Preview

Moscow University Bulletin. Series 4. Geology

Advanced search
No 3 (2023)
View or download the full issue PDF (Russian)
3-10 333
Abstract

The transition towards low-carbon energy technologies based on renewable energy sources will come with an increasing demand for raw mineral materials in the coming decades. This investigation is to define what metals and industrial minerals will play a critical role in scaled-up production of these technologies.

11-21 379
Abstract

The Liskin fault zone located in the southeastern part of The East European Platform on the border of two large neotectonic structures — the Voronezh Uplift and the Oka-Don basin is considered. A concentration of earthquake epicenters is confined to the fault zone and the adjacent territory. The neotectonic structures of the territory, relief, structure of the multi-depth and age horizons of the sedimentary cover, basement, crust, Moho surface are investigated, and the causes of neotectonic and seismic activity of the zone are determined. The Liskin fault at the present time developing as a thrust with right component under the conditions of submeridional compression and the adjacent territory is under the influence of multidirectional tectonic compression stresses: from the north, from the Oka-Don basin and from the south, from the Caucasian segment of the Alpine collision belt. This is reflected in the morphology and structure of the newest structures. The deformation of multi-depth horizons as well as the Earth’s surface and the activating of seismicity are associated with the submeridional compression. The deep material and structural inhomogeneities of the Earth crust are of great importance. For the first time in the newest structure of the south-eastern part of the East European Platform, the collision area of two oncoming submeridional stresses that caused active seismicity has been identified.

22-30 222
Abstract

The paper contains description of systems fissures and low-amplitude faults in Upper Cretaceous rocks of Chufut-Cale “cave town” outskirts. Analysis of orientation and kinematics of breaks and fissures’ parageneses allowed to restore stress-fields of Alpine tectonic epoch and their rough order. A guess of sublatitudinal compression appearance in Mountaineous Crimea was suggested.

31-38 318
Abstract

A kinematic model was built for the seismic profile passing through the Pegtymel inverted rift (Chukchi Sea). The main stages of rift formation have been identified: (1) 125–34 Ma; (2) 34–20 Ma; (3) 20–0 Ma. The identified stages are compared with the history of the development of the Eastern Arctic.

39-48 319
Abstract

A new anomalous section of the Bazhenov formation was described on the territory of the Urengoydeposit in the northern part of Western Siberia. This article presents descriptions of mesostructural complexes in the core, on the basis of which a new model for the formation of the anomalous section of the Bazhenov formation was proposed. It was found that the formation of the mesostructural complexes occurred at different stages of the landslide and when its body moved along the uneven surface of the detachment. In the formation of large injection “sand veins” in the studied section, the main role was probably played by the landslide-induced grain flow from the coastal shallow water area. The penetration of its sandy material into the rocks of the Bazhenov formation and, to a lesser extent, the Achimov formation occurred due to the energy of hydraulic shock and hydraulic fracturing along layer-by-layer and secant fractures.

49-62 405
Abstract

The Caspian Sea is one of the most perspective areas for oil and gas exploration. Significant hydrocarbon reserves are contained in the polymictic sand reservoirs of the lower cretaceous (Aptian-Albian) deposits of the North Caspian fields, which are characterized by an irregular distribution of pelitic and silty fractions. This results in high residual water content and low permeability, poor consistency of filtration-volume properties between them. This predetermines high heterogeneity of reservoirs in hydrocarbon reservoirs and unusually low specific electrical resistivities when producing water-free hydrocarbon inflows. As the authors’ studies have shown, the most important reason for the complex structure is the intense bioturbation of deposits virtually throughout the productive section, which actively affects redistribution of clay material in the reservoir rocks and ultimately leads to a decrease in the resistivity of reservoirs to the point where they can be classified as low resistivity.

