JournalTOCs

Moscow University Geology Bulletin
Journal Prestige (SJR): 0.311

Number of Followers: 0

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1934-8436 - ISSN (Online) 0145-8752
Published by Springer-Verlag

[2469 journals]

Bound Water in the Bazhenov Formation Rocks Before and After Extraction of
Hydrocarbons
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  Abstract: The results of determining the contents of different types of bound water by the hygrometric method and the adsorption isotherm method are presented for the first time for extracted rock samples of the Bazhenov Formation. All the obtained water sorption isotherms have a well-defined S-shape, which allows calculation of the maximum possible amounts of bound water of different types (mono-, poly-, and capillary condensation) in the samples. The inflection points of the isotherms of the extracted samples fully correspond to the inflection points of the isotherms of the native samples. Based on these results, it is possible to further estimate the specific surface area of the samples and then to determine the hydrophobicity coefficient and the parameters of the associated oil saturation.
  PubDate: 2022-04-01
The Features of Seismic-Gravity Modeling in Different
Physical–Geological Situations
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  Abstract: Abstract—Using actual examples, we have studied the abilities of seismic-gravity modeling for territories that differ in the features of their physical and geological structure, scope of study, and level of data. It is shown that it is impossible to formalize a unified approach to developing a seismic-density model since the modeling technique is inevitably changed according to the physical and geological situation, as well as the completeness and the quality of a priori data. The degree of effectiveness of seismic-gravity modeling depends on the geological features of the cross-section, that is, the extent of compartmentalization of the geometry of the reflector horizons, the contrast and depth of the density boundaries, the complexity of the geological development of the region, and the acquisition parameters for the modeling.
  PubDate: 2022-04-01
The Quality of Fresh Groundwater in the Bodrak River Valley in Mountainous
Crimea
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  Abstract: This paper reports on the data on the quality of fresh groundwater in the foothills of Crimea, including the waters that are used for the water supply of the Crimean Base of St. Petersburg State University and the Bogdanov Crimean Geological Scientific-Educational Center, Moscow State University. The results of the long-term monitoring of the chemical composition of potable fresh waters have been presented and the high-priority pollutants have been identified. Hydrochemical modeling was carried out to calculate the transport forms of chemical elements and to assess their toxicity. The study area is located in an area of the active water exchange. Therefore, most of the chemical elements in the groundwater are present in concentrations below the level of biologically significance.
  PubDate: 2022-04-01
The Role of Glacial and Lithodynamic Factors in the Sedimentary Cover
Formation in the Velikaya Salma Strait (White Sea)
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  Abstract: Abstract—New data on the seafloor topography in the waters adjacent to the White Sea Biological Station of Moscow State University (Kandalaksha Bay) obtained with a multibeam echosounder (MBE) have made it possible to study the seabed relief in detail and to clarify the structure of Quaternary sediments in this area, substantially increasing the detail of the continuous seismoacoustic profiling (CSP) data obtained earlier. In the western part of the studied water area de Geer moraines have been identified for the first time in a complex of glacial deposits. These were formed during the Late Pleistocene glacial retreat in an eastern direction toward the recent deepwater part of the White Sea. In the deepwater area, according to the MBE and CSP data, the genesis of studied sediments occurred due to intensive gravitational processes at the end of the Late Pleistocene–Holocene. These new data may be indicative of “dead” ice in the White Sea Depression.
  PubDate: 2022-04-01
The Development of a General Classification of Continental
Ecological–Geological Systems
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  Abstract: Abstract—The issues of developing a general classification of continental natural and technogenic ecological–geological systems that are the subject of research in modern ecological geology, are considered. A classification that considers the composition and characteristics of the components of ecological–geological systems is proposed.
  PubDate: 2022-04-01
Zircon Isotope Dating of Jurassic Basalts from the Goitkh Volcanic Region
of the Western Caucasus
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  Abstract: Abstract—The results of U–Th–Pb-isotope dating of accessory zircons from basalts of the Goitkh volcanic region (GVR) in the West Caucasus are presented. A sample for isotope dating was taken from basalt porphyrites of the Chataltopa volcanic complex at the Tuapse River basin. Isotope geochronology using an ion probe showed that the basalts of this complex in the GVR were discharged during the Jurassic at the Aalenian–Bajocian boundary (169 Ma) within the period of the tectonic transformation of an axial trough in the rifting basin of the Greater Caucasus. Zircons in the basalts are characterized by a low Th/U ratio that is peculiar to rocks of an acidic composition; this indirectly confirms that the evolution of Jurassic rifting magmatism in the Caucasus proceeded via the assimilation of continental crust.
