(Lithosphere)
Published by The Institute of Geological Sciences of the National Academy of Sciences of Belarus & The Belarusian Geological Society, Minsk, Republic of Belarus
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LITASFERA (Lithosphere) Published by The Institute of Geological Sciences of the National Academy of Sciences of Belarus & The Belarusian Geological Society, Minsk, Republic of Belarus |
Abstract: This paper deals with the creation of the National geophysical monitoring system in Belarus. The necessity of creating such a system is confirmed by the results of integrated interpretation of geophysical observation and survey records, DSS data, geological and cartographical evidences. These results have permitted the following conclusions. Intensive deep processes in the tectonosphere of Belarus result in seismic activity and slow vertical and horizontal movements of the Earth's surface. These processes, deep inhomogeneities of the lithosphere and some processes in the outer space cause anomalies of geophysical fields. Some kinds of human activity may also influence geophysical fields. On the other hand, temporal and spatial variations of geophysical fields may influence some biological and technical systems, violate their normal work or, on the contrary, promote their development. It is known that geophysical fields and modern tectonic and physical processes are the most active in the zones of deep faults in the Earth's crust and upper mantle. The negative impact of geophysical fields on technical and biological systems and a great number of important industrial objects in the territory of Belarus must be taken into account when any kind of activity is planned in this area. Permanent control over the geophysical fields dynamics is necessary. The only solution of this problem is the creation of the National geophysical monitoring system in Belarus. From our point of view, the system of "Geophysical monitoring" must have two main control levels. The sub-system of the first level is the regional monitoring system. Its aim is to control the dynamics of geophysical fields and tectonic processes throughout the territory of Belarus. The main function of the second level sub-system (local level system) is to control the dynamics of geophysical fields, local tectonic processes and slow horizontal and vertical movements of the Earth's surface immediately at the most important industrial objects and construction sites. The control over the temporal variations of geophysical fields must be performed using a net of stationary functioning geophysical observatories and repeated observations of geophysical fields. The control over the slow vertical and horizontal movements of the Earth's surface should be carried out by traditional geodetic methods. The system of "Geophysical monitoring" must also solve the problem of seismic zoning of the territory of Belarus and detecting areas dangerous for construction of important objects. It must supply the authorities of Belarus with the information about the most significant seismic events in the terrirory of Belarus and ajacent areas of Eastern and Western Europe. In our opinion, the work on the technical project of "Geophysical monitoring system" has to be carried out in three stages. The first stage suggests the develop ment of the main concept of geophysical monitoring that takes into account the location and main characteristics of ecologic-geophysical objects in the territory of Belarus. The second stage is to work out an optimum national network of geophysical observatories and to determine the location of sites where the control over dynamics of geophysical fields and slow vertical and horizontal movements of the Earth's surface in the territory of Belarus must be performed. The third stage envisages working out the concept of local geophysical monitoring of the most important objects (for example, monitoring of the Soligorsk potassium region). In our opinion, the creation of "Geophysical monitoring system" may be based on the work of the Laboratory of Physics of the Earth, the Laboratory of Seismology and the Experimental Seismic Group of the Institute of Geological Sciences of the National Academy of Sciences of Belarus. They have all the necessary conditions for the efficient work: highly skilled personnel, up-to-date geophysical equipment and computer facilities and a wealth of experience in this field of research.
Zinovenko G.V.
Ancient zones of pericratonal subsidences as parts of marginal systems of the East European Craton. pp. 24--33
Abstract: The paper briefly describes the pericratonal subsidence zones and (or) passive continental borderlands of the East European Craton that are parts of the Cis-Appala-chiàn -- British-Scandinavian, Cis-Ural, Cis-Mugodzhary marginal systems, as well as of a marginal system situated at the boundary between Polish-German Caledonides and the old platform. Passive continental borderlands had been formed during the oceanic stage of the marginal systems evolution. They differ in their formation age (Caledonian and Caledonian-Hercynian) and duration (160 mln. yrs. and 190 to 200 mln. yrs.), in intensity and extent of tectonic processes proceeding within their limits, in their oil and gas potential. Their evolution followed the pattern of recent Atlantic passive continental borderlands, or those situated along narrow incipient oceans. The main destinguishing features of marginal systems had been generally formed at the orogenic stage of their evolution.
