No 2 (2019)

Local neotectonic restructuring in the North Caucasus orogene
Nesmeyanov S.A., Voeykova O.A.

Abstract

Cases of regional neotectonic restructuring are well known in the Caucasus. Detailed geotectonic zoning and identification of local structural changes are required for the engineering geological and paleoecological studies. The Baksan River valley was studied in the North Caucasus as an example of such a restructuring. The problem about the number of Quaternary volcanogenic strata and their role in structural rearrangement is considered. The Pliocene – Plio-Pleistocene volcanogenic strata cloak-like covered the Nizhnechegemsky district before the first reconstruction. Zayuksky graben (with an amplitude of 200 m) was formed in the end of Plio-Pleistocene; and a part of Pliocene- Plio-Pleistocene volcanogenic strata sank into it. Two layers with a total thickness of more than 100 m were deposited in the resulting trough. The upper strata (baxangess) contain redeposited boulder-pebbly volcanogenic material. Colluvial, subaquatic-deltoid and lacustrian facies are registered. The orographic depression in Zayuksky graben was completely filled before Eopleistocene as a result of next restructuring. The Baksan River began to form a wide well-terraced valley without any significant left tributaries there. The baxangess strata contain pebble of liparite lavas and obsidians. This pebble was used by the Paleolithic man for making stone tools. Poor roundness of pebble indicates its short transportation distance. Contradictory ideas about the initial distribution of parental volcanic rocks are considered. It is concluded on the acuteness of identifying such neotectonic rearrangements for the analysis of various paleogeographic and paleoecological changes.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):3-12
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Natural and human-induced processes
Mechanism specifics of the landslide-hazardous massif limit state formation and landslide block displacement
Postoev G.P.

Abstract

In the landslide cycle of deep block movement development, the landslide process starts with the separation of the new landslide block from the bedrock massif, and it ends with the block displacement until the steady landslide head is formed in the hotbed (on the landslide slope). The initial stressed state in the bedrock massif with horizontal earth surface (before the landslide block forms) is controlled by the Mohr-Coulomb criterion. The landslide hotbed forming as well as the sliding basis appearing cause the change in the initial stress state and the formation of horizontally oriented dissipative blocks-structures. The principal stresses are concentrated on the boundary surfaces of these structures (which are of a circular cylindrical shape). The limit state forms along these boundary surfaces of the appropriate block in the local massif zone on the contact with the landslide hotbed. The displacement occurs along the same surfaces, provided the equilibrium is disturbed. In forming the limit state of the head scarp massif, the adjacent part of the landslide massif (within the boundaries of the earlier separated landslide block) acts as an additional load (creates an active vertical pressure from the landslide mass weight) to the horizon of the landslide basis. The bedrock massif interacts with the slope at the stage of preparing block displacement. The block limit state is achieved in case the head scarp height reaches its critical value (the slope edge is higher than the landslide head). Under the soil masses weight in the new landslide block, separated from the bedrock massif, as it subsides, the soil crushes in a lower part of the block, which has lost its balance, in the slide basis zone. The paper considers the conditions of the new landslide block formation, the beginning of block displacement process, the mechanism of interaction between blocks, the bedrock massif and the landslide body, which consists of earlier displaced landslide blocks. The paper also provides the rationale for the soil strength changes in the process of displacement and its significance in the landslide cycle completing, with comparing the results of theoretical and experimental studies.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):13-20
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Regime of karst and glacial lakes at the carboniferous plateau of Tikhvin Ridge in the Northwest of the Russian platform
Belov K.V., Ignatov P.A., Goryunov E.Y.

