Vol 73, No 2 (2018)
- Year: 2018
- Articles: 12
- URL: https://journals.rcsi.science/0145-8752/issue/view/10687
Article
The Tendencies of the Development of the Mineral-Resources Sector at the Turn of the Century
Abstract
Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base.
The Relationship between the Taimyr Collision and Trap Magmatism Based on Geological Data and Modeling Results
Abstract
Collision and trap magmatism are spatially conjugated within the Taimyr fold region. Trap magmatism is related in time to late collision and postcollision stages. Supercomputer modeling makes it to possible to reveal the potential for mantle and crust heating at the late collision stages, accompanied by largescale basaltic magmatism.
The Correlation of the Upper Cretaceous Zonal Schemes of the Eastern European Platform Based on Foraminifera, Radiolaria, and Nannoplankton
Abstract
This article proposes a biostratigraphic scheme for the Upper Cretaceous of the East European Platform on the basis of the distribution in the sections of three groups of microfossils: foraminifera (both planktonic and benthic), radiolarians, and nannoplankton. Most of the stage and substage boundaries are confirmed by macropaleontological data. The most divided units are those distinguished based on benthic foraminifers and nannoplankton. The diversity of these microfossils and their constant presence allowed us to identify zones and subzones, while it is possible to subdivide only the beds by planktonic foraminifers and radiolarians. The most favorable stages in the development of plankton biota can be considered the Turonian–Coniacian interval when the basins of the East European Platform experienced an intensive influence from warm waters of the Tethys Ocean. The global Campanian cooling is clearly recorded, which affected the taxonomic diversity of all microfossil groups.
The Burrows of Decapod Crustaceans from Paleogene Deposits of the Middle Volga Region: Paleogeographic Implications
Abstract
The description of a new find of the burrows of decapod crustaceans from Upper Paleocene and Lower Eocene deposits relating to two ichnotaxa (Thalassinoides suevicus Rieth and Ophiomorpha nodosa Lundgren) clarifies their stratigraphic position and shows the paleogeographic significance of determining eustatic phases in the development of the semiclosed Early Paleogene Volga–Caspian basin.
The Features of the Transformation of Organic Matter of Precambrian Carboniferous Rocks of the Ukrainian Crystalline Shield
Abstract
The main features of the transformation of organic matter (OM) in the greenschist, amphibolite, and granulite facies of metamorphism are considered based on the example of the Ukrainian crystal shield. The occurrence area and OM content in highly carbonaceous ancient rocks are characterized. The composition of primary sedimentary rocks and the processes of accumulation of biophile elements under the OM transformation are reconstructed.
The Effect of Aggregation of Impurity Nitrogen on Diamond X-Ray Luminescence
Abstract
Two samplings of 65 diamond crystals divided by the intensity of a slow X-ray luminescence component are studied from the Arkhangel’skaya and Karpinskogo-1 pipes. IR and EPR spectroscopies revealed a relationship between the nitrogen A and P2 centers of the diamonds and the presence of a slow X-ray luminescence component. Its absence in most diamonds with high content of P1 (C) centers is explained by the low number of A and P2 centers.
An Ordovician Age of the Dunite–Wehrlite–Clinopyroxenite Banded Complex of the Nurali Massif (Southern Urals, Russia): U–Pb (SHRIMP) Zircon Age Data
Abstract
The data on the geochemistry and geochronology of zircons from wehrlites and clinopyroxenites of the dunite–wehrlite–clinopyroxenite banded complex that lies at the base of the crustal section of the ophiolite complex of the Nurali massif are presented. The obtained U–Pb age of the banded complex of 450 ± 4 Ma differs markedly from the previous age data. According to REE distribution patterns zircons from ultramafic rocks are attributed to the magmatic type and they indicate the age and supposed genetic similarity of the above rocks with lherzolites and dunites from the mantle section of the Nurali massif.
A Liquidus Thermobarometer for Modeling of the Magnetite–Melt Equilibrium
Abstract
A liquidus thermobarometer for the magnetite–silicate melt equilibrium was obtained by processing of a sample of 93 experimental equilibria of magnetite with basic melts using the methods of multidimensional statistics. The equations reproduce experimental data in a wide range of basic compositions, temperatures, and pressures with low error. Verification of the thermobarometers shows that the maximum error in liquidus temperature reproduction does not exceed ±7°C. The level of cumulative magnetite in the vertical sections of the Tsypringa, Kivakka, and Burakovskii intrusions is predicted with errors from ±10 to ±50 m.
Anthropogenic Transformation in Engineering–Geological Megastructures in Russia
Abstract
Engineering activities lead to the anthropogenic transformation of engineering–geological conditions in different areas of Russia. A differential estimate has been made for changes in individual components of engineering–geological structures: relief, upper section soils, underground waters, depth of seasonal soil freezing and thawing, and current geological processes. The general integrated evaluation of the anthropogenic transformation of engineering–geological megastructures in Russia has been made on the basis of differential estimates of the components.
The Effect of Geofiltration Heterogeneity of Bottom Sediments on Groundwater Discharge in a Small River Basin under Natural and Disturbed Conditions
Abstract
A regional model of a small river basin with a catchment area of approximately 1000 km2 is considered. The model was developed to evaluate the possible influence of groundwater intake on river runoff. The model is calibrated to the measured levels of groundwaters and discharges of this river. Geophysical and hydrometric surveys have allowed us to characterize the heterogeneity of the conductivity of the bottom sediments along the riverbed. The reduction in the river discharge considering this heterogeneity is greater by 25% than the reduction in the discharge calculated without taking it into account. Thus, consideration of the heterogeneity of bottom sediments for more reliable estimation of an influence of water intakes on the environment is recommended.
The Influence of Conductivity on the Reflected Ground Penetrating Radar SIgnal Amplitude
Abstract
Within the ground-penetrating radar (GPR) bandwidth a subsurface materials is considered to be an ideal dielectric, which is not always the case. We have developed the dependence of the reflection coefficient of electromagnetic waves with regard to conductivity, which showed a significant effect of the difference in conductivity on the reflectivity and signal amplitude. This was confirmed by physical modeling. The electrical conductivities of a geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground-penetrating radar can be used to solve the problem of mapping of the halocline or to determine water contamination.
Brief Reports
The Composition and Reservoir Properties of the Deposits of the Bazhenov Formation in the Central Part of the Tundrin Depression
Abstract
The section structure was characterized according to the lithological and petrophysical studies of the core from the Bazhenov Formation that has been uncovered in the central part of the Tundrin Depression. The productive oil intervals where the reservoirs of the pore and fissure-pore types occur were identified.