Research subject. Research articles and notes published during the period from 2010 to October 2024 and available at the Scientific Electronic Library on the eLibrary.ru platform on the minerageny and mineralization of Riphean rocks in the Bashkir meganticlinorium, one of the largest structures on the western slope of the Southern Urals. The Riphean sections of the western wing of this structure are the stratotype for the Riphean group. Materials and methods. New findings, ideas, and hypotheses on the mineralization and minerageny of the Riphean obtained as a result of long-term work by authors from different regions of Russia were analyzed. Results . The conducted review of various minerageny and mineralization aspects of sedimentary and igneous rocks of the Riphean Bashkir Meganticlinorium showed that over the past 10–15 years, a large number of works have addressed both specific and fundamental issues. As a result, based on a large variety of data (from geological data to isotope-geochemical data), the formation models of large deposits have been proposed. Among the latter are magnesites, siderites, fluorites, Fe–V–Ti ores in differentiated gabbro massifs, etc. Conclusions. The presented analysis provides the reader with a comprehensive overview of contemporary research on diverse types of mineralization in igneous and sedimentary rocks. These include Au, PGE, Au–Pt, Pd–Au–rare-metal assemblages; U- and Th-bearing minerals; complex REE phases; native Ag and its compounds (including furutobeite and Au–Ag sulfoselenoarsenides); as well as Mo-bearing galena and pyrrhotite enriched in Au, Se, and Mo. The review also highlights large and unique deposits hosted within the sedimentary sequences of the Riphean Bashkir meganticlinorium. Many of the studies considered have been conducted to highest academic standards.
Research subject . Structural and tectonic provinces represented by multiple alternations of negative (depressions, grabens, graben-synclines) and complementary positive (uplifts, horsts, horst-anticlines) morphostructures, known as areas of diffuse (dispersed, areal) rifting. The following geological objects are analyzed: the Province of Basins and Ranges (North America), the Selengino-Vitim Zone (Western Transbaikalia), the Sunda Shelf of the South China Sea, the Gissar-Alai and Central Segments of the Tien Shan Alpine Orogen. Aim . To characterize the structure, formation mechanism, and geodynamics of “areal” rift systems, as well as to determine their place in the structure and evolution of the Earth’s crust. Methods . Comparative structural and tectonic analysis of geological objects using remote and experimental research data. Results . The main characteristic features of the structure and evolution of areal (diffuse) rift systems have been established. These include the multiple alternation of troughs (grabens) and uplifts separating them (ridges, mounds, shafts); the spread of the “depression/uplift” paragenesis in the form of wide areas confined to the marginal parts of young and ancient platforms or to intracontinental orogens; the absence of main rift valleys and faults; absence of through-core faults; connection with volumetric loosening and solid-plastic (rheid) flow of basement rock masses within dynamically weakened areas of the Earth’s crust and shear stress field with the regulating role of fractal organization of geological space. Conclusions . The provinces under consideration are paragenetic ensembles of 3D shear and can be morphostructurally defined as “basin and ridge provinces”. Tectonic ensembles of this type are a specific category that is neither structurally nor dynamically analogous to linear rift systems. Linear rift systems are derived from the mechanical splitting and spreading of continental crustal segments (a component of subglobal tectogenesis), while areal systems are the result of brittle–plastic (reid) flow of rock masses within dynamically unstable areas of platforms and orogens (a component of regional tectogenesis).
