A complex crystal-chemical analysis of 1567 oxygen positions in 216 crystal structures of lead- containing minerals belonging to the classes of silicates, phosphates, oxides, oxohalides, and a number of others has been carried out. It was shown that the combined application of the bond valence method and the analysis of the geometric characteristics of Voronoi-Dirichlet polyhedra make it possible to confidently distinguish between oxygen positions related to cation structure blocks and oxygen positions for which a description based on an anion-centered approach is more justified. Numerical indicators for such a separation of oxygen positions are substantiated, which can be used to analyze large arrays of structural data using the machine learning approaches.
The forms of salt uplifts are formed under the influence of stresses developing in the earth’s crust and, therefore, can be considered as sensitive indicators of the interaction of geodynamic systems. In the North German basin, in the Cis-Ural trough on the border with the Caspian depression and in the Pripyat trough, under the influ- ence of various sources of stress and deformation, forms of salt uplifts arose, reflecting the superposition of these systems. The mechanisms of such a superposition were both the formation of forms associated with the resulting addition of deformation vectors and the interference of forms associated with each geodynamic system separately.
The Turonian ammonite Kamerunoceras sp. ex gr. turoniense (d’Orb.) was found for the first time in the South-Western Crimea, in the section of the Aksu-Dere ravine, northward of the Kudrino Village (the Kacha River basin). This is the first discovery of representatives of this genus in Russia.
The Evenki Formation of the Siberian Platform is studied on the right bank of the Podkamennaya Tunguska River near the settlement of Sulomay (Evenki municipal district of Krasnoyarsk region). The structures and textures of composing sediments is described. The main petrogenic oxides are identified and the normative mineral composition is calculated following this identification. The increase of terrigenous components in the strata indicates periods of enhanced erosion in the provenance area, which is the Yenisei Ridge. In turn, the increased contribution of feldspars in the middle part of the section shows intensification of physical weathering in arid conditions. The principal hypotheses on the origin of the Evenki Formation as well as of other recent and ancient tidal flat and sabkha facies are outlined. We suggest that the facies of the Evenki Formation under study have been accumulated mostly under intertidal and, possibly in part, under lower supratidal conditions, which alternated depending on eustatic fluctuations in the basin. A conceptual model of the genesis of the Evenki Formation on the Siberian Platform is developed.
The appearance, composition, types and distribution of the first Devonian fossil forests on Earth, the finds of which are extremely rare, are considered. There are 5 known localities: three in the Middle Devonian (the Middle Eifelian locality Lindlar in Germany; two Upper Givetian localities Kairo and Gilboa in the USA) and two in the Upper Devonian (the Lower Frasnian locality Munindalen on Svalbard Norway and the Upper Famennian locality Xinhang in China). The terms fossil foresst, forests community and types of fossil forest, not mentioned by previous researchers, are highlighted, and a detailed plan for their description is proposed (formulations are given only for remains in the status in situ). The stratigraphic sequence of the first forests in the Eifelian Century — the Late Devonian epoch of the Earth’s history is presented, taking into account the recently published data. Two types of forests have been identified with the indication of the dominant genera in each: the cladoxylopsid type, common in the Middle Devonian and the lycopodiophyte type, characteristic of the Upper Devonian.
Comprehensive review of monographic paleontological collections from the Earth Science Museum at Moscow State University is undertaken. Systematic and number composition, territory of collecting and the age of enclosing deposits are analyzed. The importance of monographic collections as a fundamental element for the description of new taxa, stratigraphic constructions and correlation of deposits of the same age in remote areas is emphasized. Directions of research work with materials of the monographic collections are shown. Information on the form of accepting collections in Museum from authors is provided.
In the paper, the relationship between climatic changes and sedimentation conditions for 4 accumulation stages of the Fuxin and Shahai coal-bearing formations of the Fuxin coal basin in the Aptian-Albian time was established using mathematical statistical methods. As a result, it was observed that the increase in climate humidity coincided with the widespread anoxic oceanic Paquie event (Paquie, OAE1b) during the early Albian time. In addition, a significant influence of facies conditions on the intensity of peat and coal accumulation processes of the Fuxin and Shakhai coal-bearing formations was revealed.
The Bazhenov high-carbon formation is a part of the Bazhenov formation, characterized by a high content of aquagenic organic matter. Formation is a perspective source for expanding the hydrocarbon resource base. The article presents a combination of the results of core studies, interpretation of well logging and seismic data. A multi-faceted approach to the study of rocks made it possible to divide the West Siberian basin into 13 structur- al-facies zones, each of which has its own structural features of the bazhenov high-carbon formation section. This typification of the section will make it possible in the future to simplify the modeling of the properties of bazhenov high-carbon formation and predicting the most prospective areas.
