Presents the results of magnetotelluric soundings acquired in 2020 along the profile Rzhev– Velikie Luki, in the suture zone of three parts of Precambrian crust of East European platform: Fennoscandia, Sarmatia and Volga–Ural. In the central part of the profile, anomaly zone of increased conductivity in the crust was revealed. The crust conductor is weakly expressed on the components of the telluric tensor due to the screening effect of the conductive sedimentary cover; therefore, the focus in the qualitative analysis of data and inversion was made on magnetovariational parameters.
According to the results of two–dimensional inversion carried out in the program of A.E. Kaminsky ZONDMT2D, on the geoelectric model a subvertical zone of low resistivity in the crust is identified, which is probably associated with the paleosubduction zone of the Belarusian Ocean Plate.
The results of the analysis of core and logs of the upper vendian sediments (vilyuchansky, nepsky, tirsky and danilovsky horizons) of the northeast of the Nepa-Botuoba anteclise are presented. Regional sequence-stratigraphic analysis made it possible to identify six third-order sequences and stratigraphic unconformities confined to their boundaries. The systemic tracts are represented by proluvial, alluvial, lagoon and shallow-water-marine sediments, successively replacing each other, which is typical for the passive continental margin and the general subsidence of the Siberian platform in the vendian time.
The results of a geochemical study and paleogeographic, paleoclimatic interpretation for a cyclically constructed section of upper Cretaceous deposits near Volsk city, Saratov region, are presented. Elementary formation cyclites and cyclic variations of a number of certain parameters were associated with the Milankovich astronomical-climatic cycles. The curves of changes of paleotemperature, humidity, paleobathymetry were compiled. The results obtained give an idea of the migration of the arid belt boundaries in the upper Cretaceous and the overall climatic zonation, which is important for regional and global paleoclimatic reconstructions, as well as the history of the development of shelf seas that covered the Russian plate (especially Ulyanovsk-Saratov trough). Paleotemperatures of the land surface in the denudation areas are obtained from the chemical index of alteration (CIA). In the Turonian-Campanian interval selected climatic cyclicity, including period of relative cooling (Turonian–Coniacian) with paleotemperature about 20 °С, the period of relative warming in the mid-late Campanian (20–24 °С), the cooling time at the end of the late Campanian (19–21 °С) and the period of warming at the turn of the Campanian and Maastrichtian and in the early Maastrichtian time. In Maastrichtian age, there are two climatic cycles, beginning with a time of relative cooling (about 19 °С) and ending with a time of relative warming (about 20 С, at the end of Maastrichtian to 25 °С). The cycles of climate humidity change are also determined: two cycles in Campanian time, three cycles in early Maastrichtian, and one cycle in late Maastrichtian. The boundary of the early and late Maastrichtian corresponds to the change of arid conditions to humid ones. The paleobatimetry curves show transgressive-regressive cycles: one in the late Turonian-Coniacian time, two in the late Campanian time, five in the early Maastrichtian time, and one in the late Maastrichtian time. Depth variations were estimated: in the Turonian-Coniacian time in the range of 70–80 m, in the Campanian-Maastrichtian time, the paleobatimetry consistently increased and changed from 100 to 200 m (on average about 150 m). The results obtaired give and idea of the migration of the boundaries of the arid belt in the Late Creataceous and main features of the climatic zonation, which is important for regional and global paleoclimatic reconstructions, as well as for the history of the development the Russian plate in the Ulyanovsk-Saratov region.
An integrated geophysical and mathematical model of the Norilsk metallogenic region has been built according to the authors’ method of automatic express interpretation of areal geophysical data. It consists of fifteen levels of hierarchy. The model is based on the use of the mathematical apparatus of fuzzy logic — artificial neural networks without a teacher using the method of self-organizing Kohonen maps. Formation of cluster groups is justified. Clusters characterize to the greatest extent possible connections between multidimensional geophysical data. The presence of relationships between them is analyzed by identifying correlation dependences. Analysis of various geophysical transformants using self-organizing Kohonen maps is carried out. A number of input indicators-representatives of their groups are determined, on the basis of which a geophysical-mathematical model is built. A model in the form of a two-dimensional map of clusters using fuzzy logic tools. Terminological sets were formed for each group of clusters. The form of membership functions of previously unknown geological objects is given according to new interpreted data. The calculated clusters according to the results of the study reflect the northwestern fragment of the basaltic magmatism fields of the trap formation, within which two ring structures have been distinguished. In the western part of the study area, the model ring structure reflects the Bolgokhtokhsky stock of granodiorites. The second, the Pyasinskaya ring structure, previously unknown, indicates the presence of a dome-shaped object at a great depth — a possible source of root zones of intrusions of the Norilsk complex. The conducted experimental study confirmed the adequacy of the constructed model and the effectiveness of its use for the purpose of express analysis of geophysical data and decision-making in geological prospecting tasks.
