Four regions of high natural radioactivity were selected to assess radionuclide levels in rocks and soils, ambient radiation doses, radon exhalation from the ground, and radon concentrations in the air. The regions have different geochemical characteristics and radioactivity levels, which modulate the radiation exposure of local populations. Combining radiometric data with data from regional health statistics on non-infectious diseases, a statistically significant positive correlation was found between radiation exposure and the incidence of cancer and birth defects. Although this is a preliminary and prospective study, the empirical evidence gathered in this paper indicated increased the incidence of some diseases in relationship with the natural radiation background. It is suggested that further research, including epidemiological studies and direct determination of radiation exposures in regions with a high natural radiation background, is needed and justified.
The analysis of altimetric data in combination with bathymetry and gravimetry materials in the north-eastern and southern sectors of the Pacific Ocean, as well as detailed data on the underwater relief, the structure of the sedimentary cover, the composition and absolute age of basalts obtained within the area of domestic geological exploration for ferromanganese nodules (the Clarion-Clipperton zone) is carried out. Structural trends formed by local cone-shaped local structures of presumably volcanic nature, grouped along transform faults belonging to various stages of the kinematics of the Pacific Plate, have been traced in the structure of the oceanic lithosphere at various scale levels. The first trend corresponds to the extension of the fault system corresponding to the spreading system on the crest of the East Pacific rise before the restructuring of its planned geometry in the Paleocene-Eocene, the second coincides with their extension after the change in the relative movement of the Pacific Plate. The trends are characterized by planned disagreement, and an increase in the number of seamounts is observed in the areas of their intersection. Within the area of detailed studies, obvious signs of volcanic-tectonic activity were revealed: high dissection of the underwater relief, hills of different heights with steep slopes, whose volcanic nature is confirmed by differentiated basalts raised from their slopes, the absolute age of which indicates the multistage outpourings that occurred in an intraplate environment. The angular velocity of rotation of the spreading axis and the linear velocity of its advance with changes in the kinematics of the Pacific plate are estimated and possible reasons for changes in its relative motion are considered. An improved scheme of adaptation of the spreading zone to a change in the direction of relative plate movement is proposed, acc0ording to which an essential factor of intraplate volcanic-tectonic activity is the relaxation of stresses in the plate caused by external influence on it.
The study describes the developed cloud web service for multidimensional processing of quantitative data for solving a wide class of scientific geological tasks. The computing node “Multidimensional methods of data analysis” provides processing of tabular data using various methods of modern data analysis and allows to set their parameters and visualize the results. The node includes wide range of methods such as data preprocessing, descriptive statistics, cluster analysis, factor analysis, correlation analysis, regression analysis. Computing node “Multidimensional methods of data analysis” is a part of Computational analytical geological environment of State Geological Museum of RAS and is integrated with its services. At the same time, the computing node is an independent cloud web service which implements REST API for interaction with it. This allows a wide range of users to access multidimensional data analysis methods located on a computing node and provides capabilities of its integration into information systems as a thirdparty application for processing tabular data.
In 1990, the Sopcheozero Cr deposit was discovered in the Monchegorsk Paleoproterozoic layered mafic-ultramafic layered intrusion (Monchepluton). This stratiform early-magmatic deposit occurs in the middle part of the Dunite Block, which is a member of the Monchepluton layered series. The Cr2O3 average-weighted content in ordinary and rich ores of the deposit is 16.65 and 38.76 wt.%, respectively, at gradually changing concentrations within the rich, ordinary and poor ore types and ore body in general. The ores of the Sopcheozero deposit, having a ratio of Cr2O3/FeOtotal = 0.9–1.7, can serve as raw materials for the refractory and chemical industries. The ore Cr-spinel (magnochromite and magnoalumochromite) is associated with highly magnesian olivine (96–98 Fo) rich in Ni (0.4–1.1 wt.%). It confirms a low S content in the melt and complies with the low oxygen fugacity. The coexisting Cr-spinel-olivine pairs crystallized at temperatures from 1258 to 1163 °C, with accessory Cr-spinel crystallizing at relatively low, while ore Cr-spinel at higher temperatures. The host rock and ore distinguish with widespread plastic deformations of olivine at the postcrystallization phase under conditions of high temperature (above 400 °C) and pressure (5 kbar). At the post magmatic Svecofennian stage (1.84 Ga), the deposit, jointly with the Monchepluton, was subject to diverse tectonic deformations.
