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Vol. 18 (2015 year), No. 2
Nikiforov S. L., Koshel S. M., Sorokhtin N. O., Kozlov N. E.
Seabed digital elevation models and some possibilities of their morphometric analysis
Seabed bathymetry is an important component of marine geology and geomorphology activity, so as cartography and paleogeography, geoecology and hydroacoustics and other applied areas of research also. General seabed digital elevation model (DEM) could be the basement in the definition of "key" shelf areas for further detailed study, including sound profiling. All of them are required at the stage of industrial planning, construction and exploration, definition of geo-hazard, for the monitoring activity and also required to repel potential threats, including natural ones, etc. Developed methods are the most adequate approach for optimization of material costs, considering the large amount, sometimes huge, costs of marine field research. Simulation of seabed relief within large areas is always connected with the limit of hydrographic survey data. From the other hand, detailed knowledge of the bottom topography for software-based automatic processing is not expected in the near future and is not possible now due to technical reasons. Thus, all available geological and morphological information should be used. Our technique is based on the analysis and digitizing of the navigation charts of different scale and drawing manually additional isobaths under developed classification of seabed relief. Using the DEM it is possible to determine some series of morphometric parameters based on calculating the derivative grid models
(in Russian, стр.8, fig. 6, tables. 0, ref 9, Adobe PDF, Adobe PDF 0 Kb)
Vol. 19 (2016 year), No. 1, DOI: 10.21443/1560-9278-2016-1/1
Sorokhtin N. O., Nikiforov S. L., Koshel S. M., Kozlov N. E.
Geodynamic evolution and orphostructural analysis of the Western sector of the Russian Arctic shelf
The paper considers issues of the Barents Sea shelf geodynamic evolution and influence of basement geologic structural processes on seabed morphology in their interaction. The obtained data have made possible to assume that the Norwegian-Mezenskaya rift system, Voronin graben, St. Anne and Victoria grabens were formed at the expense of the lithosphere stretching processes, but the Vostochno-Barentsevomorskaya basin and Medvezinsko-Edzinskaya area of depressions developed on the initial stage of lithosphere plate evolution due to collision of several island arcs and now all of them are outliers of the ancient oceanic crust. The technique of morphostructural analysis developed by the authors has allowed solve the inverse problem, and under morphological approach split all largest depressions on two main genetic types that confirm received geodynamic conclusion
(in Russian, стр.0, fig. 0, tables. 0, ref 0, Adobe PDF, Adobe PDF 0 Kb)
Vol. 20 (2017 year), No. 1, DOI: 10.21443/1560-9278-2017-20-1/1
Kozlov N. E., Fomina E. N., Martynov E. V., Sorokhtin N. O., Marchuk T. S.
On reasons of specific composition of the Keivy domain rocks (the Kola Peninsula)
The Keivy domain differs from the other structures of the Kola region by the specific composition of the metamorphic complexes, the presence of the oldest for the region alkaline granites and gabbroanorthosites associated with them as well as by the presence of unique mineral deposits. The previous studies of the Keivy structure showed that within this structure there are metasedimentary formations that differ from both Early Precambrian metasedimentary rock associations of the Kola region and Phanerozoic sedimentary complexes in the content of titanium and the ratio Al2O3/SiO2. The present study confirms the correctness of this conclusion. The authors have attempted the search of the generalized indicator (trend) describing the nature of changes in the chemical composition of rocks in the transition from Low-Ti to High-Ti varieties of rocks (with simultaneous increase in the ratio Al2O3/SiO2). To solve this problem the method of search of differences in the specified number of sets has been used with the partial order relation introduced by the researcher. The formations of the same type and age, namely metapelites of the Chervurtskaya suite of the Keivy series, have been chosen as the informational basis. Such indicator has been found. It describes the process which besides a significant titanium input was accompanied by a simultaneous increase in the content of CaO and decrease in the content of Al2O3, ?Fe, and Na2O. It must be emphasized that the obtained trend is not related to the supergene processes characterized by the similar behavior of titanium with aluminum and iron which is especially clearly exhibited in the formation of crusts of weathering. The location on this generalized indicator of the points of rock compositions of all strata of the geological section of the Keivy domain taken far or close to alkaline granites corresponds to the position of less or more titaniferous rocks, thus confirming the assumption of a metasomatic alteration of the latter. The fact that all the metasedimentary Keivy formations are subjected to metasomatic alteration most probably related to the Archean complexes of alkaline granites, which is confirmed by direct geological observations of the relationships of the Lebyazhinskiye and Chervurtskiye rock complexes with alkaline granites, allows us to speak about their Archean age.