The paper is devoted to new finds of the Middle Permian fossil plants, which are kept at the Earth Science Museum of the Lomonosov Moscow State University. The palaeobotanical collections of the museum became significantly enriched by the adding of these new specimens. Some attractive specimens having high scientific potentiality (for instance, equisetophytes Annulina neuburgiana (Radczenko) Neuburg and leptosporangiate ferns Pecopteris anthriscifolia (Goeppert) Zalessky) will be used as materials for exhibitions, and will be involved into educational projects of the museum. Discovery of the leaves of cycadophyte affinity allows to develop the idea on possible migration of the termophylic tropical elements into boreal vegetation of the Angara type.
The quantity of the mineral composition of ore and parent rocks was carried out. Ore sections from the core samples of two wells of the Talnakh field were used for these studying. Also a number of their physical, mechanical, magnetic and electrical properties were determined. The content of the main ore minerals and useful components in the studied samples were calculated due to comparison of these data of their petrophysical properties. Additionally petrophysical anomalies in the external contact of ore horizons were identified. Using of this methodology may contribute to improving the efficiency of survey and evaluation work on Norilsk type sulfide mineralization.
Made an attempt of reconstruction structure of the Monchegorsk layered intrusion, assessing the composition of the original magma and the conditions of its kristallization. The problem was solved by simply comparing the structure of the Monchegorsk Intrusive with a similar analog (for this purpose, the Kivakka layered Intrusive was chosen), as well as using model constructions using the COMAGMAT software package.
Vysotskite is developed in Co-Ni-Cu sulphide massive and disseminated (“amygdaloid”) ores of the Norilsk-I deposit, entrained by post-trap low-grade metamorphism in the conditions of prehnite-pumpellyite and zeolite (lomontite) facies. Vysotskite associates with ferrian chlorite, cummingtonite, grünerite, prehnite, corrensite, ilvaite, babingtonite, pumpellyite, grinalite, millerite NiS, polydymite Ni3S4, galenite and chalcopyrite. This facies of metamorphosed sulphide ores were formed in the conditions of low oxidative potential and relatively high sulphide sulfur fugacity. This vysotskite is extremely poor in platinum, enriched in nickel and partly in iron. The average composition of studied vysotskite is (wt%, n=17): Pd 65,65; Pt 0,12; Rh, Au traces; Ni 8,25; Fe 0,95; Cu 0,32; Co 0,03; S 25,03; As 0,03; sum 100,38; the formula of the mineral is (Pd0,79Ni0,18Fe0,02Cu0,01)1S1. According to mineral associations and chemical composition, the described vysotskite corresponds to vysotskite discovered by A.D. Genkin and O.E. Zvyagintsev [1962]. Therefore, vysotskite holotype is metamorphogenic-hydrothermal vysotskite of the Norilsk-I deposit with (Pd,Ni)S composition.
This article displays data on cristobalite and tridymite from the Arsenatnaya active fumarole, the Tolbachik volcano, Kamchatka, Russia. The minerals occur in associations with fumarolic sylvite, sanidine, cassiterite, hematite, pseudobrookite, johillerite, tilasite, badalovite. Fumarolic cristobalite is tetragonal (-modification); the unit-cell parameters for one of samples are: а = 4,975 (7) Å, с = 6,944 (13) Å, V = 171,89 Å3. There are two types of tridymite — monoclinic (MC) and orthorhombic (PO-10) — in the Arsenatnaya fumarole. The unit-cell parameters of these tridymite modifications are: a = 18,553 (5), b = 5,006 (1), с = 25,952 (10) Å, = 117,68 (2)o, V = 2134,3 (11) Å3 (MC); a = 9,941 (2), b = 17,165 (4), с = 82,362 (18) Å, V = 14053,4 (29) Å3 (PO-10). Mineral assemblages of cristobalite and tridymite indicate high-temperature formation conditions of these minerals — not lower 450–500 °С — with a high participation degree of HCl and HF in process of basalt alteration by fumarolic gas. The surrounding basalt was a source of silicon. This element was, probably, transported in the form of SiX4, where X = F, Cl.
In the work the speciation of metals in the water and bottom sediments of the Malaya Senga River, located in the Petushinsky district of the Vladimir region were studied. It is shown that all studied metals in the waters are predominantly in a dissolved form. At the same time, most of Fe, Cu, Cd and Pb in river waters are in the form of complexes with organic substances (which are mainly represented by their negatively charged compounds), and the main forms of occurrence of Ni and Zn are inorganic compounds and cationic complexes with low molecular weight organic ligands.
In bottom sediments for the metals, the share of migratory forms of metals relative to the total contents is from 10 to 30%, while a significant part of them is represented by forms associated with iron and manganese hydroxides.
Frost heave and factors which affect it are considered on the projected railway Moscow– Kazan. That region is intensively developed; however, frost heave hasn’t been well studied in there, especially at the present climatic conditions. Results of field studies of frost heave properties of grounds on monitoring sites along the railway Moscow–Kazan are presented; they include physical properties of grounds, depth of seasonal freezing, grounds thermal mode, groundwater dynamics, snow cover thickness and basic characteristics of frost heave.