Vysotsky E.A.
The stages of the Potassium accumulation in the Earth's history. pp. 33--42
Abstract: In the history of the formation of the Earth's sedimentary mantle fifteen stages of potassium accumulation have been revealed: 1) the Early Cambrian, 2) the Late Silurian, 3) the Middle Devonian, 4) the Late Devonian, 5) the Early Carboniferous, 6) the Middle Carboniferous, 7) the Early Permian, 8) the Late Perminan, 9) the Late Triassic, 10) the Late Jurassic, 11) the Early Cretaceous, 12) the Late Cretaceous, 13) the Eocene-Oligocene, 14) the Miocene, 15) the Pliocene-Quaternary. There were stages of the grandiose sedimentation (the Early Permian and the Late Permian) and the stages when comparatively small volumes of potassic salt were formed. The characteristic feature was an abrupt decrease of the intensity and scales of the potassium accumulation from Paleozoic to the Mesozoic: during the Paleozoic 95.3% of potassic salts were accumulated, during the Mesozoic -- 4.5%, and during the Cenozoic -- 0.2%. In the Phanerozoic two parallel branches of the potassic accumulation were distinguished: the chloride and the sulphate one. The chloridic branch was related to the formation of potassic salt containing deposits composed mainly of sylvinite and carnallite rocks, while the sulphate branch was connected with the sedimentation of hydrated and not hydrated chlorides and sulphates of potassium, magnesium and calcium. The arising of potassic salts accumulated in evaporite basins was closely connected with the general course of tectonic, climatic and palaeogeographic change, as well as with the alternation of sea transgressions and regressions. The potassic salt sedimentation coincided with geocratic periods of the Earth's evolution when 95% of the total volume of potassic salts was formed.
Abstract: The palynological study of the Oligocene continental deposits of Belarus, carried out in the last years has revealed five successive palynocomplexes, each characterized by definite peculiarities, and five phases of the vegetation development. The complex Stradubka I (str I) is distinguished by the domination of coniferous species pollen (93--97%), mainly of Pinus subgenus Haploxylon, Podocarpus and Cathaya; presence of angiosperms and single pollen grains of herbaceous plants and spores. The complex Stradubka II (str II) is characterized by the predominance of coniferous pollen (55--87%), among them -- Pinus subgenus Haploxylon; high content of Podocarpus (up to 22%), Cathaya (up to 14%), Taxodiaceae and Cupressaceae (in sum up to 25%); considerable participation of Sciadopitys (up to 7%); higher quantity of angi-osperm pollen, especially Anacardiaceae (Rhus) -- up to 23%, Engelhardtia (up to 5.5%) and formal genera (up to 13%). The complex Stradubka III (str III) is distinguished by the domination of coniferous plants (94--98% of pollen), mainly Pinus subgenus Haploxylon, Podocarpus and Cathaya; inconsiderable participation of pollen of herbaceous plants and spores. The complex Krupejka I (kr I) is characterized by the predominance of coniferous pollen (60--80%), firstly Pinus subgenus Haploxylon; high percentage of Taxodiaceae (up to 25%), Podocarpus (up to ), Cupressaceae (up to 13%), Sciadopitys (up to 8%), Cathaya (up to 3%); considerable content of formal genera pollen (up to 16%); participation of Nyssa, Rhus, Myrica, Engelhardtia, Cyrillaceae-Clethraceae, Liquidambar pollen; increase of Betula and Alnus; small quantity of pollen of Ulmus, Zelkova, Corylus, Quercus, Fagus, Juglans, Carya, Pterocarya, Ilex, Symplocos, Sapotaceae, Sterculiaceae, etc.; few pollen grains of herbaceous plants and spores. The complex Krupejka II (kr II) differs by the predominance of coniferous pollen, mainly Taxodiaceae (up to 60%); decrease of Podocarpus (up to 8%) in comparison with its amount in the previous phase; higher amount of Myrica, Rhus, Corylus and formal genera, appearance of Itea. The Orsha complex revealed in the northern part of Belarus typically shows the domination of coniferous pollen, mainly Pinus, Taxodiaceae, Sciadopitys, pollen of Fagus, Rhus, Ilex, Myrica, Betula and representatives of formal genera among angiosperms. The variation of the systematic composition and frequency of individual components testifies to the repeated climatic changes and allows the reconstruction of stages of the flora and vegetation development at the end of the Oligocene period.