An assessment of uranium contents and distribution in drinking water limescale has been conducted in the Republic of Bashkortostan (RB), Russia. A total of 515 limescale samples from 262 settlements of the RB were analyzed. The spread of U concentration values in limescale samples ranged from 0.01 to 61.0 μg/g. Elevated U concentrations in the West of the RB corresponded with the horsts of the granite-gneiss crystalline basement of the South-Tatar Dome and their Eastern slopes, the areas with the Lower Permian red beds and the oil and gas fields. The U migration from the granite-gneiss basement is attributed to the tectonic factor and hydrocarbons movement. Elevated concentrations of U within the South of the RB are associated primarily with the deposits of the Southern Ural brown coal. The Bashkir Trans-Urals anomalies are mainly associated with Lower Paleozoic eclogite complex, Devonian and Carboniferous volcanic-sedimentary, carbonate, intrusive formations, as well as the Jurassic cover of terrigenous marine sediments. The negative anomalies of the spatial distribution of U are located in the area of the Ufa plateau mainly composed of limestone.
The author, Dr. Lazar Kogan, who dedicated the previous article to the anniversary of geophysicist Professor Yuri Neprochnov, will have anniversary on his own – he turn 85 years on September 12, 2020. He, like Yuri Neprochnov, was born in Tashkent in 1935, where he graduated from high school in 1953. After school, on the advice his older friend of Yuri Neprochnov, Kogan decided to pursue profession of geological science, and he entered Geological Department of Tashkent Polytechnic Institute, which he graduated in 1958 with the qualification of a mining engineer - geophysicist. In 1967, he completes his qualification work and receives a Ph.D. In 1986, he defends his dissertation for the degree of Doctor of Geological and Mineralogical Sciences at the All-Union Research Institute of Oceanic Geology, specializing in seismic profiling of deep geological layers. From 1958 to 2015 worked as a marine geophysicist at the seas and World Ocean and since 2015, he works, as consultant is seismic geological surveillance. During his scientific career, Dr. Kogan participated in more than 40 scientific expeditions, some of which he directed himself. He published about 150 scientific works and 7 monographs.
The purpose of the article is to describe the experience of assistance provided by the State Geological Museum of RAS named after V.I. Vernadsky for teachers and teachers of higher educational institutions, as well as a discussion of the problems arising in this direction. The assistance is based on digital technologies and includes various projects: teleconference, broadcast lectures online, video tours of the museum, work with children in remote access. The organization of work with the teaching community is carried out by the Interuniversity Academic Center for Navigation in the specialties of the mining and geological profile, which brings together museum specialists and leading raw materials higher educational institutions. It is noted that a new form of museum work and the interaction of the museum and the teaching community has revealed certain new problems in this interaction. Their reasons are examined, and it is also emphasized that their elimination will solve the very urgent problem of the wide use of the wealth of Russian museums of various profiles in the work of teachers and teachers of institutes and universities.
Изученные образцы слюд из гранитных пегматитов копей Мокруша и Министерская Мурзинского массива на Среднем Урале представлены полилитионитом, соколоваитом, трилитионитом, Li-содержащими мусковитом и промежуточным членом ряда аннит–флогопит. В светлых слюдах из обеих копей отмечены нехарактерные для них хром и магний, что свидетельствует о контаминации пегматитов веществом вмещающих пород. Низкие значения отношения K/Rb и отношение Ta/Nb определяют высокую степень дифференциации пегматитов из обеих копей. Mica samples from granitic pegmatites of Mokrusha and Ministerskaya mines, Murzinka pluton, Central Urals are polylithionite, sokolovaite, trilithionite, Li-bearing muscovite, and annite–phlogopite series. Chromium and magnesium, uncommon elements for light mica are detected in samples from both mines, indicates host-rock contamination of pegmatites. The low values K/Rb ratio and Ta/Nb ratio define a very high degree of pegmatite differentiation of both mines.