Abstract

The studied territory is restricted to the central part of Tikhvin Ridge composed of karstified terrigenous and carbonate deposits of Carboniferous age. The central part of the area is a flat watershed dividing the rivers flowing northwest to Lake Ladoga and those flowing southeast to the Rybinsk water reservoir. The considered territory lies within the Msta River basin subjected to the recent tectonic uplift, forming landforms of Alpine type. Considerable longitudinal sloping of rivers provide intense surface and subsurface runoff (the active hydrodynamic regime). In the considered territory, the lakes are known with their areas changing significantly and quickly enough (months or years). The water in lake basins may disappear or fill them back completely. According to observations, these abrupt decreases and rises in water level do not correlate with seasonal floods, high water and low water periods. The phenomenon of drying and (what is particularly interesting) subsequent filling of lake basins with water is obviously related to the karstic groundwater regime, which is of scientific interest. The up-to-date research data include state geological maps (scale 1:200 000); topographic maps (scale 1:100 000); space images of the free-access Google Planet Earth Internet service, taken in summer and autumn 1984-2016; and weather service data. Cartographic materials were processed in GIS. The analysis of collected data allowed us to distinguish between two types of lakes, i.e., those with insignificant and substantial changes in area with time. Water reservoirs of the first type located on water-permeable moraine Quaternary deposits are classified as glacial. Other lakes overlying immediately Carboniferous deposits, have funnels in the basin bottom and are considered as karstic. The areas of two glacial and three karstic lakes have been measured (by interpreting satellite images) within the central part of the Carboniferous plateau at the Tikhvin Ridge. Variation in the glacial lake areas in the span of 33 years were found to be not crucial, being directly related to annual atmospheric precipitation not correlating with the changing areas of karstic lakes. Karstic lakes reveal 2-, 3- and 12-year-long cycles of significant changes in areas. These changes show decreases and rises in their levels and volumes. They are correlated among all karstic lakes irrespective of the average annual volume of atmospheric precipitation. It points to the significant participation of groundwater in alimentation of karstic lakes belonging to a single karstic water-bearing complex of underlying Carboniferous deposits. Authors relate the recurrent shallowing and filling of karstic lakes to the modern alternating tectonic movements leading to variation in permeability of karstic groundwater-bearing deposits.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):21-29
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Formation and structure of hypergenesis zone in the above-salt layer of the Verkhnekamskoe potassium salt deposit, Perm Krai, Russia
Mamaev Y.A., Yastrebov A.A.

Abstract

The paper describes the formation conditions and factors, as well as the structure and properties of rocks at the unique geological object within the Verknekamskoe potassium salt deposit, i.e., more than 90-m-thick zone of hypergenesis in the above-salt massif of interbedding terrigenous, terrigenous-carbonate and halogen deposits of lower Permian age, which covers the salt horizon of 300-700 m thickness. The geological history of the area is described in brief, which controls its geological and geomorphological structural features. The natural conditions and rock-transforming factors operating for millions of years are discussed. The composition, state and properties of rock in the hypergenesis zone are characterized, including their changes with the depth. This is important for the assessment and prediction of karst development in the considered area, as well as surface deformations and collapses.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):30-37
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Assessment of initial seismic impacts on the northern part of the Barents Sea shelf (Novaya Zemlya region) for the purpose of seismic microzoning in the areas of prospective hydrocarbon mining
Mindel I.G., Trifonov B.A., Kaurkin M.D., Nesynov V.V.

Abstract

In recent years, in connection with the national task of developing the Arctic territories of Russia and the perspective increase in the hydrocarbon mining on the Arctic shelf, more attention is being paid to the study of seismicity in the Barents Sea shelf. The development of the Russian Arctic shelf with the prospect of increasing hydrocarbon mining is a strategically important issue. Research by B.A. Assinovskaya (1990, 1994) and Ya.V. Konechnaya (2015) allowed the authors to estimate the seismic effects for the northern part of the Barents Sea shelf (Novaya Zemlya region). The paper presents the assessment results of the initial seismic impacts that can be used to solve seismic microzoning problems in the areas of oil and gas infrastructure during the economic development of the Arctic territory.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):38-47
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Environment contamination
The background content of heavy metals in the water of small rivers in the Nadym – Pur interfluvial area
Soromotin A.V., Kudryavtsev A.A., Efimova A.A., Gerter O.V., Fefilov N.N.

Abstract

This article considers the problem of the formation of the microelement water composition of the small rivers not directly affected by the oil and gas industrial complex in the Nadym-Pur interstream area. Physicochemical characteristics and ionic composition of the natural water samples are determined by chemical aqueous method, the total content of heavy metals is analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). More than 99% of the sum of all the heavy metal mass with concentration above 0,1 mcg/dm3 is defined by the presence of fourteen metals ranged as following: Fe>>Mn>>Sr>Ba>Zn>Rb>Cu>Co>Ni>V>Ce>Zr>Pb>La. Groups of such metals as manganese and strontium, nickel and cobalt, lead, zinc and copper, vanadium and zirconium, cerium and lanthanum form the concentration сlusters. In comparison to large and average rivers, water samples from small rivers contain higher concentrations of iron and manganese, and lower concentrations of zinc. The Fe and Mn content may vary depending on such characteristics as water color index and water turbidity. The significant exceedance of MACf of Fe and Mn is observed everywhere. The excess of zinc, caused by natural factors is occasionally fixed. The defined variability ranges for the heavy metal contents in water of small rivers located beyond the reach of the oil and gas industrial complexes effects are suggested to consider as modern background regional values of the heavy metal concentrations throughout water-collecting area of Nadym and Pur rivers in Yamalo-Nenets Autonomous Okrug of Tyumen region.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):48-55
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Conditions, consequences and prevention ways of behind-the-casing flow in deep well injection disposal of liquid waste sites
Ponizov A.V., Vereshchagin P.M., Chulkov N.V., Sharaputa M.K., Baidariko E.A.