This research identifies sedimentation settings of Lower Cretaceous (Aptian-Albian) terrigenous sediments of the North Caspian, which are oil and gas reservoirs. These rocks are characterized by irregular distri- bution of pelitic and silty fractions, which leads to ambiguous results of petrophysical analyses. In order to correctly interpret the geophysical data, a detailed lithologic analysis of the rocks was carried out. In the studied area in the Early Cretaceous time marine conditions prevailed: coastal, shallow-marine, relatively shallow shelf lithofacies with signs of active hydrodynamics, as well as relatively deep-water shelf lithofacies of low hydrodynamics. The study of sections reveals a change from shallow-water sediments to deeper-water sediments and vice versa, which allows us to conclude that the sea level fluctuates periodically. Lithologic analysis also showed the predominance of shallow-water and coastal sediments in the Aptian time and deeper-water, shelf sediments in the Albian time. Consequently, we can assume the presence of local sea transgression in this study area during the Lower Cretaceous.
This paper is the results of evaluated of water parameters (COD, pH, electrical conductivity), the content of major ions (Ca2+, Mg2+, Na+, K+, NH4 +, HCO3–, Cl–, SO4 2–, NO3 –) and microelements (Co, Ni, Cu, Zn, Cd, Pb, Sr, Ba, Mn) for 12 springs in the Bogorodsky and Losino-Petrovsky districts of the Moscow region. The waters are slightly acidic-near-neutral (pH 5.5–7.5) with the mineralization from 0.07 to 0.5 g/l, the total hardness is 0.63–5.7 mg- eq/l, the composition of the water is variable. Spring waters are divided into four groups: Cl-SO4-HCO3-(Mg)-Ca; (SO4)-HCO3-Cl-Na-Ca; (Cl)-HCO3-Ca; and mixed composition. Based on the thermodynamic calculation using the Visual-MINTEQ, it was found that the predominant dissolved forms of Ba, Sr, Mn, Zn, Cd, Ni, Co in the waters in the waters of the surveyed springs are free ions. For Cu and Pb, the factors for the formation of migration forms are the predominant anions of water, as well as the presence of organic matter in water. COD values and nitrogen compaund in the waters of individual springs are indicate that the formation of the composition of spring waters is associated with the infiltration of atmospheric precipitation through the modern sediments subject to antropogenic press. The values of other sanitary-chemical indicators (mineralization, pH, total hardness, chlorides, sulfates, mag- nesium, sodium, manganese), the content of standardized microelements are lower than their maximum permissible concentrations in drinking water.
The results of flowmeter tests of wells in the upper part of the layered rock massif indicate a model of the permeability medium in the form of separate horizontal thin fracture zones, separated by layers with a thickness of several meters. A study of pumping was done on a model in cylindrical coordinates for two thin aquifers. The upper one works with a constant pressure in pumping well, determined by the position of the zone, and a decreasing rate, and the lower — with an increasing rate, is additional to the pump rate. The filter intervals of the central and the only observation well are the same. The processing of pumping results using the commonly used Jacob method showed the main features — strong differences in transmissivity in different variants of well locations, unrealistically large values of the storage coefficient, ultra-small calculated radius of the pumping well.
The article discusses the results of experimental studies of the content of unfrozen water (Ww) in frozen soils of various granulometric composition with a degree of congestion from 3 to 100% (in increments of 10%). The obtained regularities Ww = f(t°C) are discussed. The role of the organic matter content in the formation of the phase composition of moisture in the temperature range from 0 to –18 °C. is estimated. Attention is focused on the consideration of the regularities of humidity changes due to unfrozen water with a degree of congestion above 50%, when soils according to GOST 25100-2020 are referred to peat. The regularities of the change in Ww from the degree of congestion at fixed temperatures are given.
We present the results of seismoacoustic works carried out in the Petrozavodsk Bay of Lake Onega, the goal was to study a near-surface geological section. Seismoacoustic investigations were presented by the reflection method in a modification ultra-high resolution seismic survey. During the office work, the data were processed and interpreted, in which five seismic complexes were identified and correlated with the information about the lake structure. The result of the work was the maps construction of all five identified reflecting horizons covering all Petrozavodsk Bay. It was possible to estimate the sediments abundance and thickness corresponding to each complex.
The paper considers three algorithms of kinematic migration (transformation of time fields of normal rays into reflecting boundaries) based on the variational theory of ray tracing developed by Professor of the Department of Seismometry and Geoacoustics of the Geological Faculty of Moscow State University T.I. Oblogina. The results of numerical experiments on theoretical models of layered media of varying complexity have revealed significant drawbacks of the “classical” variational algorithm for solving the inverse kinematic problem. Two mod- ifications of the “classical” variational algorithm are proposed in terms of calculating the starting angle of the rays’ exit from the Earth’s surface, leaving unchanged the principle of taking into account the curvature of seismic rays and refraction at intermediate boundaries: a variational algorithm using “image rays” and a kinematic migration algorithm for layered media with variable reservoir velocities, taking into account the slope of each boundary. The results obtained on theoretical models of complex environments demonstrated high efficiency of solving the inverse kinematic problem by a modified kinematic migration algorithm that takes into account the slope of each boundary.
