Abstract New data on the 87Sr/86Sr ratio variations in carbonate rocks of the Dal’nyaya Taiga Group in the Vendian reference section (Ura Uplift, Central Siberia) are presented. The 87Sr/86Sr variations correlate with the sequence-stratigraphic scheme reflecting evolution of the paleobasin, δ13C variations, and paleontological data. Limestones with a high (>1050 µg/g) Sr concentration, which do not

Abstract The Briketno-Zheltukhinskoe U–Mo–Re deposit is located in the southern sector of the Moscow lignite basin (central East European Platform). It is restricted to the paleochannel and deltaic coal-bearing sandy sediments of the Visean Bobrikov horizon lying on the Famennian limestone. They are overlain by the younger Neogene–Quaternary sands and clays. Tectonically, the deposit is ascribed to

Abstract A complex of lithological-geochemical studies was carried out in rocks of the Upper Jurassic–Lower Cretaceous Bazhenov Formation and their transition zones to host rocks: composition of rocks, ratio of organic carbon and sulfide sulfur (C/S values), and distribution of several redox indicators (degree of pyritization, content of the authigenic uranium, and values of Mn/Al and Mo/Mn ratios)

Abstract The article presents data on numerous findings of authigenic K-feldspars in the Lower–Upper Carboniferous carbonate and terrigenous rocks in the southern limb of the Moscow syneclise, including the Oka–Tsna bar. In terms of the composition and crystalline structure, all feldspar morphotypes (idiomorphic monocrystalline fringes on the surface of sandy clastic grains, fine-crystalline aggregates

Abstract Morphology of the Rio Grande Rise and the acoustic structure of different types of deposits in its uppermost sedimentary cover were discussed based on high-resolution seismoacoustic profiling of cruises #32 (2010) and #52 (2016) of R/V Akademik Ioffe. Slopes of the Rio Grande Rise are composed mainly of landslide deposits and gravitites, but contourite sedimentation is possible on its southern

Abstract The Haléo-Danielle Plateau bauxite deposit forms the largest part of the 15 km long Minim-Martap Bauxite ore district in the Adamawa Region of Cameroon. The plateau is covered with thin Upper Pleistocene to Holocene alluvial layer. It covers by laterites and bauxites formed on Tertiary-Quaternary basalts. Gibbsite and boehmite are the aluminum oxide found in the bauxite, while goethite is

Abstract In 13 out of 14 samples of carbonate xenoliths from mud volcanic breccias of Azerbaijan, the 87Sr/86Sr values (0.70675–0.70823, 87Sr/86Srmd = 0.7073 ± 0.0005) are within the same limits as in the volcanic waters (Bujakaite et al., 2019). Genetically, they can be associated both with Mesozoic carbonate and saline deposits or with Cenozoic volcanosedimentary strata. Similarity of the Sr isotopic

Abstract The coastal-marine rare metal–titanium placers of the West Siberian megaprovince were formed in a relatively short Eocene–Late Oligocene interval. A similar formation mechanism and commonality of primary sources of ore matter were responsible for the single type and similarity of mineral composition of placers in the megaprovince. Based on the comparison of various characteristics of these

Abstract The results of lithological, petrographic, and C–O isotope studies of various types of the diagenetic and postdiagenetic carbonate cement in silty mudstones, as well as coeval limestones, in postglacial deposits of the Dal’nyaya Taiga Group (Patom Basin, Siberia) are presented. Evidence of methane generation but not its anaerobic oxidation has been obtained. High δ13C (up to 14.9‰) values

Abstract The geothermal and hydrochemical parameters of a large hydrogeothermal system located in the city of Velingrad and its environs (southwestern Bulgaria) are discussed. The article summarizes the results of its research, including those obtained by 2019. Temperature of the discharging thermal waters varies from 37 to 94°C. The hotter mineral waters have SO4–HCO3/Na composition with pH ≈ 8.0

Abstract The study of structural features along with carbon and oxygen isotope compositions made it possible to discriminate lithological rocks in deposits of the Karatau phosphorite basin (Kazakhstan) into the following types: high- and low-grade phosphorites; unaltered and altered dolomites (with and without phosphate) hosting phosphorites of the Chulaktau Formation (lower dolomite and Fe–Mn horizons);

Abstract Distribution of carbonate sediments of different composition in the Precambrian section is reviewed. It is shown that calcium carbonates prevailed in the Archean–initial Early Proterozoic, and iron carbonates dominated in the banded iron formations. Dolomites and magnesites were more widespread in the Proterozoic. Such distribution suggests an acid reductive geochemical environment in the

Abstract Clay minerals in basalt sills from the northern East Pacific Rise, covered by Upper Pleistocene clayey–sandy–silty sediments (turbidites, hemipelagites, and diatom oozes) sampled from DSDP Holes 477, 478, and 481A, were studied by X-ray methods based on the modeling of diffraction patterns. Trioctahedral smectites formed in thin (0.1–0.5 and 1.8–4 m) fissured sills that are well permeable

