonian in Western Siberia (Palynozone 10) and Kansk-Achinsk basin. The domination of Pseudopicea variabiliformis Bolchovitina and abundant Cyathidites are also characteristic features of the Bathonian of Western Siberia. Palynological zones in this region are calibrated against ammonite Boreal standard and foraminiferal successions that give the reliable age constraints. Spore-pollen assemblage from the Kulinda section shows that neighboring areas were occupied by coniferous forests with an admixture of pteridosperms, podocarpaceans and ginkgoaleans. More humid habitats near the lake were mostly occupied by cyatheaceous/dipteridaceous ferns. The climate was temperate and rater humid. The water genesis of deposits is confirmed by the presence of green algae Botryococcus and Leiosphaeridia. The age of the Ukurey Formation was broadly regarded as the Late Jurassic according to palaeontological data, isotope dating and its general position in the section. New palynological data show that its lower stratigraphic extend is wider, than it is was assumed earlier, and changed over the territory. The Bathonian age of the Ukurey Formation does not contradict to the general geological situation in Transbaikalia. Biofacial analysis confirms lacustrine genesis of the Ukurey Formation and evidences temperate warm and rather humid conditions on the nearby land areas.

The totality of structural-tectonic, lithologic-mineralogical, isotope-geochemical data on the geology of Primorye and adjacent territories of Northeast China and the Amur Region allows us to justify the criterions for the existence of an ancient sialic crust in its foundation. The main of them are the following. 1. Mesozoic terrigenous rocks of the Sikhote-Alin folded formations are characterized by the Proterozoic model age, with more ancient for arkoses - to 2460 Ma (T_NdDM₂). They are composed mainly of granite-metamorphic mineral association and have zircons reaching the age of up to 2500 Ma. The terrigenous flysch is arkose-dominant. 2. Тhe territory of South-Western Primorye, is covered by Cenozoic basalts with Proterozoic model ages and anomalously low isotope ratios of lead [Pb²⁰⁶/Pb²⁰⁴], analogous to basalts developed on the ancient AR-PR₁ lithospheric blocks. 3. Structural deformation tectonic plan reflects presence of a single ancient rigid foundation of the territory with conformly react to a change of the compression-tension regimes in long time cycles. 4. The abundance of potassium- and barium-rich magmatism with geochemical characteristics of kimberlites-lamproites very spread within Primorye and Amur Region. A similar type of magmatism is not typical for areas with juvenile crust and reflects the presence of the mature continental lithosphere. Since the late Proterozoic, the sialic crust of Primorye has been consistently degraded as a result of delamination and basification processes.

Granitoids of Ishirim anticlinorium which is one of the major Precambrian structures of the North Urals, are poorly studied by modern geochemical and isotope-geochronological methods that led to the existence of different points of view on formation conditions and age of these rocks. The authors performed a study of the composition of rocks from three massifs - Vels, Moiva and Pos’mak, by chemical analysis and ICP-MS; age determination on zircons by the methods of LA-ICP-MS and SHRIMP, as well as the study of the composition of rock-forming and accessory minerals using microprobe SX-100, which allowed us to obtain fundamentally new data about the age, fluid regime of formation and potential ore content of granitoids. It is shown that the granitoids were probably formed in environments of active continental margin and orogen; the first has the Ediacaran (567.2-558 Ma), the second - Cambrian (530.3-511.1 Ma) age. Discrete intervals of the formation and a fairly significant geochemical differences of Precambrian and Paleozoic granites, allow to attribute them to different complexes - the Ediacaran Moiva complex and Cambrian Vels complex. The complexes are different in composition of fluids which change over time from substantially chlorine to fluorine. With more ancient (Ediacaran) granitoids of Moiva massif can be associated gold-bearing Mo-W mineralization, and with Cambrian granites - rare-metal mineralization (W, Nb, Ta, REE).

The unusual Bi-Ni mineralization, represented by parkerite, millerite, bismutohauchecornite, bismuthinite, nickeline and, possibly nickel analogue of smythite (?), found in the metasomatically altered chromite rocks of the Mariinsky emerald-beryllium deposit is described. Chromitites with Bi-Ni mineralization are found in the mica complexes in direct connection with serpentinite bodies., Polished sections from the selected chromite samples were examined with the CAMECA SX 100 electron probe microanalyzer (IGG UrB RAS). In the study of sulfide and arsenide mineralization, the accelerating voltage was 15 kV, the electron beam current - 30 nA, the duration of intensity measured at a peak was 10 sec, at the background was 5 seconds, the diameter of the analysis point was 2 μ. For microprobe analyzes, the following standard samples were used: pure metals (Bi, Ni, Co), alloys (GaSb) and sulphides with arsenides (pyrrhotite, sphalerite, InAs). The formation of the studied unusual Bi-Ni mineralization in metasomatically altered micaceous chromite ores of the Ural Emerald Mines is directly related to the formation of rare-metal pegmatites of the nearby Aduiskiy granite massif. The acidic fluid flow associated with the introduction of pegmatite veins transformed not only the chromite bodies, but also the serpentinites, which containing them, with the formation of talc-carbonate and talc-anthophyllite rocks, mica rocks and other high-temperature apohyperbasite metasomatites. This fluid, enriched in Be and F, which superimposed on the chromite matrix, that formed such unusual metasomatic mineral paragenesis as chromite, muscovite-aluminoseladonite, fluorophlogopite, tourmaline (fluorodravit-dravite), mariniskite-chrysoberyl, fluorapatite, eskolaite, zircon, sulphide, chromferide and native metals. The source of bismuth certainly was acidic fluids, nickel is contained in the hyperbasites themselves, sulfur and arsenic could be from hyperbasitic intrusions (they often contain impregnations of millerite, hizlewoodite and mauherite) and from granitoid ones. Such mineralization is typical for sulfide copper-nickel ores and hydrothermal veins of a five-element formation, in ophiolite bodies and associated chromite rocks such mineral association was not observed. The discovery of bismutohauchecornite is the first, and parkerite - the third in the Urals. Formation of Bi-Ni-mineralization took place in the temperature range from 300^oC to 200^oC.