(in Russian, стр.12, fig. 4, tables. 1, ref 29, Adobe PDF, Adobe PDF 0 Kb)
Vol. 20 (2017 year), No. 1, DOI: 10.21443/1560-9278-2017-20-1/1
Sorokhtin N. O., Lobkovsky L. I., Kozlov N. E.
Metallogeny of subduction zones
The paper deals with the multistage mechanism of the Earth's crust enrichment in ore elements in underthrust zones. The processes of metamorphism and the formation of hydrothermal solutions at pulling of the watered oceanic lithospheric plate into the subduction zone have been described. Some physical and chemical transformation regularities of structural-material complexes in these areas and mechanisms of the formation of ore deposits have been discussed. Spatio-temporal patterns of the localization of a number of endogenetic and exogenetic deposits have been described using metallogeny of the Ural and the Verkhoyansk-Kolyma Fold Belts as an example. It has been shown that in nature there are several effective mechanisms of the enrichment of the crust in ore minerals. One of them is the process of pulling into subduction zone of metalliferous sediments and ferromanganese crusts as well as seabed nodules, their metamorphic transformation, partial melting and transition of ore components into magmatic melts and mineralized fluids. In the future this leads to the release of ore material by magmas and hydrothermal solutions into the folded formations of island-arc and Andean types and the formation of igneous, metasomatic and hydrothermal deposits. Another, yet no less powerful natural mechanism of a conveyor enrichment of the crust in ore elements is the process of destruction and sedimentation of mineral deposits formed in the folded areas as well as the formation of placers and their transfer to the marginal parts of the continent. Later, during the collision of active and passive margins of two lithospheric plates, such as the collision of the Kolyma Massif with the eastern part of the Siberian craton in the middle of the Mesozoic there was a thrusting of a younger lithospheric plate over a more ancient one. As a result, the sedimentary sequences of the passive margin of the Siberian plate were submerged and partially melted by the basic magmas intruded in the bottom of the cut. This led to the transition of a part of ore elements from placers to igneous rocks of granitoid composition and fluid solutions, thereby forming magmatic, metasomatic and hydrothermal mineral deposits. Cyclic enrichment of the Earth's crust in this way can repeatedly manifest itself in the history of the Earth and lead to the enrichment of ore deposits from the ancient complexes to the young ones. Studying processes of geodynamic evolution of the structural-material complexes of continental and oceanic lithosphere is important to understand the processes of ore genesis in the Earth's crust. Most endogenetic deposits are closely connected with the processes of metamorphism, magmatism and hydrothermal activity and are usually formed at the margins of lithospheric plates. A part of exogenetic deposits is also genetically connected with endogenetic and is formed due to their destruction. The regularities of ore genesis in underthrust zones described in the paper cover only a part of the natural processes of the Earth's crust enrichment in ore minerals. The paper has also focused on polycyclic and conveying mechanisms of the formation and transformation of ore elements in subduction zones, as well as on the mechanism of remobilization of orebearing deposits and their joint transfer to the upper structural layers of the folded system and the formation of ore-bearing volcano-plutonic associations.
(in Russian, стр.18, fig. 5, tables. 0, ref 35, Adobe PDF, Adobe PDF 0 Kb)
Vol. 21 (2018 year), No. 1, DOI: 10.21443/1560-9278-2018-21-1
Sorokhtin N. O., Nikiforov S. L., Kozlov N. Ye.
Crust-mantle branch of the global carbon cycle and origin of deep-seated hydrocarbons
The processes of multi-stage and polycyclic transformation and transfer of carbon in the crust and mantle have been described. The sediments drawn in the plate underthrust zones break down, become transformed and altered by metamorphic events, and part of the newly formed carbon compounds is transferred by the mantle convective currents to rift zones of the mid-oceanic ridges and carried up to the surface as hydrocarbons of various composition and carbon dioxide. This material becomes re-deposited on the sea floor as sediments forming carbonaceous and carbon-bearing units. As a result of multi-stage mechanism of physical and chemical transformations in the crust-mantle areas of the Earth hydrocarbon compounds acquire features of abiogenic origin remaining, in fact, exogenic. The revealed crust-mantle carbon cycle represents part of a global process for the cyclic carbon transfer from the atmosphere to the mantle and back. The scale of its manifestation is likely not so wide, and numerous small (mm and portions of millimeters) particles of exogenic substance and dispersed carbon drawn in the plate underthrust zones form a stable geochemical tail of the crustal direction in the mantle propagating in the plane of convective currents motion. The scale of this process may be indirectly suggested by the volumes of hydrocarbon and carbon dioxide de-gassing and hydrogen in the rift systems of the Earth crust. The amount of generated hydrocarbon gases with deep-seated origin cannot form large gas and oil-and-gas fields since their significant part is transferred to the atmosphere. Just some portion of compounds may be deposited in oceanic sediments and generate gas-hydrate pools.