Ample geologic and geophysical data provide the basis for distinguishing the 102–104° E geodivider in the North, Central and South Asia. The geodivider’s central part is confirmed by the data on seismicity, seismically active faults and the modern crust block structure. These data and historical and instrumentally identified earthquake epicenters were used for a more correct definition of the block boundaries and interblock zones in the central part of the geodivider and in its wings. Seismic energy is considerably increased (to 1011–1016 J) in the eastern part of the geodivider’s western wing, and rarely increased directly in the geodivider itself. Near the geodivider, a seismic energy increase is detected east of it only at the western border of the South-Eastern China Block. The authors analyzed deep seismic sections and constructed energy dissipation graphs along transects crossing the geodivider and its western wing. The analysis and the graphs show the predomination of left-lateral NW-striking slips in the north, thrusts to the east and southeast in the center, and right-lateral NE-striking slips in the south. The total seismic energy increases constantly to the west. In the central and northern segments of the geodivider’s central part and west of it, horizontal blocks displacements cause a direct influence on seismicity level increasing and changes in geodynamic regimes within the investigated territory of Central Asia. Changes in the horizontal displacement vector are accompanied by the change of tectonic strain regimes. Increased heat flow values to the east from the geodivider within the East Asian transit zone are probably related to the change of the geodynamic regimes in the same direction under the influence of the submerged Pacific slab. The data obtained by the Chinese and Russian researchers confirm delamination (stratification) processes in the Southeast Tibet crust during its interaction with the colder and thicker lithosphere of Southeast China, and displacement of its upper layers to the southeast and south, as we supposed in our earlier publications.
The distributions of niobium mineral deposits and their resources on the geological time scale are analyzed. The sampling list includes 45 mineral deposits with their individual resources estimated not less than 100 Kt of Nb2О5. The classification of deposits used includes three types, namely, alkaligranitic, foidic, and carbonatitic. The geohistorical variability in niobium metallogeny is presented through comparison of supercontinent cycles. To date, no deposits belonging to the Kenoran cycle, which are of interest for the targeted extraction of niobium, have been identified. The Columbian cycle is the oldest among the significant cycles in niobium metallogeny, but its resources are relatively small. The most significant resources of nio-bium are related to alkaline igneous complexes of the Rodinian, Pangean, and Amasian cycles. The resources of carbonatitic deposits are sharply predominant among all resources generated in the cycles of geological history considered. A consistent increase in the share of resources of such deposits is established through the chronological sequence of supercontinent cycles. The maximum amount of resources of the foidic type is concentrated in the deposits of the Rodinian cycle, while a much smaller amount is in those of the Columbian and Pangean cycles, and no foidic deposits have been identified in the Amasian cycle. The alkaligranitic type demonstrates the smallest fluctuations in niobium resources among the cycles compared; however, its relative contribution to the total resources of all cycles is very small, except for the low-productive Columbian cycle. Despite the close relationships between niobium and tantalum in the mineral-forming processes, these elements do not always show mutually comparable ore concentrations in terms of economic value in the same deposits. Such a coincidence chiefly takes place in mineral deposits of the foidic and alkaligranitic types, which are not yet of great importance in real extraction of both niobium and tantalum. In terms of economic value, carbonatites are almost always specialized exclusively in niobium, while rare-metal pegmatites and granites are specialized in tantalum. These types of mineral deposits are formed in completely different geodynamic environments from magmas of contrasting composition that originated in different lithospheric layers. Therefore, the revealed differences in the historical metallogeny of these two metals have a logical explanation.
The residual flow effect of a geothermal loop is the flow of fluid from a geothermal reservoir through production well, heat exchanger, and injection well after switching off the pumping equipment. Earlier, this phenomenon was mentioned in the literature for the possibility of reinjection of the cooled fluid without pressure, but with no detailed consideration. After observing this effect at the Khankala experimental geothermal plant, the authors have investigated the physics of the effect and the possibility of its use in energy production.
The experience of educational work with the younger generation in order to awaken its interest in the professions of geologist and miner is considered. Innovative approaches are developed and implemented in three areas: practical works with geological and paleontological samples; conducting «geological expeditions», where children acquire the skills of a field geologist, get acquainted with the objects of the mining industry and carry out the formation of personal geological collections; the study of geological processes and structures through specialized excursions in the Museums expositions. The efficiency of the applied methods is analyzed, the ways of their further development and improvement are discussed. Many tasks are solved in the framework of projects and programs of the Interuniversity Academic center of navigation in the field of mining and geological profile. The experience gained may be of interest to the other natural science museums, as well as to organizations that carry out educational work with the younger generation.