Research subject . The igneous rocks examined in this study were collected from outcrops located in the vicinity of Sergeevka and Vladimiro-Alexandrovskoye (Okrainsko-Sergeevsky terrane), as well as Kamenka (Kamensky allochthon), villages. The studied jaspers, manganese silicate rocks, and silicate-magnetite ores were sampled from outcrops within the Olginsky and Dalnegorsky ore regions (Taukha terrane) and the Malinovsky ore region (Samarka terrane). Aim. To clarify the geological events in the evolution of the Sikhote-Alin region that determined changes in the geochemical parameters of the Cambrian (?) basites of the Sergeevsky complex. To that end, the petrography, petrochemistry, and geochemistry of the metabasites of the Sergeevsky complex and metamorphosed Triassic metalliferous sediments were studied. Methods . Gravimetry, inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS) were employed, the latter for the determination of trace and rare elements. The isotopic compositions of Nd, Pb, and Sr were also analyzed. Mineral identification was performed using optical microscopy and subsequently confirmed by compositional analysis with an X-ray spectral microanalyzer (JXA-8100). Results . Analytical data were obtained for metabasites and metaultrabasites of the Sergeevsky complex, including major and trace element compositions and Nd, Sr, and Pb isotopic ratios; their mineralogy and internal structures were also investigated. In addition, analytical data were acquired for jaspers (major and trace elements), as well as for manganese– silicate and silicate–magnetite rocks and ores (trace elements and Nd isotopic ratios) of the Triassic chert formation of the Sikhote-Alin. Conclusion . The obtained data indicate that metamorphic processes significantly influenced the geochemical characteristics of the metabasites. The integrated application of igneous and sedimentary geochemistry, in combination with chemostratigraphic analysis, made it possible to elucidate the systematic variation in paired parameters (¹⁴³Nd/¹⁴⁴Nd– Sm/Nd, ¹⁴³Nd/¹⁴⁴Nd–Y/Nb, and ¹⁴³Nd/¹⁴⁴Nd–Zr/Y) in the metabasites of the Sergeevsky complex, trending toward values characteristic of metalliferous sediments of the Triassic chert formation of Sikhote-Alin. This trend is interpreted as evidence for seawater involvement in metamorphic processes. The involvement of seawater, supported by Sr isotopic ratios in the altered rocks and regional geological data, suggests that diaphthoresis of the Sergeevsky basites occurred during Middle–Late Jurassic accretion.
Research subject . The issues related to the task of correlating the boundaries of Phanerozoic stratigraphic units are discussed. The concepts of chronology, chronometry, zone, zonal method, stratigraphic boundary, marking of stratigraphic boundaries, establishing the chronological identity of stratigraphic boundaries are defined. Material and methods . Criteria for the reliable correlation of stratigraphic boundary division in remote-region sections are specified. Results. The boundary of adjacent stratigraphic divisions established using the zonal biochronological scale is a certain zone. This boundary is the corresponding (eponymous) stratozone in the section. The linear nature of the boundaries of geological objects, determined using the chronological scale, is recorded only on the zonal scale. Real (natural, material) boundaries of geological objects in the section are always volumetric. Conclusions . For the accurate comparison of stratigraphic boundaries, an elementary zonal biochronological scale comprising three zones is required. This scale serves as the primary tool for the identification and correlation of stratigraphic boundaries across all hierarchical levels of the Phanerozoic stratigraphic system. Boundaries of stratigraphic units located in distant sections are considered coeval (chronologically equivalent) provided that they occur within a specific, eponymous stratozone defined using a standard zonal biochronological scale for the corresponding stratigraphic interval.
Research subject. Barremian-Aptian palynomorph assemblage of terrestrial and lacustrine genesis in the Belaya Gora (Semyon) section, Transbaikalia, Chita region. Aim. Based on integrated approach to palynomorph study, to determine the age of the sediments as well as the specific features of paleoflora and its relationship with climatic conditions, paleolandscape and transgressive-regressive fluctuations in the paleolake. Materials and Methods. Samples were processed by a standard technique using heavy cadmium liquid, hydrochloric and hydrofluoric acids. Results . Diverse assemblage of spores and pollen of terrestrial plants of the Turga type is defined, which is strongly dominated by gymnosperms and contains rare angiosperms that is consistent with data from other biofossils. Abundant microphytoplankton of lacustrine genesis is also present. The stages of low and high stands in the lake are determined based on quantitative dynamics of spores, pollen and microphytoplankton. Conclusion . Biofacies analysis of palynological material shows that the sediments were formed in shallow slow-flowing mesotrophic lake surrounded by rich forest vegetation with highly diverse conifers, which is typical for warm and humid climate. Specific features of terrestrial paleoflora and mesotrophic type of the Belogorskoye lake suggest an elevated, but not sharp relief on the surrounding areas. Biostratigraphic range of the section is defined as the Upper Barremian - Lower Aptian. Literature data show that the Barremian-Aptian palynological assemblages of the Turga type are well defined in central regions of Transbaikalia as well as in Mongolia and China.