Baltrunas V.A.
Multinomiality -- specific property of pleistocene tills in Lithuania. pp. 58--64
Abstract: Multinomiality of stratigraphically contemporaneous glacial rock mass sediments is noted from data of granulometric, mineralogical, geochemical, geophysical and other analytical studies and sometimes from macroscopically noticeable features (colour, cleavage, bedding, etc.). The multinomiality is confirmed by D.Rodionov's statistical method for linearly ordered sets of differentiation. It should be noted that statistically determined boundaries (particularly their significance) on the grounds of different analytical investigations do not always coincide. The following four causes of tills multinomiality are considered to be most frequent: 1 -- repeated (phase, oscillation) sedimentation of glacial deposits during the cycle of one glaciation in the melted away proximal part of glacier, as well as in its distal part; 2 -- scaly motion of ice mass in the lower part of the glacier marginal zone and associated removal of detached blocks of rocks of another genesis and age, their transportation and assimilation; 3 -- expansion of genotypes, varieties and facies (basal, ground, ablation, marginal and other tills) of glacial sediments; 4 -- post-sedimentation processes (solifluction, gravitation, wash out of carbonates, reduction, weathering, etc.). An identification of the tills of the last glacier recession stages, separation of elementary ground till, pecularities of blocks (glaciotectonites) expansion and process of their assimilation, signs of buried crust of weathering of Merkine (Eemign, Mikulino) Interglacial are discussed on the grounds of data obtained from specific geological objects.
Abramenko V.I., Zinovenko G.V.
Preteilobite Lower-Cambrian deposits of nort western Belarus and adjacent territories. pp. 64--73
Abstract: To reconstruct paleogeographical conditions that had existed within the territiry of Belarus in the Early Cambrian, and to correlate principal geological events of that time in the nortwestern and southwestern parts of the Republic, where Cambrian deposits are preserved, detailed lithological and mineralogical investigations have been carried out in deposits found in northwestern Belarus and adjacent Lithuania and Latvia. Principal laws governing the distribution of the main rock types, rock-forming and authigenetic minerals, that depend on the facies conditions, have been established. The results of these investigations have served as a basis for a etailed lithological and paleogeograhical map, where the facies fields have been distinguished. These maps suggest that the asymmetric structure of the paleotrough of the northeastern strike, where sediments had been accumulated within that territory, shows the synsedimentary nature. There are more impressive evidences of the existence of an entire sea basin, which had connected the territories of the northwestern and southwestern Belarus.
Levych N.N., Samodurov V.P.
Composition of garnets from diatreme rocks of the Zhlobin Field. pp. 74--83
Abstract: The types of garnets from the Zhlobin field diatreme rocks and xenoliths are described. Several types of garnets have been distinguished on the basis of microprobe analyses and petrographic data. It is shown that the colour of garnets does not strongly depend on their chemical composition. Nevertheless the colourthe garnets may be taken into account when analysing the pyrope component. It is shown, that the colouring of garnets depends on the presence of high amounts of ferrous iron components, presence of chromium and manganese oxides. The grossular-almandine-pyrope and andradite-almandine-pyrope types prevail among investigated garnets from diatreme rocks and xenoliths. In a lesser quantities Grossuar-pyrope-almandine type of garnets is less common. Andradite-pyrope-almandine, cocharite-andradite-pyrope, andradite-cocharite-pyrope, almandine-andradite-pyrope and grossular-andradit-pyrope types with different colouring occur less often. It is underlined that garnets from Nizhevskaya 674 diatreme are the most interest ing ones as indicators of diamond-bearing rocks. They are high in pyrope component (58.3--63.4%), relatively low in ferriferrous component (13.3--15.9%) and low in calcium oxide (0.9--2.1%).
