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We present data on the geochronology, geochemistry, and Nd isotope composition of granitoids of the Gremyachikha and North Gremyachikha massifs (Kundusyul pluton) located in the Neoproterozoic metamorphosed island arc calc-alkalic volcanic rocks of the Talanovka-Bogorodka block in northern Kuznetsk Alatau (Martaiga uplift). The granitoids formed 890-880 Ma as a result of the accretion and collision of Neoproterozoic oceanic/island arc complexes with an unknown block formed by continent-marginal metasedimentary strata. The predominance of a metasedimentary source formed during the erosion of the early Precambrian and Neoproterozoic complexes is confirmed by the wide range of the ages of xenogenic zircons in the granitoids (2800 to 930 Ma) and by variations in the ε_Nd values (-7.8 to -1.0) and model Nd age of the granites (2.20-1.64 Ga).

We present the U-Pb (secondary-ion mass spectrometry, SHRIMP-RG) zircon ages and geochemical characteristics of granitoids penetrated by two boreholes at a depth of about 4.5 km in the Bolshezemel zone-the northeasternmost block of the Pechora Basin basement. The age of zircon from granites from the 26-East Khar’yaga borehole is 558 ± 6 Ma. These granites are similar in composition and age to syncollisional granites of the Charkayu granite-granodiorite complex of the Pripechora fault (suture) zone (555-544 Ma). Dating of zircon from granodiorite from the 2-Veyak borehole yielded an age of 607 ± 6 Ma. Potassium-rich granodiorites and granosyenites from this borehole have geochemical features of within-plate granites and are correlated with granites (602-595 Ma) of the southeastern part of the Izhma crustal block of the basement, which is supposed to be a submerged part of the northeastern passive margin of the Baltica paleocontinent.

The Mokrundya alluvial gold placer deposit is located in the Verkhoyansk-Kolyma folded region, within the Tuguchak ore-placer cluster. Using ore and scanning electron microscopy and chemical-analysis methods, we have studied the typomorphic, mineralogical, and geochemical features of gold, minerals of the heavy fraction of the placer, and ore mineralization of the dolerite dike complex stripped in the placer bedrock. The stages of development of the ore-forming system in dolerites have been established. The main productive stages with native gold are associated with the postmagmatic stage: (1) early arsenopyrite-polysulfide stage and (2) gold-bismuth-telluride stage. The gold-bismuth-telluride stage includes bismuth tellurides and sulfotellurides, native gold, bismuth, maldonite AuBi₂, and complex intermetallic compounds of Au and Bi. We hypothesize about the sources of placer gold in alluvial deposits, one of which is the ore mineralization of the dolerite dike complex, and the other is associated with the mineralized zones of the Gematitovoe skarn-hydrothermal ore occurrence localized in the upper reaches of the Mokrundya Brook.

The paper presents data on the classification, structure, and biota of reef complexes from the Late Ordovician--early Silurian Altai Basin. The early Paleozoic history of the Altai Basin included the early--middle Katian, late Katian, early Hirnantian, late Telychian, and middle--late Sheinwoodian events of large-scale reef formation which produced framework reefs, mud mounds, and coral meadows. The early Paleozoic reefs of the area formed at rates of 40 to ~12 cm per thousand years. The late Telychian reef system, which formed in 0.5-1.0 Myr, occupied the largest area of the basin. The lateral extent of reef systems in the Late Ordovician-early Silurian basin of Altai depended more on the rates of vertical and lateral growth, as well as on the previous sea bottom topography and clastic inputs, than on the duration of reef formation. Carbonate deposition in the Altai basins of that time can be simulated with a general model implying formation of distal barrier reefs.

The study area is located within the Chernyshev Ridge, a fold-thrust structure, which is a promising area for oil and gas exploration in the Timan-Pechora province. Petroleum source rocks of Paleozoic (from Upper Ordovician to Lower Carboniferous) deposits stripped by the Vorgamusyur-1 well in the Talbei block of the Chernyshev Ridge were studied by lithological, petrographic, organic-petrology, and organic-geochemistry methods. Most of the section is characterized by low values of C_org (<0.5%), genetic potential (S₁ + S₂ < 0.5 mg HC/g rock), and hydrogen index (HI < 100 mg HC/g C_org). Petroleum source rocks with elevated values of C_org (up to 0.9%), S₁ + S₂ (up to 2.1 mg HC/g rock), and HI (up to 277 mg HC/g C_org) were identified at different stratigraphic levels of the section: Upper Devonian (D₃tm-sr), Upper Silurian (S₂gj), and Upper Ordovician (O₃mt). The maceral composition of organic matter (OM) and the distribution of hydrocarbons in the saturated fraction of bitumens indicate that petroleum source rocks include only marine OM (type II kerogen). The catagenetic transformation of OM was assessed based on the bituminite reflection (RV_eq), Rock-Eval pyrolysis temperature (T_max), and conodont color alteration index (CAI). The available RV_eq (0.63-0.84%), T_max (430-443 °C), and CAI (1.5-2.0) data indicate that the entire Paleozoic well section is in the oil window (MC₁-MC₃). The new data refined the catagenetic zonality of the sedimentary section, according to which the OM reached the following gradations: MC₁ in the lower Carboniferous and Famennian deposits, MC₂ in the interval from the Frasnian to the upper part of the Lower Silurian, and MC₃ in the Lower part of the lower Silurian and in the Upper Ordovician. The results of a study of petroleum source rocks and the type and maturity of OM will be the basis for basin modeling, which will increase the reliability of reconstructions of oil and gas formation at the Chernyshev Ridge.