Abstract The behavior of stable carbon and oxygen isotopes in carbonates during the deposition and diagenesis of sediments in the bioproductive Upper Famennian Pripyat Trough (southern Belarus) is discussed. Limestones and clayey limestones (Corg 0.92 ± 0.11%) are characterized by very low δ13C values (–9.6 ± 0.3‰). Parental sediments of these rocks were deposited in the shallow-water zone during slow

Abstract Data on the mineral and chemical composition of samples of sulfide deposits from the Broken Spur and TAG (Mid-Atlantic Ridge) are presented. The main minerals in the Broken Spur field are marcasite, pyrrhotite, pyrite, chalcopyrite, and sphalerite; in sample from TAG: chalcopyrite, pyrite, and marcasite. It has been established that these sulfide minerals of Fe, Cu, and Zn are natural ion

Abstract The article presents a brief lithological description of modern bottom sediments collected in the Barents Sea during Cruise 67 of the R/V Akademik Mstislav Keldysh at test sites: (1) “Pechora Sea”; (2) “Western slope of the Kanin Shoal”; (3) “Central Barents Sea (Shtokman area)”; (4) “Russkaya Gavan Fjord”; (5) “Medvezhinsky Trough”; (6) area south of Spitsbergen; (7) “Kola Meridian”; (8)

Abstract Data on the concentration of rare and rare-earth elements in the Devonian manganese-rich metasediments of the Polar Urals and Pai-Khoi Ridge are presented. It is shown that Sc, V, Rb, Zr, Nb, Hf, Th, and U represent elements delivered to the metalliferous sediments as a part of the detrital material. Excess (relative to the background detrital material) concentrations are established for Li

Abstract New data on the structure and formation conditions of the Anabar–Lena sedimentary basin in the Nordvik facies region at the beginning of the Early Jurassic (Hettangian–early Pliensbachian) are presented. Based on a detailed lithofacies analysis, coastal-continental, coastal-marine, and shallow-marine sedimentation conditions were reconstructed. Ichnofacies studies were carried out for the

Abstract The results of integrated study of the Cretaceous/Paleogene transition in the northeastern Caucasus are reported. The lithological, geochemical and micropaleontological characteristics of the sediments from two sections (Okhli and Gubden, Mountainous Dagestan) accumulated in different parts of paleobasin are displayed. An analysis of nannofossil distribution at the Cretaceous/Paleogene transition

Abstract Based on materials obtained during Cruise 37 of the R/V Professor Logatchev in the Russian exploration area, the species composition, distribution, and preservation of nanno- and microfossil carbonate shells in biogenic bottom sediments within the Pobeda hydrothermal cluster (17°07.45′–17°08.7′ N MAR) were studied. Physicochemical parameters and total carbonate content were measured and their

Abstract Now more than one century after the publication of works of V.I. Vernadsky and Ya.V. Samoilov, important role of the biogenic factor in the sedimentary ore genesis has become an undeniable fact for all geologists. Discussions at present are concerned mainly with creative nature of the activity of organisms in the formation of specified mineral resources. In the collective monograph of Russian

Abstract Manifestations of short-term global and subglobal events have been recognized in the Mesozoic and Cenozoic sedimentary record of the North Caucasus: Paleocene/Eocene boundary PETM, late Cenomanian (OAE2), late Albian (OAE1c and OAE1d), terminal Aptian–early Albian (OAE1b), early Aptian (OAE1a), late Hauterivian (Faraoni), late Valanginian (Weissert), early Toarcian, late Pliensbachian, and

Abstract The paper presents the geological setting, structure, lithology, and placer-controlling factors in the Krasnokutsk placer rare metal–titanium deposit located in Miocene sediments on the northeastern slope of the Dnieper-Donets Depression. The identified lithofacies (alluvial-deltaic, coastal- and shallow-marine, eolian) complexes correspond to the lower (Aquitanian), middle (Burdigalian),

Abstract Carbon and oxygen isotope compositions were determined in the pedogenic, sedimentary, and organogenic carbonates from Upper Permian (Vyatkian Stage) and Lower Triassic (Induan Stage) continental rocks in the northeastern Moscow Syneclise. Variations of δ18O (18.0 to 29.1‰ SMOW) and δ13C (‒8.8 to 0.7‰ PDB) in them could be provoked both by regional climatic fluctuations and by perturbation

Abstract Pyrite nodules were found in thin-layered sulfide ores localized at the flanks of the Talgan Cu-Zn massive sulfide deposit (South Urals) which consists of (1) an inner core (microgranular pyrite with inclusions of gangue minerals and authigenic sulfides), (2) an intermediate zone (anhedral and subhedral pyrite metacrystals), (3) an outer zone (parallel-columnar subhedral pyrite crystals),

Abstract The Sr isotope composition was studied in waters from 22 mud volcanoes in Azerbaijan, where the O and H isotope compositions, as well as concentrations of macro- and microelements, were determined earlier in (Lavrushin et al., 2015). Values of the 87Sr/86Sr ratio in the Azerbaijanian mud volcanoes range from 0.7067 to 0.7083. Its minimum value was recorded in water of Neftechala Yuzhnaya Volcano