Research subject.Sphalerite (ZnS) is a widespread mineral that can be found in various depositional environments. During formation, this mineral can accumulate minor and trace impurities, with gold being one of the most valuable component. The issue of the chemical state of Au in sphalerite has been much discussed recently.Methods.Samples of In-, Fe- and In-Febearing sphalerite with a composition ranging from 0 to 2.5 mol.% In2S3 and 0 – 40 mol.% FeS were synthesized in an Ausaturated system using gas transport and salt flux techniques. The resulting products were subsequently investigated using EPMA and LA-ICP-MS.Results.All the elements under investigation are found to be homogeneously distributed within the sphalerite matrix. After quenching, sphalerite is shown to retain Au. Our data indicates that the observed increase in Au concentration is caused by the presence of In (up to 1.02 wt % Au) and, to a lesser extent, by that of Fe (up to ≈600 ppm Au). These elements substitute Zn in the crystal structure of sphalerite following the scheme Au+ + In3+(Fe3+) ↔ 2Zn2+, which is in good agreement with previous data obtained using the XAS method.Conclusions.A higher sulphur fugacity in the system leads to a more significant accumulation of Au in sphalerite. The concentration of Au in pure sphalerite does not exceed 10 ppm under our experimental conditions and does not depend on the activity of sulphur in the system.

Research subject. The deep structure of the Yugan-Koltogor zone located in West Siberia was investigated with the purpose of detecting prospective oil and gas bearing areas.Materials and methods. The methods of lineament extraction and the computer modelling of rock density were employed. Lineament extraction was conducted on the basis of geophysical data, including detailed (1 : 200 000) maps of anomalous magnetic and gravity fields. In order to detect faults, telemetering methods were used, along with the results of studies conducted to investigate core materials from wells in the region. The modelling of the deep structure of the pre-Jurassic basement was performed on the basis of its geological map by solving a direct problem while fitting geological body densities.Results. Six largest faults of the Yugan-Koltogor zone identified on the geological map by a special sign “deep faults and regional schistosity zones” are of particular interest as possible oil bearing areas.Conclusions. The modelling of the deep structure of the pre-Jurassic basement of the West Siberian Platform has shown the granite decompaction areas of the Yugan zone to be highly promising in terms of oil and gas deposits.

Research subject. The inner structure, composition, and genesis of the poorly studied formation of weathering crusts are studied with reference to peneplaned platform territories in Kazakhstan and Siberia during the Cretaceous-Paleogene boundary epoch. This formation hosts many valuable minerals, such as bauxite, iron ores, refractory clays, etc., thereby attracting much research attention. Materials and methods. The results were obtained following a series of long-term studies and a review of available data recently obtained on the weathering crust formation in the territories of Kazakhstan and Siberia. The methods of lithological facies and formation analysis were used, along with the separate studies of the eluvial material – weathering crusts in erosion areas and intra-formation weathering horizons in accumulation areas. Results. The weathering crust formation in the study area is shown to comprise two kinds of rock mass: siliceous-kaolinite ones forming erosion-tectonic depressions and kaolinite-bauxite ones forming karst depressions. The inner structure, composition, and genesis of both rock mass units are studied in detail, with all their sedimentation stages being analyzed. The sedimentation process is traced from the preparation of the material in weathering crusts at erosion areas to the deposition of this material and its post-sedimentation transformations (mostly with the involvement of subaerial diagenesis) in depressions. Detailed information is presented on subaerial diagenesis, which deserves further studies. Conclusions. This publication is the frst to present detailed information on the inner structure, composition and genesis of the ancient formation of weathering crusts produced in hot humid climate on peneplaned land territories. It is confrmed that the processes underpinning this formation – starting with the preparation of the material and ending with its accumulation in depressions – were different from those typical of modern orogenic environments. This conclusion extends the current understanding of the forms and nature of ancient lithogenetic processes.

Subject of study. Different points of view on the concept of structures of the terrain type and their role in the addition of orogenic belts are considered. Materials and methods. We used our own research and analysis of the latest publications about the Ural-Timan region and the Pacific belt, on the territory of the Northeast segment of Eurasia, as well as currently known isotope radiometric data. It was used also the result of geophysical seismotectonic and paleomagnetic explorations. Results. It has been established that in the composition of the Ural-Timan structural area, along with the Proterozoic and Paleozoic associations of the orogenic belts and the Riphean sedimentary series of protrusions of the Russian Plate, structural formations that correspond to the terrain of the continental crust take part. They are the most characteristic for the Ural orogenic belt, which belongs to the group of epiokean-type belts, associated with the transformation of ocean basins with the active participation of accretion and collision processes. The parametric features of these terrains include the ancient age characteristics of terrain rocks, their position in the belt structure, as well as the presence of relics of subhorizontal layered structural elements. The discordant blocks of migmatites, gneisses and other metamorphic rocks of Precambrian age, which make up the terrains, was the basis for the introduction of the term “terranes of the ancient continental crust”. By connection with the source, exotic and endemic, and simple and complex terrains are distinguished by structure. The geodynamics of including terrains of the ancient continental crust into the structure of orogenic belts is associated with horizontal movements of fragments of the ancient lithosphere in oceanic paleobasins to the periphery of the Russian Plate and their localization in belt structures. The formation of these terrains in the structures of the orogenic belts is completed by the formation of the intra-terrain massifs of granitoids and belts of volcanic-intrusive series. Supporters of a different methodology, dominant among researchers of the Pacific Belt of the Northeast Segment of Eurasia, refer to terrains all the structural elements that perform orogenic belts, because they believe that they have undergone horizontal movements and are in allochtonous occurrence. Conclusions. It has been established that in different geological provinces the term terrain has its own characteristics. This was the basis for the selection of two geodynamic types of terrains.