Based on new data on the geology, composition, U-Pb isotopic age, and paleomagnetism of the metavolcanic rocks of the Kataevo Formation, we consider the geodynamic conditions of their formation and alteration. The Kataevo Formation metavolcanic rocks belong to the K-Na-high-alumina andesite-andesibasalt-basalt volcanic series. Results for U-Pb analysis of magmatic zircon (SHRIMP II, 8 spots) from a metaandesibasalt sample of the stratotype section on Ungo R. yielded and age of 852 ± 9 Ma. Isotope systems for Sm-Nd yield a positive ε_Nd(852) = + 9.29, which indicates a juvenile magmatic source, close to depleted mantle (DM), with a Neoproterozoic protolith T_Nd(DM) model age. The content of the less mobile HFSE and REE (ppm) is consistently low for Nb (8-15), Ti (7074-12,410), Ta (0.32-0.93), Eu (1.80-2.29), Се (50-79), Y (21-25), Yb (2.1-2.8), Rb (10-24) and elevated for Sr (1000-1500), Zr (170-270), La (25-41), and Ba (600-800). All studied parameters place the metavolcanic rocks close to the contemporary Kurile-Kamchatka type of developed island arcs. Paleomagnetic analysis of the section of metavolcanic rocks shows a complete remagnetization ca . 120 Ma. This is synchronous with manifestations of intraplate basaltoid magmatism in the studied region, the most typical example of which is the Lower Cretaceous Khilok Formation.

We present the first results of a comprehensive isotope-geochemical study of dolomitic carbonatites of the Mal’dzhangarka massif located in the southeast of the Billyakh melange zone (southeastern periphery of the Anabar Shield). Zircon grains separated from core samples from a depth of 6-30 m have a three-phase structure. All of them were trapped from the host metamorphic rocks and mark the age of the main stage of high-gradient metamorphism in the region, 2027 ± 9 Ma. Pyrochlore containing 38-705 ppm U and 5-21 ppm radiogenic Pb, with weak metamictization of the crystal lattice and an undisturbed U-Pb system, made it possible to estimate the concordant age of rare-metal mineralization in the massif, 167 ± 4 Ma, which is probably close to the crystallization age of the host carbonatites. The estimated age corresponds to one of the stages of kimberlite-carbonatite magmatism on the eastern slope of the Anabar dome. The Rh-Os isotope system of pyrite from superposed late carbonate-sulfide veinlets in the carbonatites testifies to a close (within the error of determination) age, 179 ± 14 Ma, and a low initial Os isotope ratio, which indicates the contribution of mantle material to the formation of this isotope system.

The paper discusses current state of the spectral approach to analysis of induced polarization (IP), its possibilities and limitations, along with directions for the method development. Reviewed are the main methods and approaches for estimation of spectral IP parameters and their specific features. Our practical experiments have shown the advantages of analysis of transient IP characteristics over standard approaches to the IP data analysis and processing. Results of the standard and spectral approaches application to analysis of IP data when solving mineral exploration problems at the Maletoyvayam gold deposit (Kamchatka Peninsula) and the Yasnoe gold occurrence (Taimyr Peninsula) are compared. Here, we demonstrate that low efficiency of works is erroneously regarded as one of the main factors hindering a broad adoption of the spectral IP method in mineral exploration activities. Rather, it is a lack of automated techniques for analysis of transient IP characteristics. We propose a new approach to spectral analysis of IP data, based on the algorithms for image recognition of a reference object, and describe pioneering efforts of its practical application.

Possibilities to construct the sections of thermal conductivity, specific heat capacity, as well as heat flow density at the surface, using electromagnetic sounding data and laboratory measurements on core samples, have been studied. It has been shown that neural network prediction of thermophysical properties from electromagnetic sounding data and laboratory measurements enables estimating these properties not only below boreholes but also in the interwell space, with relative accuracy around 6-10 %. Sections of «dry» and «warm» thermal conductivity, specific heat capacity and a profile of the heat flow density at the surface of the study area, along magnetotelluric sounding profile, have been built.

The study addresses basic problems of modern geodynamics and seismicity of the Central Asian lithosphere. It aims at predicting dynamic effects of large earthquakes for seismic safety of the Baikal-Mongolian region. Special focus is made on the seismic behavior of areas where seismic risk zoning is problematic because of permafrost. The paper presents synthesis of previous and new data on ground responses to large earthquakes in specific territories of the Baikal-Mongolia region with complex cryological conditions. The results include shaking intensity patterns and predicted seismic parameter values for degraded permafrost in zones of different climates and seismicity levels. The obtained prediction maps can make reference in studies of variable permafrost responses to temperature, seismic, and mining-related impacts.