Abstract

The main detection methods, signs, geotechnical conditions, factors and potential consequences of liquid radioactive waste (LRW) behind-the-casing flow are described in the paper. Based on the modeling results for the real LRW components behind-the-casing flow, the mechanism of behind-the-casing flows evolution in the intervals of wells with increased permeability of cement stone are presented. The concentration of LRW components in these intervals changes significantly in time and depends not only on their current concentration in the waste and the permeability of the rock, but also on the pressure gradient, the direction and absolute value of which are determined by the well operation mode and natural hydrogeological conditions. It is noted that behind-the-casing flows of groundwater and LRW components are formed primary in injection wells, above its filter and top of aquifer used for LRW disposal (operational aquifer). The behind-the-casing flows lead to technogenic changes in the geological environment, which are local in space and time, and reduce the safety of such facilities as deep-level disposal sites for LRW (DDF LRW).

The vertical channel of increased permeability around injection wells and behind-the-casing flows may be prevented by improving the design and construction materials of wells, adjustment of the LRW disposal mode and other methods, including the use of new sealing materials and clarifying technical solutions.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):56-67
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Research methods and techniques
Development of the induced thermokarst model for the remote assessment of natural hazard
Victorov A.S., Orlov T.V., Dorozhko A.L., Zverev A.V.

Abstract

The paper deals with the probabilistic approach to modelling the thermokarst processes induced by linear engineering structures. We have improved the previously published model and have determined the mathematical laws for the two semi-axes of the thermokarst focus (the lengths of the projections on an engineering structure and its perpendicular). The analytically obtained laws should be followed with the validity of the proposed model: the lengths of the projection on the engineering structure and the perpendicular must obey the lognormal distribution; the ratio of the lengths of the projections between them must have a statistically significant correlation and obey the lognormal distribution. The proposed model was tested at five sites in Eastern Siberia. For all sites, the proposed model has confirmed its validity. Thus, the proposed model can be used for remote hazard assessment and risk analysis for linear structures in the permafrost zone.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):68-76
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Prediction of the chrome distribution in subarctic Noyabrsk using co-kriging, generalized regression neural network, multilayer perceptron, and hybrid technics
Buevich A.G., Subbotina I.E., Shichkin A.V., Sergeev A.P., Baglaeva E.M.

Abstract

Combination of geostatistical interpolation (kriging) and machine learning (artificial neural networks, ANN) methods leads to an increase in the accuracy of forecasting. The paper considers the application of residual kriging of an artificial neural network to predicting the spatial contamination of the surface soil layer with chromium (Cr). We reviewed and compared two neural networks: the generalized regression neural network (GRNN) and multilayer perceptron (MLP), as well as the combined method: multilayer perceptron residual kriging (MLPRK). The study is based on the results of the screening of the surface soil layer in the subarctic Noyabrsk, Russia. The models are developed based on computer modeling with minimization of the RMSE. The MLPRK model showed the best prognostic accuracy.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):77-86
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Towards а design of new generation digital seismic seabed seismographs – current state and future outlook
Il’inskiy D.A., Ginzburg A.A., Voronin V.V., Ganzha O.Y., Manukin A.B., Roginskiy K.A.

Abstract

The paper presents the comparative characteristics of self-pop-up digital seabed seismometers that have been developed since the early 2000s. The requirements for the main technical characteristics that should be considered for developing the new-generation of self-pop-up seabed seismometers have been proposed. The microcontroller and reference frequency generator are the key parts for a seabed seismometer design. The paper provides the development results of these key components, which are essential for the seismometer performance (power consumption and functionality).

A draft proposal for seabed seismic exploration project in the Russian sector of the Black Sea solving the current actual geological problems is presented. Implementation of the project will contribute to determination of the crystalline basement depth within the Shatsky ridge and the Tuapse depression; detection of P and S wave velocities in the lower part of sedimentary cover and in the basement, and to the refinement of the Earth’s crust thickness. The extension of regional seabed seismic lines from the Turkish to the Russian sector of the Black Sea will give the scientists a clearer picture of the Earth’s crust structure over the whole east Black Sea basin. The results of seabed studies will verify and improve the results of the Black Sea 2011 towed-streamer survey (with 10 km streamer) on the sedimentary cover structure and the Earth’s crust.

Геоэкология. Инженерная геология. Гидрогеология. Геокриология. 2019;(2):87-101
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