  PubDate: 2022-04-01
Current Crystallography: Is it Helpful to Earth Sciences'
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  Abstract: Crystallography, which originated in the 17th century at the junction of mineralogy and mathematics, later became considered as a science that is closer to physics, chemistry, biology, and even medicine. This was related to its restrained perception by the Earth Sciences scientific community. The important role of the most advanced crystallographic methods, results of studies, and ideas in the development of conceptions on the composition and structure of the Earth and planets is shown based on particular examples.
  PubDate: 2022-04-01
Introduction of the Stanovaya Ophiolites of the Faddey Block of
Northeastern Taimyr Based on Geological Data and Numerical Modeling
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  Abstract: The geological position, morphology of serpentinite bodies, limitation of ophiolite occurrences by faults, fragments of host metamorphic rocks within the Stanovaya complex of ophiolites, the character of metamorphism, the high deformation of rocks of both ophiolites and sequences at the contact zone, and mineral parageneses of secondary transformations point to the introduction of the Stanovaya ophiolites into the deeply metamorphosed Faddey Block of the Northeastern Taimyr, rather than to their obduction. The results of modeling showed that fragments of the oceanic crust introduced into the metamorphosed complexes of the continental crust during the collision may have dual origins, that is, from the primary oceanic crust, and from the newly formed crust of the back-arc basin. A detailed analysis of the chemical composition of the Stanovsky ophiolites indicates that they were formed in the suprasubduction setting of a back-arc basin, which supports the possibility of the second scenario.
  PubDate: 2022-04-01
The Distribution Model for Hydrocarbon Compounds in a Pores Space of the
Bazhenov Formation
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  Abstract: The results of studies of the molecular compositions of hydrocarbon compounds (HCCs) in open and closed pores of oil-source rocks of the Bazhenov Formation are presented. It was shown that the use of solvents of different polarities provided a method for additional HCC extraction from both open and closed pores of rock samples. The HCC compositions were regularly different in both the distribution of normal alkanes and the values of biomarker parameters that characterize the maturity and sedimentation conditions. The HCCs in open pores appeared to be more thermally transformed than those in closed pores. In both cases, the maturity could be decreased in blocked pores, especially in those sealed with resin–asphaltene alcohol–benzene-soluble compounds of various compositions in open and closed pore volumes. Pr/Ph and dia/(dia+reg)C27 were regularly higher for bitumens of open pores, whereas С29/С30 and H35S/H34S were much higher in closed pores and could be varied in blocked pores relative to the open part of an area. An improved model is proposed for the HCC distribution within a pore area. The model includes the presence of residual light HCCs in open pores along with two types of blocked pores containing HCCs blocked with resin–asphaltene compounds of various compositions in both the open and closed pore spaces.
  PubDate: 2022-02-01
New Data on the Conditions of the Formation of Gold Mineralization in the
Golets Vysochaishii Deposit, Bodaibo District, Russia
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  Abstract: The Golets Vysochaishii deposit is a sub-tabular ore body hosted by black carboniferous fine-grained aleuropelitic rocks. Fluid inclusions were studied in quartz samples collected from sulfide–quartz veins in the ore zone of the deposit. The studies provided the parameters of the ore-forming fluid. Fluids of the deposit were characterized by typical features of ore-forming fluids of the orogenic vein gold deposits. The precipitation of native gold in ores may have been stimulated by the process of carbon dioxide degassing from the fluid.
  PubDate: 2022-02-01
The Localization of Oil and Gas Fields Depending on the Types of the Most
Recent Structures on the Territory of the Western Siberian Plate
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  Abstract: Three regions have been distinguished in Western Siberia on the basis of types of hydrocarbon accumulations: Yamal–Gydan region, where gas and gas condensate fields are clustered, the Nadym–Taz region with a mixed type of accumulation, and the Latitudinal Ob region, where oil fields predominate. These regions are associated with certain neotectonics areas. We compared the location of the hydrocarbon fields and the most recent structures and established their localization signs both within each of the regions and for the entire territory of the Western Siberian Plate. It was established that oil and gas fields are generally confined to the areas of the most recent regional inherited depressions, to faults with a NW and NE-striking shearing component, to the areas with high (66–100%) and low (0–33%) lineament density, to the depressions–valleys separating the latest regional and local structures, and to the boundaries of local uplifts and depressions.
