Geological structure and localization of mineralization at the Moryanikho-Merkurikhinskoye ore field

The paper discusses the lithological and facial features of the terrigenous-carbonate (biohermic) ore-bearing geological formation of the Moryanikho-Merkurikhinskoye ore field (Yenisei Ridge), which hosts stratiform lead-zinc deposits in carbonate strata. Ore-hosting lithofacies and their paleostructural position are characterized. Based on the previous studies, as well as the author’s own materials obtained as a result of field work, the main favorable lithological, facial and structural factors for hosting Moryanikhinsky-type stratiform lead-zinc mineralization are defined: the presence of paleodepressions within the shelf zone; development of carbonate rocks – dolomites, stromatolite dolomites and limestones, which are biohermic structures on the slopes of paleo-uplifts; the presence of an admixture of tuffaceous material in terrigenous rock varieties. The influence of tectonic faults on the formation of ore deposits and the morphology of ore bodies is indicated. The main types of ores of the Moryanikho- Merkurikhinsky ore field, as well as their mineral composition are described. The paper discusses the main ore types, as well as their mineral composition typical of the Moryanikho-Merkurikhinskoye ore field. The largest and well-studied lead and zinc stratiform Moryanikhinskoye deposit and Merkurikhinskoye ore occurrence located within the ore field are briefly characterized. The Moryanikhinskoye deposit is a typical example for searching for stratiform deposits of lead and zinc in the carbonate strata of the Angara-Bolshepitskaya mineragenic zone, which is of practical interest in developing predictive prospecting models of deposits and improving the efficiency of prospecting.

Spatial analysis of seasonal patterns in sea surface temperature and salinity distribution in the Black Sea (1992-2017)

Sea water temperature and water salinity one of the most important environmental factors of the marine ecosystems. Both of them plays an important role in forming suitable environment for marine living organisms and have a great impact on species biodiversity. Our goal for this paper was to identify spatial patterns of interannual variations in the salinity and temperature fluctuations to understand possibilities of future change of the Black Sea ecosystem and its impact on fisheries. We used temperature and salinity data from CMEMS for the 1992-2017 time period. All downloaded data was processed by QGIS 3.14 and R 4.0.3. We found that the temperature regime of the Black Sea in different periods of the year is determined by three main factors - the depth of the shelf zone, the influence of river runoff, and water circulation due to currents. The average salinity of the Black Sea waters is 19 ‰, areas with lower salinity are located near the west shore, due to the flows from the largest rivers (Dnieper, Dniester, Danube) bringing a large amount of fresh water to the Black Sea. The area with higher salinity is located in the south- west due to the water exchange of the Black Sea with the saltier Sea of Marmara (∼ 26 ‰) through the Bosphorus. The currents of the Black Sea pick up the salty water of the Sea of Marmara and slowly moving the water column against the clockwise, carry it across the entire Black Sea, thereby increasing its average salinity.

Complex geodynamic indicators for forecasting hydrocarbon deposits in the arctic zone

In the article, in relation to the Arctic zone of the Russian Federation, a new method of forecasting hydrocarbon deposits based on computer geodynamic modelling procedures is considered. It is less expensive compared to field and analytical methods. The approbation of the method on the example of the Laptev Sea shelf zone showed a good interpretability of its results and their compliance with the forecast obtained by other methods. The rationality of using six geodynamic indicators for forecasting: the distributions of vortex structures of the velocity vectors of horizontal shear deformations and vortex structures of normal linear deformations; the values of the velocity vectors of horizontal shear deformations and velocity vectors of horizontal normal linear deformations; the distributions of the anomalous gravitational field in isostatic reduction and the reduced temperature. The sequence of stages in determining the potential of hydrocarbon deposits in the studied territories is described, which is associated with the solution of six interrelated sequential tasks: the choice of local territorial areas of optimal size - the calculation of geodynamic indicators – the allocation of homogeneous territorial clusters – the detailing and improvement of geodynamic indicators – the determination of the potential of oil and gas fields in the cluster – the localization of oil and gas fields in each cluster – construction of a digital forecast map of the location of oil and gas fields in the study area.