Goomen A.M., Pinchuk A.P., Kissin I.S.
Investigation of recent geodynamic processes in the Pripyat Trough with the precision groundwater level measurement method. pp. 83--94
Abstract: The paper presents the data of observations of groundwater level fluctuations in wells located in geodynamically active fault zones of the Pripyat Trough, where the amplitudes of the recent vertical surface movements were as high as 15--20 mm per year, and the geomagnetic and gravitation field parameters varied, respectively, from 10 to 12 nTl and from 0.15 to 0.2 mGal during the first month. It was suggested that such active deformation processes are reflected in the groundwater level regime. Observations of groundwater level fluctuations were carried out in artesian wells with precise gages providing an accuracy about 0.5 mm. The problem of revealing hydrogeodynamic åffects caused by the stress-strain field changes was solved by the study and elimination of the following impedimental factors: hydrologic and meteorologic factors, as well as barometric variations and earth tides. Some general features of the groundwater regime have been studied and the componånts of the water level variation of different duration (hours-days-months) and amplitudes (from 1 to several tens of cm) due to tectonic deformation processes have been revealed. Their deformation nature was confirmed by pecularities of the Earth's surface recent movements, as well as by changes of barometric and tidal efficiency parameters. As it is known, both parameters depend on the aquifer elastic and capacitive properties and, therefore, are very sensitive to reconstructions of the stress-strain field. The results obtained evidently show the potentialities of the hydrogeodynamic method for studying the deformation processes. In addition to a complex of geodetic and geophysical methods, the hydrogeodynamic observations extend the capabilities of geodynamic investigations.
Paliyenko V.P.
Neotectonically Active Fractures in the Territory of the Ukraine. pp. 94--100
Abstract: The paper presents the diagnostic evidences and criteria of determination of neotectonically active fractures in the territory of the Ukraine. Spatial regularities of variation of the velocity gradients of neotectonic and contemporary crustal movements which are the main indicators of activation along fractures are characterized. Specific features of different regimes of contemporary movements along fractures are revealed.
Sim L.A.
Neotectonic stress fields of the East European Platform (EEP) and adjacent structures. pp. 100--107
Abstract: Recent and neotectonic stress fields of the platform structures in Europe have not been adequately studied. The existed schemes of the EEP neotectonic stress fields are based on the generalization of isolated studies carried out in different parts of the platform (Guschenko O.I., 1979, Nikolayev P.N., 1992, etc.). The study of the stress fields of such immense heterogeneities of the Earth's crust as the EEP, young West European and Scythian plates and Timan-Pechora plate with Baikalian basement is a vital problem. Simulation results and visual conclusions on possible distribution of Alpine tectonic stress fields within the above structures underline the importance of this problem.The World Stress map (Zobak M.L., et al., 1992) shows only isolated instrumental measurements within the platforms in Europe. The sole exception is the western part of the Baltic Shield, which was studied using both instrumental measurements of recent stress fields and earthquake focal mechanisms. In general, WNW-oriented subhorizontal recent stress fields are typcal for this part of the Baltic Shield. The purpose of the present study was to investigate neotectonic stress fields of the EEP and adjacent structures in order to compile the first map of neotectonic stress fields of the above territory (scale 1:2,500,000) and to estimate possible influence of global tectogenesis on intraplate tectonics.
Sliaupa S.
Major neotectonically active linear fault zones in Lithuania Engl. 108--115
Abstract: Regional neotectonically active linear zones distinguished in the territory of Lithuania represent the principal structural framework that control the general pattern of neotectonic movements. These linear structures are related, as a rule, to the major tectonic zones of the crystalline basement that were established in Early Precambrian time. These are commonly wide fault zones of the basement and are represented as wide neotectonically active linear zones (NALZ). The structural styles of the major NALZ are quite different and mirror the main features of their deep structure.
Matoshko A.V.