  PubDate: 2022-02-01
The Lithochemical Features and Environment of the Formation of
Late-Jurassic–Early-Cretaceous Tuff–Terrigenous Rocks at the
Ust-Belsky Mountains (Northwest of the Koryak Highlands)
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  Abstract: The results of studies of the lithochemical features of the Late Jurassic–Early Cretaceous tuff–terrigenous rocks of the Ust-Belsky and Algan terranes are presented. The rocks are medium-, fine-, ultrafine-grained quartz–feldspar and feldspar greywackes. The rocks were found to be formed synchronously to the volcanism of basic and intermediate composition under marine environment nearby the coasts. The main source of material was associated with the island arc on the west of the region. The rocks of Ust-Belsky terrane were formed at different parts of the forearc basin. Tuff-terrigenous rocks of Algan terrane were formed at the trench-slope basin.
  PubDate: 2022-02-01
Type I Kerogen in the Bazhenov Formation Rocks of the West Siberian
Petroleum Basin
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  Abstract: The Bazhenov Formation rocks have been found to contain thin luminescent layers enriched in type I kerogen, which is untypical of the majority of organic matter from the Bazhenov Formation in the central part of the West Siberian petroleum basin. The detailed characteristics of the mineral and organic parts of these layers, which are called “alginite-rich layers” by the authors, are provided and variants of their origin are proposed. The wide distribution of the luminescent alginite-rich layers over the area in a single stratigraphic interval allows their use as marker horizons, as well as for assessing the thermal maturity of kerogen. These results contribute to understanding the diversity of the processes that form the organic-rich rocks in the Bazhenov Formation.
  PubDate: 2022-02-01
The Transformation Stages of Organic Matter from the Tutleim Formation
Rocks with Respect to its Maceral Composition
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  Abstract: The results of coal petrographic and geochemical studies of the organic matter from the Tutleim Formation rocks in the area of the Em-Egovskaya summit are presented. Five macerals that compose the organic matter of the formation are identified: “standard” bituminite, “atypical” bituminite, radiolarian organic matter, alginite, and vitrinite, as well as bitumen and bituminous films being the products of the original organic matter transformation. The metamorphism in macerals during catagenesis is described and the order of their entry into the generation phase is established. It is shown that alginite is transformed first, then “standard” bituminite, “atypical’ bituminite, and last is radiolariam organic matter. The results we obtained are confirmed by the laboratory modeling of the further organic matter transformation. New bitumens are formed with different fluorescent properties compared to the original ones. These results together with the study of alterations in the compositions of both macerals and bitumens enable the assessment of the contributions made by individual organic matter microcomponents to the process of petroleum hydrocarbon generation.
  PubDate: 2022-02-01
3D Inversion of Magnetotelluric Sounding Data in the Southern Ladoga
Region
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  Abstract: The results of the interpretation of the magnetotelluric sounding data obtained in the Southern Ladoga region are presented. When performing 3D inversion, both new data obtained by the LADOGA working group in 2018–2021 and data from the 1-EV profile (the “Loop” segment) carried out in the early 2000s were used. Based on the results of automatic inversion carried out with a help of ModEM program (Egbert and Kelbert), a 3D geoelectric model of the Earth’s crust to a depth of 60 km has been constructed, which demonstrates the complex inhomogeneous structure of the studied territory. Two anomalous zones of crustal electrical conductivity oriented SE and NE are distinguished in the geoelectric model; the first one is a continuation of the well-known Ladoga anomaly. The presence of the second conductive structure confirms the results of the single-site magnetovariational soundings performed by I.I. Rokityansky in the several segments of the East European Platform in the early 1980s.
  PubDate: 2022-02-01
Application of the Methods of Structural–Petrophysical Analysis for
Estimation of Metamorphic Transformations of Host Rocks and Ores of the
Dzhusa Pyrite–Polymetallic Deposit (Southern Urals)
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  Abstract: Based on comparison of the chemical composition and a number of petrophysical and thermodynamic parameters of syn-ore and post-ore Devonian gabbroids of the Dzhusa pyrite–polymetallic deposit (Southern Urals) that were altered to various degrees, the fundamental probability of a quantitative assessment of their alteration grade related to hydrothermal post-volcanic and dynamic metamorphism is shown.