(in English, стр.10, fig. 6, tables. 0, ref 43, adobe PDF, adobe PDF 0 Kb)
Vol. 22 (2019 year), No. 1, DOI: 10.21443/1560-9278-2019-22-1
Sorokhtin N. O., Kozlov N. E., Kalatchev V. Yu.
The first find of diamond on the Sredny and Rybachy Peninsulas in the north-eastern Baltic Shield
The regular features of the region's spatial-temporal evolution have been discussed. Based on geodynamic analysis and the time scale of the crust formation in the eastern Baltic Shield, it is defined, that the most promising search areas for diamond-bearing rocks are intersections of deep lithospheric faults and discovered belts of possible diamond-bearing kimberlitic magmatism. The paper suggests the most promising search areas for diamond-bearing kimberlitic explosion pipes that can be united in the single diamond-bearing Norwegian-Mesensky belt. Prospecting for diamonds was carried out in the area of the Rybachy and Sredny Peninsulas in 2005–2007. Detailed decoding of large-scale aerial photographs and in situ measuring of fractures in the northern margin of the Sredny Peninsula allowed defining prospective intersection nodes of deep faults. Heavy mineral concentrate has been sampled here and indicated diamonds and associated minerals. They can suggest either native wash-out origins, or immediate scouring of Paleo-marine terraces that used to be rich in these minerals. No magmatic explosion pipes of the kimberlitic composition have been found here. It can be due to a lack of geological data on the region obtained by large-scale geophysical methods. The diamond finds have made it possible to recommend enhancing such investigations and paying more attention to this issue. We take into account that the Riphean sedimentary complexes of the Rybachy and Sredny Peninsulas are formations of the passive continental margin at that time and the watershed of the Musta-Tunturi Range is close to the study area. Based on that, we suggest that the matter transfer was not significant, just first km or, probably, first tens of km. Therefore, bedrocks of diamond-bearing explosion pipes should be prospected for close to the location of the diamond find
(in English, стр.12, fig. 11, tables. 1, ref 5, Adobe PDF, Adobe PDF 0 Kb)
Vol. 22 (2019 year), No. 1, DOI: 10.21443/1560-9278-2019-22-1
Ul'yantsev A. S., Chickiryov I. V., Nikiforov S. L., Sorokhtin N. O., Melousov A. А., Ananiev R. A., Dmitrevsky N. N., Libina N. V.
Lithological characteristics of the modern sediments of the Pechora Sea
The Pechora Sea is of great economic importance for the Russian Federation. Knowledge of the history of the shelf of the Russian Western Arctic seas is impossible without studying the modern processes of sedimentation and lithological structure of the sections. Therefore, the spatial distribution and variety of types of bottom sediments was studied by direct methods of geological testing in August – September 2018 during the 38 route of the research vessel "Academician Nikolai Strakhov". The link of lithological types of bottom sediments to the forms of bottom topography of different origin was established. The characteristics of the late Quaternary sedimentary cover in the Pechora Sea were revealed. The sampling of bottom sediments of the Pechora Sea was carried out using a dredger and a shock ground tube. The sampling points were selected based on the materials of continuous seismic profiling and bathymetric bottom survey. As a result of the study, the following types of bottom sediments were identified: pelitic mud, aleurite-pelitic mud, clay, silt, sand, moraine deposits. The lithological characteristic of various types of the Pechora Sea modern sediments has been presented in the paper. It has been shown that in the most shallow water – the southern and central part of the Pechora Basin – psammitic facies dominate. This is connected with the intensive flow of sandy-silt material from the continent due to river runoff. In the northern – the deepest part of the Pechora basin – thin sediments (pelitic and aleurite-pelitic silts) are mainly distributed. The presence of moraine deposits in the southeastern part of the Pechora Sea suggests that there was a glacier here during the Late Valdaian, while the rest of the Pechora Basin was a lowland with a cryoarid subaerial landscape
(in Russian, стр.8, fig. 4, tables. 0, ref 6, Adobe PDF, Adobe PDF 0 Kb)
Vol. 23 (2020 year), No. 1, DOI: 10.21443/1560-9278-2020-23-1
Chickiryov I. V., Ulyantsev A. S., Nikiforov S. L., Sorokhtin N. O., Ananiev R. A. , Dmitrevsky N. N., Libina N. V., Kovalev G. A.