Subject of the study.We have carried out an additional exploration on petrography, petrochemistry, geochemistry, geochronology and biostratigraphy of rock complexes of the Yugansk-Koltogorsk (central part of West Siberia).Materials and methods.The materials are core samples from wells that penetrated the Pre-Jurassic basement rock complexes The used methods are as follows: X-ray spectrum microanalysis (Cameca SX 100, JEOL-733 Superprobe); the silicate analysis of the rocks (СРМ-18 and EDX-100); mass-spectroscopy with inductively coupled plasma (ICP-MS) (ELAN-9000 and Element2); zircons were analysed with a high resolution ionic microprobe SHRIMP-II (U-Pb); Ar-Ar dating was carried out by Micromass 5400; biostratigraphy, petrochemestry.Results.A geological map of Yugan-Koltogor zone of the central part of West-Siberian plate in a scale 1:500 000 was created. The map is a set of informational geological, geophysical and other layers. It was established that age of granites is Early Permian, the basalts of the rift zone began to form 268.4 ± 7.5 Ma ago (Ar-Ar). Conclusions. Volcanism in the axial rift zones of the West-Siberian megabasin basement began earlier than it is supposed before our study and significantly earlier of that of trap basalts of Siberian platform.

- . . . , . . . I () . Neostreptognathodus ruzhencevi Kozur N. peuopen . peuopen peuopen-

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.

In the present paper by the authors materials are given the investigation results of different types quartz vein from endogenous quartz-vein formations of the Urals. In the course of accumulation of the materials on different types of quartz researches it occurred an opportunity of interpretation the obtained data for deciphering of quartz-vein formation genesis, since the contents of structural impurities in quartz objectively reflect its genesis particularities and can be used as a criteria for forecasting and estimating of objects both of ore and nonmetalliferous mineral products. Analysis of materials quartz-metric survey showed that quartz-vein objects have a polygenic and polychronic genesis and are localized in different structural-formation zones. This makes it possible to more purposefully carry out the forecasting of large objects of extremely pure quartz.

The object of study is clastic Middle Triassic of the central part of the Pronchishchev Range. The territory of researches is located on the border of Ust’-Anabar and Lena-Olenek facies districts and has poor geological knowledge. During field study of outcrops and test pits new data for Triassic of the right bank of the Peschanaya River were obtained. Lithofacial analysis and analysis of cyclical structure of the Anisian and Ladinian were carried out. The stratigraphic subdivision of the strata was made according to the results of a comprehensive bio- and lithostratigraphic analysis. The succession includes the Karangatinskaya and the Tuora-Khainskaya (Anisian), the Ust’-Olenekskaya and Olimpiiskaya (Ladinian) formations. The lithofacial analysis showed that the sedimentation occurred in mainly sea-shallow conditions with constant exposure of normal waves. Upward the succession a part of coastal sediments increase. Stages of fast sea level rising took place. The analysis of cyclical structures showed that the studied deposits represent the series of regressive sedimentological cycles of decameter scale with а transgressive orientation. They form the large regressive sedimentary cycle with a pronounced binomial structure. It has been found that the Anisian part of the studied section has very similar features of a structure with Leno-Olenek type sections. The structure of the Ladinian part is also similar to the sections of the Lena-Olenek type and is characterized by a slightly reduced thickness of the Olympic formation. It is typical for the western part of the Lena-Olenek facies district. Structural features of the selected cycles allow you to use them in lithostratigraphic correlations of geological sections within the considered sedimentation basin. This is especially true for sites with rare and relatively uniform fossil fauna.

The microbial structures of various genesis are rock-forming components in limestones of the Kizelovian regional substage (the Tournaisian stage) on the Middle Urals eastern slope. Comprehensive petrographic analysis of distinct grains allowed to reconstruct the carbonate platform depositional environments. Microbial structures in this study include: 1) calcitarcha (calcite “spheres” and similar sub-circular microfossils), 2) bioclasts of calcareous green algae, 3) bioclasts of calcified cyanobacteria/calcimicrobes (or calcibionts), 4) most peloids and traces of grains micritization, 5) oncolites (oncoids) and intraclasts of other microbialites. Environmental indicators evidence that sedimentation throughout the Kizelovian time was carried out within the upper subtidal photic zone, in conditions of high salinity and limited water circulation. A distribution of microfacies shows that the basin depth at an average corresponded to the normal wave basis. Microbiota taxonomic composition and bottom configuration features largely determined differences in sediment deposition characteristics. Some carbonate sedimentology terminologic issues are also discussed in this article.