63-76 339
Abstract

This paper is focused on the tourmaline and associated minerals from veinlets cutting chromitite of the Kamennoozerskoe occurrence, which is a part of the Shabrovskoe district in the Central Urals. Tourmaline belongs to the dravite—oxy-dravite solid solution series, contains Cr (0,52–2,06 а.ф.), Ni (до 0,03 а.ф.), V (до 0,02 а.ф.) The Raman spectroscopy indicates Fe3+ in tourmaline. Rutile associated with tourmaline contains, wt %: 4.68–11.69 Sb2O5, 2.00–8.02 Cr2O3, and 0,88–1,14 WO3. Combination of high Sb and Cr contents in rutile is established possibly for the first time. It is suggested that tourmaline and associated minerals from the veinlets cutting chromite were formed in oxidizing environment.

77-87 224
Abstract

An example of unconventional modelling using when groundwater table regime data is considered as a verification object has been presented in the article. A models set has been developed for the site where sources of pollution are situated. The models set describes such processes as precipitation transformation on the earth surface, unsaturated flow in vadose zone and groundwater flow. Based on modelling results correlation between seasonal variation amplitudes of groundwater levels measured at monitoring wells and annual groundwater recharge has been proved, inconsistent monitoring data have been revealed.

88-97 501
Abstract

This article shows the possibilities of using on-board gravimetry and hydromagnetometry in combination with high-resolution seismic surveys in the framework of site surveys on the Arctic shelf. Geotechnical surveys were carried out in the southern part of the Kara Sea shelf on a study area of 25 km2 in order to identify potentially hazardous areas for setting up a floating drilling rig. The studies were carried out using a regular network of observations, consisting of 51 line and 26 secant profiles. The length of each profile is 5 km. Gravimetric research were carried out with the Chekan-AM marine on-board gravimeter in conjunction with magnetometric research using SeaSPY 2 towed marine magnetometers. The depth of research when performing engineering and geological surveys using the presented set of methods is the first 100 meters, up to 1 km. In this case, objects and phenomena of both technogenic and geological nature can represent a potential hazard. As the experience of carrying out this type of work in the south of the Arctic shelf shows, paleoincisions and paleovalleys are common hazards of the geological nature of the region under study. These structures are traditionally filled with weakly consolidated, often gas-saturated, sediments with inclusions of coarse-grained material. Paleoincisions are clearly manifested in the high-frequency component of the magnetic field, and the local component of the anomalous magnetic field was calculated to reveal them. As a result of a complex interpretation of gravity field anomalies and magnetic survey data, a curved linear zone was localized, crossing the entire study area. The identified anomalous zone is confined to the boundaries of the paleoincision, which was originally discovered according to seismoacoustic studies. Based on the results of gravity surveys, an area of negative anomalies was identified in the eastern part of the study area. According to the materials of seismoacoustic in this zone, paleocuts of a complex spatial and deep configuration are traced. It is noteworthy that these structures are not manifested in a magnetic field. Based on the obtained values of the gravitational field and seismoacoustic data, a seismic-density section of meridional strike was constructed across the entire area. As a result of 2D density modeling, the densities for the undercut paleoincision were selected and two deconsolidations were found at a depth of 200 meters. One of the model “artifacts” does not appear according to seismoacoustic studies and hydromagnetometry. The detected areas of decompaction can be caused by the gas saturation of the sedimentary strata and must be taken into account when setting up a floating drilling platform. The interpretation of the anomalous gravitational field in the specified complex of geophysical methods with a priori geological information makes it possible to predict the density structure of the studied rock mass and gives recommendations for further research.

98-112 400
Abstract

The types of magmatic sulfide ores on the Western flank of the Oktyabrsky deposit have been studied, and the patterns of their distribution have been established. The features of ore-bearing rocks within the western branch of the Kharayelakh intrusive Talnakh ore field have been studied. The morphology of ore bodies is described and mineralogical characteristics of ore types in the western part of the Kharaelakh intrusion are given according to drilling data of recent years. The data of earlier studies on the types of ores and their spatial placement on the flanks of the Oktyabrsky deposit are summarized and confirmed. The main patterns of spatial distribution, composition and morphology of copper-nickel sulfide ore deposits on the western flank of the Oktyabrsky deposit are identified, which can be used as search criteria for further geological exploration.



ISSN 0579-9406 (Print)