Comparative lithological characteristics of modern sediments of the Kara and Pechora Seas
Global climate warming and increased anthropogenic pressure on the Arctic shelf contribute to the development of thermoabrasive processes along the coast of the western sector of the Russian Arctic.Comprehensive geophysical, hydroacoustic, geological-geomorphological, and hydrophysical scientific studies were carried out within the Kara and Pechora Seas in June – July 2019, during the 41st cruise of the R/V Akademik Nikolai Strakhov.To test modern sediments, bottom grabbers and shock tube were used. The sampling points were selected based on the materials of continuous seismic profiling and bathymetric bottom survey.As a result of the studies, mapping of the relief and modern sediments within the Kara and Pechora Seas has been carried out and it has been found that the Pechora basin is characterized by various types of sediments and deposits (pelitic mud, aleurite-pelitic mud, clay, silt, sand, moraine deposits), and the Kara Sea is mainly inhabited by thin sediments (pelitic mud). A small amount of sand and siltstone among the bottom sediments of the Kara basin should be associated with an insignificant introduction of terrigenousclastic material from the continent and its deep water. The wide distribution in the southern and central parts of the Pechora Sea of psammiticfacies is due to its shallow water, intensive supply of a large amount of sand-silty material by river flow, processes of solifluction and thermal abrasion of the coasts. In 2020, the next flight of the R/V Akademik Nikolai Strakhov is planned to continue the study of the upper sedimentary stratum and topography of the seabed of the western sector of the Russian Arctic. The purpose of the study is to substantiate the most likely scenario for the development of changes in the natural environment on the shelf, associated primarily with a reduction in the area of ice cover.
(in Russian, стр.8, fig. 7, tables. 0, ref 9, AdobePDF, AdobePDF 0 Kb)
Vol. 24 (2021 year), No. 1, DOI: 10.21443/1560-9278-2021-24-1
Chickiryov I. V., Tolstobrov D. S., Sorokhtin N. O., Nikiforov S. L., Melousov A. А., Ananiev R. A., Dmitrevsky N. N.
Lithological characteristics of modern sediments in the southwestern part of the Kara Sea shelf
In August – September 2020, during cruise 49 of the R/V Akademik Nikolay Strakhov, comprehensive geological, geophysical, hydroacoustic, geomorphological and hydrophysical research studies of the western segment of the Arctic zone within the Pechora and Kara Seas began in 2018–2019 were continued. As previously, the work was aimed at mapping the relief and modern sediments in order to assess the possible negative consequences of changes in natural conditions on the Arctic coast of the Russian Federation. The main purpose of the research was to assess the evolution of natural environments within the southwestern part of the Kara Sea shelf in connection with the observed global climate change in the Arctic, as well as with the expected increase in anthropogenic load on the Arctic shelf due to the development of oil and combustible natural gas fields. Bottom grab and a shock ground tube were used to obtain samples of recent sediments of the Kara Sea. The sampling sites were determined based on the analysis of data from bathymetric bottom survey and continuous seismic profiling. During the research, the boundaries of the distribution of various facies of bottom sediments within the southwestern part of the Kara Sea shelf have been clarified. The main feature of the modern bottom sediments in the southwestern part of the Kara Sea shelf is a wide areal distribution of thin facies – pelitic muds. Along the eastern and southern coasts of the Archipelago Novaya Zemlya, a distribution zone of iceberg sediments with a width of at least 150 km has been established. The formation of icebergs should be associated with the movement of the Novaya Zemlya cover glacier, formed 30–20 thousand years ago during the Sartan Ice Age. As the studies have shown, the general Holocene transgression in the Kara Sea was periodically replaced by short regressions, at least in the southwestern part of the basin.
(in Russian, стр.10, fig. 8, tables. 0, ref 9, AdobePDF, AdobePDF 0 Kb)
Vol. 26 (2023 year), No. 1, DOI: 10.21443/1560-9278-2023-26-1
Kozlov N. E., Sorokhtin N. O., Marchuk T. S.
Evolution of the Keivy domain in the Precambrian
Detailed geological and petrogeochemical studies carried out using the techniques developed by the authors have made it possible to complete the picture of the formation of supracrustal complexes of the Keivy structure. The studies have shown that the metasedimentary complexes of the Chervurt and Vykhchurt suites were formed mainly due to the material of the underlying strata. In the development of the Vykhchurt Formation, starting from its upper part, the material of the domains surrounding the Keivy takes an active part. The authors have come to the conclusion that at least the middle part of the Keivy section was formed as a result of washing and redeposition of the material of the structure itself, it confirms the conclusions about the presence of redeposited weathering crusts within the Keivy. The results obtained testify to the correctness of the earlier conclusion about the formation of the Keivy structure under conditions most similar to the middle massifs, and to a certain extent explain the formation of a giant deposit of aluminum raw materials within the Keivy.
(in Russian, стр.6, fig. 1, tables. 2, ref 12, AdobePDF, AdobePDF 0 Kb)