The paper presents the results of a study of the chemical composition of the sulfosalts of bismuth from the gold-quartz-sulphide ore Berezovsky Deposit and the eponymous ore district of the Middle Urals. Samples of minerals were obtained from quartz veins located in different parts of the ore area. In the South of the district the veins occur among the granites of the Shartash massif and accompanied by the metasomatic gumbeit formation. Veins in its Central part are located into the dikes of granite porphyry, volcanic-sedimentary rocks, hyperbasites. In the North, the veins are localized in gabbro, hyperbasites, volcanic rocks. Here, as in the Central part, they are accompanied by metasomatic changes of the berezite-listwanite formation. The minerals of bismuth form small isometric, prismatic or needle-shaped secretions, as well as large elongated crystals reaching a length of several centimeters. Their diagnosis and study of the composition was performed by X-ray structural and chemical microanalysis. It is shown widespread among minerals of bismuth sulfosalts of the bismuthinite-aikinite series, consisting of 9 members: bismuthine, pecoite, gladite, stroking, salzburger, krupkaite, lindströmite, khammarite, fridrikhite and dramatically prevalent among sulfosalts that number aikinite. In mineral composition pavonite series revealed cuprapawonite, Cu-benjaminite, benjaminite. Other sulphosalts of bismuth are presented kosalite, nafildite, hodrushite, matildite. The relationship of minerals with each other and the peculiarities of the chemical composition allowed to distinguish several paragenetic associations conform with different stages of mineral formation. With high-temperature stage (360-285°C) connects the deposition of disordered solid solutions bismuthine-aikinte and pavonite series, subsequently undergone to disintegration with the formation of ordered phases of bismuthine, gladite, krupkaite, lindströmite, khammarite, benjaminite. For medium and low temperature stage (285-150°C) was formed aikinite, fridrikhite, krupkaite, salzburgite, nuffieldite cozalite, matildite, together with the Ag-Bi-Galena, tetradymite, hessite and gold. The low-temperature stage is associated with the formation of aikinite together with Galena and gold. Established on the example of the sulfosalts of bismuth sequence of mineral formation reflects not only the consistent evolution of mineral-forming fluids, but the pulsed nature of the hydrothermal activity at individual deposits and at ore field in general.

The Avzyan gold region is located within the Bashkirian anticlinorium and includes lode gold deposits and placers. The Gorny Priisk, Bogryashka and Ulyuk-Bar gold deposits are hosted in the Riphean metamorphosed carbonaceous sequence. The article describes the mineralogy of the heavy concentrates from alluvial sediments of the streams of Bolshoy Avzyan basin which drains the Gorny Priisk, Bogryashka and Ulyuk-Bar gold ore deposits. The comparison of mineralogical and chemical feature of the studied heavy concentrates is done. Samples and Methods. Samples from the streams were collected every 50-100 m. Hand specimens of ore and host rocks from the lode gold deposits were collected from outcrops and dumps. The content of metals in the heavy concentrates estimated using X-ray fluorescence analyzer Innov-X alfa. Chemical composition of the accessory minerals was studied using electron microscope Vega-3 Tescan with EDA X-Act Oxford. Discussion and Results. The source of the alluvial sediments was the lode gold deposits located in the immediate vicinity of placers. Heavy concentrates of the Kamenny stream are characterized by a high content of As and Cu while ones of the Bogryashka and Bolshoy Klyuch streams show a high content of Cr and Ba. Goethite is major ore mineral for all studied samples. Ilmenite, rutile, epidote and barite are also widespread in the samples from the Bogryashka and Bolshoy Klyuch streams. Native gold is present in the sediments of all studied stream. The greatest number of gold grains was found in the samples from the Bolshoy Klyuch stream. The weak roundness of the golds and the presence of unoxidized sulfides (pyrite, chalcopyrite and pyrrhotite) indicate a relatively small age of placers. Monazite and xenotime morphology suggests autigenic catagenetic and/or metamorphic origin. Monazite contains (apfu) Ce (0.27-0.56), Nd (0.10-0.37) and La (0.09-0.33), minor Pr, Sm, Gd, Eu and Dy; ThO₂ up to 9.78 wt. % (0.08 apfu). It is similar with monazite composition from other streams of the east part of the Bashkirian anticlinorium and can be evidence of their similar origin. Xenotime contains major Gd, Dy and Er and minor Tb and Ho. Xenotime from the Bogryashka stream is characterized by the increased concentration of (apfu) Gd (0.10-0.24), Nd (0.01-0.02), Sm (0.03-0.06), Eu (0.02-0.06) and absence of Ho and Yb. Xenotime composition from the Kamenny and Bolshoy Klyuch streams is similar with ones from east part of the Bashkirian anticlinorium. Galena inclusions in REE phosphates, monazite inclusions in goethite and xenotime inclusions in pyrite can be evidence about similar conditions and time of formation gold-sulfide and REE mineralization.