The global distribution of tantalum deposits and their resources on the geological time scale is analyzed. The analysis is based on the data for 65 deposits of the world with a resource estimate from 2000 t of Ta2O5, which are classified into five types: pegmatitic, granitic, alkaligranitic, foidic, and carbonatitic. Placers and ore-bearing weathering crusts are taken into account with their bedrock sources. The variable features of the global metallogeny of tantalum are represented based on the comparison of the supercontinent cycle. It is established that the most significant resources in terms of quantity are confined in the deposits of the Rodinian cycle, among which the foidic type objects are fully dominant. Then, the descending order for the total resources is the Pangean and Columbian cycles, in which the main shares in the resources belong to the deposits of the alkaligranitic and foidic types. The Kenoran cycle, which lags behind them in its quantitative estimate, stands out in tantalum metallogeny by a monotype nature: only pegmatitic objects have created its resource potential. The current Amasian cycle is in the last place with respect to the total quantity of tantalum resources, which is explained to a great extent by its incompleteness. The resources of this cycle are distributed between the objects of the alkaligranitic, granitic, and pegmatitic types in comparable shares. It is noted that, due to their mineralogical features, the deposits of pegmatitic and granitic types make it possible to obtain the highest-quality concentrates and they are, therefore, of prime interest for tantalum extraction. The deposits of the pegmatitic types are known in all the cycles, while the deposits of the granitic type are known only in the Pangean and Amasian cycles. In total, they contain only one fifth of the estimated tantalum resources, and their major share accounts for the Kenoran and Pangean cycles. (https://rdcu.be/b1gRq)
The research results were received from studying the Pechenga ore-bearing Paleoproterozoic structure, which is located on the northwestern part of the Kola region. The U–Th–Pb zircon age was determined by Secondary Ion Mass Spectrometry (SIMS) on the Sensitive High-Resolution Ion microprobe (SHRIMP-II) spectrometer and Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICPMS) on the ThermoQuest Finnigan MAT Neptune instrument. Basalt conglomerates of the Televi Formation, red gritstones of the Luchlompolo Formation, and high-siliceous turbidites from the middle part of the Matert Formation were tested. On the U–Pb concordia diagram, the part of analytical points for zircon from conglomerates are approximated by the discordia with a top intercept at 2792 ± 7 Ma. All zircon grains from gritstone are located on the concordia. Most of the values of their ages lie within 2700–2820 Ma, and the lesser part of the age values lies within 2840–3000 Ma. Single grains have an age from 3037 ± 4 Ma to 3698 ± 8 Ma. The concordant value of the ²⁰⁷Pb/²⁰⁶Pb age, which is 2640 ± 16 Ma, was established for turbidite zircon. Rocks of the basement at the northern rim of the Pechenga structure: gneisses of the Kirkenes, Varanger, and Svanvik complexes (2715, 2803, and 2825 Ma) and high-aluminous gneisses (2798–2830 Ma) were sources of zircon for conglomerates and gritstones. Granitoids from the southern flank of the structure were sources of zircon for turbidites. The predominant role of the zircon group with an age of 2.7 Ga proves the global increment of the continental crust during this period. The ancient age of zircon (3.0–3.7 Ga) of red-colored gritstones is related to deeper erosion of the basement and exposure of the Eoarchaean and Mezoarchaean rocks at the northern rim during the period of the first global “Oxygen revolution” (2.4–2.3 Ga).
Niobium metallogeny over the course of geological history has been considered on the basis of data from 45 largest deposits in the world belonging to any of three metallogenic types: alkaligranitic, foidic, and carbonatitic. The deposits were formed under variable intensity from the Middle Paleoproterozoic to the Cenozoic. The greatest resources of niobium are accumulated in the deposits formed during the Rodinian, Pangean, and Amasian supercontinent cycles. These cycles are characterized by the prevalence of deposits associated with carbonatite complexes. (full text - https://rdcu.be/bPqhq)
This paper reports on lithium metallogeny in geological time. The geochronological analysis was conducted on the basis of data on 71 lithium deposits distributed globally. These deposits contain almost all Li resources, which are industrially significant and of potential interest in terms of the economy. It was established that these deposits were formed in different geological epochs, from the Late Mesoarchean to the Holocene. The distribution of their resources on the scale of geological time is distinctly discrete. In the Kenoran, Columbian, and Rodinian supercontinent cycles, only pegmatite deposits of lithium were formed. In the Pangean cycle, the main resources are also attributed to pegmatite deposits, but some of them are concentrated in lithium–fluorine rare-metal granites. In the incomplete Amasian cycle, salars of geodynamically active areas play a main role in the resource base; the epithermal stratiform deposits, pegmatites, and lithium-fluorine granites are of much less significance.
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