Tectonic features of the quaternary strata structure in the middle Dnieper region. pp. 115--124
Abstract: Quaternary tectonic pattern of the Middle Dnieper region is interpreted on the basis of integrated analysis of the Quaternary deposit base hypsometrical map and the map of their thickness. It comprises the following major structures: inherited swell-like uplifts of the Ukrainian Shield and Voronezh Anteclise, recent Middle Dnieper Trough, transitional zones between them, as well as local structures forming relatively independent network. In Quaternary time this territory developed against the background of pulsating neotectonic elevations, that showed themselves in various evidences.
Chernjakhovsky A.B., Grishko A.I., Shits V.A., Ilkevich G.I., Beljasov A.V.
The potential of the Belarusian Anteclise for building and facing stones. pp. 124--129
Abstract: Rocks of the crystalline basement of the Belarusian Anteclise that occur in a depth range of 80 to 130 m are considered as natural building stone suitable for crushed stone making. These rocks are represented by granite-gneiss, granite, diorite, magmatite and hyperbasite of the Archean and Proterozoic ages. Building stone shows low cracking, considerable strength, conforms to the safety radiation level and occurs under adequate hydrogeological conditions. Promising areas have been found in the (Bobovnja, Pukhovichy, Staritsy regions), their probable reserves being estimated at 23.220; 1.347 and 8.730 million m3, respectively, with a mining depth of 200 m.
Abstract: The microelement contents of minerals from the main rock types of the gneiss-migmatitic complexes of the crystalline basement of Belarus have been established to vary over a wide range. They depend on the following factors: geochemical specialization of primary premetamorphic rocks, nature of paragenetic associations of minerals, conditions of the crystallization, etc. Average microelement content of rock-forming, ore and some accessory minerals (as well as of some minor minerals) are given. These are regional clarkes for rocks of the granulitic, amphibolite-gneissic, schist-amphibolite-gneissic, blastomylonitic and migmatite-granite-gneissic metamorphic complexes. Some general depletion of minerals from the Early Precambrian rocks of Belarus in microelements of the siderophile and partially lithophile associations in comparison with those from the others regions has been revealed. The average element contents (the regional clarkes) of intermediate and acidic rocks of the above complexes are presented. The comparison of the geochemistry of minerals and rocks has established that geochemical characteristics of rock-forming minerals is the main factor, which dictates the geochemical specialization of metamorphic rocks.
Onoshko M.P.
Geochemical information content of Nitrogen in studying Holocene sediments. pp. 140--150
Abstract: The evolution of the Belarusian Poozerje lakes in the Holocene has been paleogeochemically reconstructed using an index of "nitrogen content of organic material". The nitrogen content has been established to increase in lithological types of sediments in (%): sand (0.07) -- clay (0.39) -- marl (0.47); sandy silt (0.27) -- clayey silt (0.48); silicious sapropels (1.15) thin detrital sapropel (2.41) -- course detrital sapropel (0.74). The maximum accumulation of nitrogen has been noted in sapropel (in the range of 0.90 to 3.90%, average 2.10%). In mineral sediments (marl, lime, sand, clay) the nitrogen concentrations correlate with the organic material accumilation. Depending on lake sediment age and with due regard to the lithological type of sediments the nitrogen content in the organic material is as follows: 1.1-2.2% in Early Holocene sediments, 2.7-3.7 -- of Atlantic, 3.0-3.8 -- in Subboreal, 4.0-4.7 -- in Subatlantic sediments. This geochemical index made possible the subdivision of sediments accumulated during a period into stages. The indexes showing maximum nitrogen content of organic substance (lakes of Senno -- more than 3.55%, Rubovskoe -- 3.73 and Richi -- more than 2.24%) is typical for drainage lake and increasing autochthonous processes in the water and drier climatic environment. For the upper part of SA-sediments in the lake of Senno the maximum (10%) is due to anthropogenic eutrophication of the lake water. Unidirectional decrease of nitrogen in the organic material of AT-2 sediments in all the lakes studied shows the general specific changes of the natural environment, which was caused by the climate changes. The value of geochemical index with nitrogen agrees with the geochemical subdividion of sediments according to macro- and micrielement associations and their contents. It generally shows the possibility of using organic substance and nitrogen as geochemical indexes of the geochemical environment changes and for their correlation with the evolution of the bioclimate components in natural environment.