Spreading of the semi-arid climate across South Africa

The eastward shift of semi-arid climate across South Africa is studied using satellite assimilated cloud cover, vegetation temperature and potential evaporation 1981–2019, and 21st century coupled model projections. Semi-arid thresholds over the plateau have shifted hundreds of kilometers eastward in the Vaal River catchment for potential evaporation, cloud fraction, and vegetation temperature. Coastal cloudiness has also changed due to sea breezes modified by shelf zone sea temperatures. Processes underlying the spread of semi-arid conditions across South Africa are quantified. Desiccation is related to greater westerly airflow, as the atmospheric boundary layer over the Kalahari preferentially links with the upper-level circulation. Warm dry spells and climate change enhance the meridional temperature gradient and accelerate the sub-tropical jet at both short- and long timescales. According to observations and reanalysis, dry westerlies prevail during the afternoon and induce +0.2 °C/year trends in vegetation temperature over the Highveld during the study period. Coupled model projections show that semi-arid conditions expand eastward from Bloemhof (25.5°E) by 50,000 km2, altering future adaptation strategies.

The exploration of wave processes in the Arctics geological layers in the presence of the ice field.

The Arctic shelf zone is a very important region in our country due to the huge amounts of hydrocarbons, located there. The exploration of this region is difficult because of the presence of lots of various ice constructions, in particular, ice fields. While carrying out the seismic prospecting works, the reflected waves from the ice field contribute much to the seismograms. It sufficiently complicates the process of further interpretation of the seismograms. Only a few works are devoted to modelling the seismic waves spread through the geological layers of the Arctics in the presence of an ice field as this theme is rather new and needs deeper investigation. In this work we present the results of the investigation of the seismic waves spread in models with an ice field for the 3D case using the grid-characteristic method. The modelling results (wave fields of the velocity distribution and seismograms) allow to identify the reflected waves from the ice field from other waves. In addition, we carried out the comparative analysis of the wave fields and seismograms for the 2D model with an ice field on the surface of the calculated area for the problem description from the work of other authors. The results demonstrate a good qualitative coincidence under different approaches to the solution of the problem.

Selection of HR-Strategy in the Location of the Transport-Technological System of Oil Fields in the Russian Arctic

The development of Arctic hydrocarbon resources is in the sphere of interests of many large companies. At the same time, the vast northern territories and polar seas do not have a developed infrastructure that would allow implementing various transport and technological solutions for the development of oil fields. The opportunities for attracting the resources of the Russian Arctic into economic circulation are currently being used to a small extent, which is caused by various factors, both objective and subjective, that were formed at the previous stages of the country's development. This work is devoted to the problem of choosing an HR strategy when placing objects of the transport and technological system of oil fields in the Russian Arctic, taking into account the ecological, economic and socio-economic features of this macroregion. Using the example of oil and gas fields in the coastal-shelf zone of the south-eastern part of the Barents and Kara Seas, the authors consider multivariate forecasts for the formation of a rational scheme for the transportation of hydrocarbons as an integral part of the regional oil and gas complex. The authors assign a special role to the important economic and socio-psychological components associated with the processes of organizing the work of oil workers. At the same time, they come to the conclusion that the shift method of labor organization, adopted by many large mining companies, should not displace, but only complement the traditional methods of attracting personnel to the Arctic oil infrastructure facilities. The use of the combined method of labor organization in the Arctic is the most optimal, allowing to integrate the advantages and localize the disadvantages of other methods of labor organization.

Prospects for development of Vietnam underwater springs

The issues of the relevance of exploration and development of seabed deposits are considered. The article provides information on the history and composition of studies of solid mineral deposits carried out in the South China Sea by scientists of the Democratic Republic of Vietnam. The oceanographic and geological characteristics of the Pacific coast of Vietnam, its shelf and continental slope are given. The conditions that form placer deposits in the exclusive economic zone of Vietnam are given, and their brief description is given. Examples of various placers in the shelf zone, their features are given, and schematic diagrams of occurrence are given. The dependence of the littoral width on the height of the tidal wave and the angle of inclination of the shelf is analyzed. Proposals are given on the possibility of developing alluvial deposits in the littoral zone using dry drilling equipment, the advantages and disadvantages of this technology are stated. The features of the influence of climatic conditions of the Pacific coast of Vietnam on the use of hydromechanized technologies in the development of underwater placers are noted. Emphasis is placed on maintaining the ecological balance in the fields of development and the continuation of further research in the South China Sea.