  PubDate: 2022-02-01
The Structure of Continuous Reservoirs in the Domanik Formation and
Petrophysical Interpretation Methods
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  Abstract: The properties of unconventional prospective deposits are interconnected by the processes of reservoir formation and oil and gas formation. Dispersed dolomite formed in situ during the maturation of TOC from syngenetic magnesium in the rock matrix increases the pore space of the rock, thereby forming an unconventional reservoir filled with autochthonous hydrocarbons and oil components. In the process of TOC maturation and hydrocarbon migration the TOC components are redistributed in the pore space; the released volume of rocks is thus filled with stationary resinous asphaltene substances, which sharply reduces the reservoir properties of unconventional reservoirs. As a result, the definition of “organic” porosity includes a broader concept than just the porosity of kerogen. This is a more complex physicochemical process of transformation of the organic matter itself and the redistribution of elements within the formation as a result of the maturation of TOC components and hydrocarbon migration. When assessing the oil and gas potential in the section we distinguish three groups of rocks: unconventional reservoirs with an increased TOC content and the presence of mobile hydrocarbons; bituminous rocks, in which part of the pore volume is filled with resinous-asphaltene substances, and host dense carbonate rocks without organic matter. As well, sporadically developed traditional reservoirs are distinguished throughout the section of the Domanik type rocks.
  PubDate: 2022-02-01
The Structure Tectonosphere of the Mozambique and Madagascar Ridges by
Geophysical Data
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  Abstract: The the southwestern part of the Indian Ocean, where the Mozambique and Madagascar ridges are located was studied. The ideas about the tectonic structure of these ridges are still under debate. The anomalous structure of the crust of these ridges can be explained either by underplating (thickening of the oceanic crust from below due to magmatism), or by stretching and thinning of the continental crust. Based on the data on anomalous gravitational and magnetic fields, seismotomography, and other geological and geophysical information, density modeling was performed along four profiles, which revealed differences in the crustal structure and evolution of the Mozambique and Madagascar ridges.
  PubDate: 2022-02-01
The Sedimentation Settings of the Abalak Formation and Vogulka Sequence on
the Territory of the Kamennaya Crest of the Krasnoleninsky Arch (Western
Siberia)
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  Abstract: Abstract—Various sedimentation settings were distinguished in the Middle, Late Jurassic (J2k–J3v1) on the territory of the Kamennaya crest of the Krasnoleninsky arch in Western Siberia. It was established that clayey and glauconite-clayey sediments of the Abalak Formation were accumulated throughout most of the studied area in relatively calm shallow-sea settings. Islands formed by protrusions of the pre-Jurassic basement contributed to the formation of the Vogulka sequence as a result of the removal of clastic material from the land. The lithological studies showed that gritstones and sandstones, which composed the Vogulka sequence, were accumulated unevenly. The greatest thickness of these deposits is observed to the west of the central upland. The difference in the thickness of clastic sequence on the western and eastern slopes was probably caused by the horseshoe shape of the island and the absence of active currents on the western part of the slope, as well as by its greater steepness. The upper member of the Vogulka sequence, which is composed of detrital limestones, is extremely thin (no more than 1 m), and contains numerous unconformities. These traces of erosion may be indirect evidence of the influence of the Late Oxford regression on the section structure, which was previously noted in adjacent territories.
  PubDate: 2022-02-01
The Age and Tectonic Position of Epithermal Gold Mineralization of the
Omolon Massif (Northeast Asia)
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  Abstract: This paper reports on some aspects of the genesis of industrially important Paleozoic epithermal gold deposits of the Omolon Massif. The Ar–Ar dating of the ores showed that the age of these deposits is 20–30 Ma younger than that of the volcanic complexes of the Devonian Kedon Group, with which this mineralization has been traditionally associated. The stage of post-subduction rifting, characterized by the formation of volcano-plutonic associations of shoshonite-latite series, has been identified for the Paleozoic continental marginal magmatism of the Omolon Massif. These ores were formed during this stage; their chronological boundaries are determined as 335–286 Ma. The paragenetic connection with the rifting-related shoshonite-latite series explains the specific features of the Paleozoic epithermal gold mineralization of the Omolon Massif, including the high gold–silver ratio, a low sulfide content of ore, the widespread development of fluorite and tellurides, and low values of the primary Sr isotope ratio (0.703–0.706).
  PubDate: 2022-02-01