Matveyev A.V., Starodubova A.P., Kudelsky A.V., Aizberg R.Ye., Naidenkov I.V., Karabanov A.K., Kapora M.S.
Radon in natural and technogenic complexec of Belarus. pp. 151--161
Abstract: The problem of radon found in natural and technogenic complexes is discussed for the first time. Radiometric studies have been shown promising for revealing unstable geological object and some types of mineral occurrences (radon mineral water, oil deposits, etc.). Attention is drawn to medical and biological hazard of natural and technogenic radon emanations. A problem of a special state programme "Radon" development is raised. Possible sources of radon in geological space are analyzed. Acidic crystalline rocks (granite and granitoid) of the basement with localization of gaseous emanations in tectonic fault zones are identified as the principal sources of radon. It has been shown Rn background concentrations in soil air above fault zones do not usually exceed 0.5--1.0 KBg/m3, their maximum values ranging from 20.0 to 26.9 KBg/m3. Flow sources of Rn in fault zones are medical and biological hazards to human health the monitoring Rn content of air in residential area is no more than 200 Bg/m3, its real concentration may be much higher. When the Rn concentration in air of residential area is about 400 Bg/m3, the evacuation of people is proposed. Radon-bearing mineral water found within the Belarusian anteclise and showing Rn concentrations ranging between 665 and 870 Bg/l is characterized. A working scheme of the Belarus territory subdivision into regions showing ecological radon hazards of various degrees is proposed. Possible structure and principal executors of a special programme "Radon" suggested to be realized are discussed.
Kuznetsov V.A., Zhukhovitskaya A.L., Kurzo B.V., Vlasov B.P.
Geochemistry of lake sedimentogenesis in technocene environment influences. pp. 161--171
Abstract: Some geochemical features of lake sedimentogenesis going on under the impact of agrotechnogenesis -- agriculture and cattle-breeding, as well as radiotechnogenesis -- global (nuclear weapon tests) and accidental fallout (Chernobyl catastrophe) are characterized. Influence of agrotechnogenesis is apparent in the changes of chemical component associations, more intense sedimentation of clastogene and biochemogene products being more contrast in cattle-breeding case and is accompanied by considerable reconstruction of the biogeochemical system of lake basin. The agrotechnogenic impact in lake sediments goes down to 12--18 cm depth and coincides with the boundary between SA-2 and SA-3. The lower boundary of radioactive technogene contamination is determined from characteristics of lake basin, sediment composition, contamination levels on the drainage systems. It is at a depth of 10--15 cm in meromictic lakes and down to 50 cm -- in gomomictic ones. Radionuclide dynamics is also linked with the changes of their occurrence forms in the lake sediment strata. The mechnism of Sr-90 migration is connected with the redistribution of water soluble, acid soluble and firmlybounded compounds combinations. The limits of spreading, the directions of lateral and vertical migration of Chernobyl radionuclides are ascertained. Maximum radionuclides concentrations are observed in the littoral zones of drainage lakes, in immediate proximity to source of terrigene materials.
Bordon S.V.
The formation of geochemical anomalies in the snow cover within urban territories. pp. 172--177
Abstract: The snow cover is one of the components of natural landscapes that influence upon their geochemical characteristics. The geochemical peculiarities of the snow cover are studied intensively within regions exposed to various geochemical stresses. The author presents factual evidences that illustrate geochemical anomalies revealed in the snow cover within urban territories. The snow melt water is of primary importance in studies of the chemical composition of an object under investigation. Concentrations of microcomponents in the snow cover depend on the technogenic load level. The geochemical series of trace elements arranged in order of decreasing the coefficient values is as follows: Y>Ni>Ga>Zr>Co=Nb>Cr>Ti>>Zn>Ba>Mn>Ge>Cu>Bi>Yb>Sn>Pb>Mo>V. The element classification into categories according to their variation coefficients does not depend on this element belonging to any geochemical group. There is also no any established relationship between the element category and its atomic weight.
Konishchev V.S.
Residual salt-troughs. pp. 179--181
CHRONICLE. pp. 182--196
COMMEMORATIVE DATES. pp. 197--201
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