Nonlinear Model of Coastal Flooding by a Highly Turbulent Tsunami

When a tsunami wave comes from ocean and propagates through the shelf, it is very important to predict several dangerous factors: (a) maximum flooding of the coast, (b) tsunami wave height on the coast, (c) velocity of the tsunami front propagation through the coast, and (d) time of tsunami arriving at a given point in the coast and around it. In this study we study the separate case where the angle of inclination α of the seacoast is equal to zero. A linear solution of this problem is unsatisfactory since it gives an infinite rate of the coastal inundation that means the coast is flooded instantly and without a frontal boundary. In this study, we propose a principally new exact analytical solution of this problem based on nonlinear theory for the reliable recognizing these essential tsunami characteristics. The obtained formulas indicate that the tsunami wave can be stopped (or very strongly eliminated) in the shelf zone until approaching the shoreline. For this aim, it is necessary to artificially raising several dozens of bottom protrusions to the level of the calm water.

The Study of Uranium Accumulation in Marine Bottom Sediments: Effect of Redox Conditions at the Time of Sedimentation

To evaluate the effect of redox conditions at the sedimentation stage on uranium content and U/TOC ratio in marine source rocks, we analyzed the accumulation of uranium in modern marine bottom sediments formed in different redox conditions. The behavior of uranium from bottom sediments formed in oxidizing and sub-oxidizing settings has been studied on the sediments of the Upper Pleistocene–Holocene age accumulated in the coastal area of the White Sea (Kandalaksha Gulf). We studied the content of uranium, Eh, pH, TOC, C, H, N, and S element and isotope compositions and other parameters in two sampled columns of bottom sediments at a depth of 0–2.5 m. The composition of sediments was typical for the shelf zone where marine genesis mixes with the continental run-off. The upper layer of sediments (0–50 cm) were characterized by oxidizing conditions (Eh ~ 400 mV); with the increase in depth, redox conditions changed from oxidizing to reducing (0 ÷ 200 mV). The uranium concentration in the upper layer was 1–1.5 ppm, U/TOC ratio varied in the range of 0.8–1.1 ppmU/%TOC. The uranium content and U/TOC ratio increased up to the values of 2.6 ppm and 1.4 ppmU/%TOC at a depth of 0.5−2.5 m, respectively, but the general content of uranium in the studied environment was close to the values characterizing continental run-off. The results obtained for the White Sea sediments were compared with the sediment of the Black Sea, formed in the anoxic conditions of hydrogen sulfide contamination. In these conditions, the uranium content varied from 10 to 20 ppm. The obtained data were interpreted using thermodynamic modeling of the uranium forms in the seawater at different pH and Eh. This study demonstrated that the change of redox conditions from oxidizing to reducing leads to increased uranium content due to a decrease in uranium’s solubility in water. These results show that oxidation–reduction potential could be one of the most important factors controlling uranium content in black shales formed in the marine environment.

Earthquake on December 12, 2020 in the Anapa zone with Mw=3.8, I0=4-5

The article presents instrumental and macroseismic data on the earthquake on 12.12.2020 at 14:54 with Mw=3.8, h=30 km. The epicenter and parameters of the earthquake were deter-mined using instrumental data from the network of regional seismic stations in the western zone of the North Caucasus of the EGS RAS. This earthquake occurred in the shelf zone of the Eastern Black Sea coast near the resort town of Anapa, in the Anapa seismically active area. This area tectonically is the conjunction of the northern side of the Tuapse trough and the thrust front of the Greater Caucasus. The focal mechanism for the earthquake was calcu-lated. The solution of the focal mechanism was obtained from the polarization in P-waves at 29 seismic stations. From the focal follows the type of source up thrust-thrust movement. The GS RAS organized a macroseismic survey in the Anapa and Novorossiysk regions on the “VKontakte” social network a day after the earthquake. According to the results of the study, 144 respondents in 15 settlements in 7 days were interviewing. The maximum observed in-tensity was I=4-5 points in Su-Psekh and Varvarovka according to the results of the macro-seismic survey, a map of the distribution of intensity points was create. The SEISAN software package calculated the spectral parameters of the source: seismic moment, corner frequency, spectral density level and spectral magnitude Mw.