Èçäàòåëè: Èíñòèòóò ãåîëîãè÷åñêèõ íàóê Íàöèîíàëüíîé àêàäåìèè íàóê Áåëàðóñè è Áåëîðóññêîå ãåîëîãè÷åñêîå îáùåñòâî, Ìèíñê, Ðåñïóáëèêà Áåëàðóñü
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ËÈÒÎÑÔÅÐÀ Èçäàòåëè: Èíñòèòóò ãåîëîãè÷åñêèõ íàóê Íàöèîíàëüíîé àêàäåìèè íàóê Áåëàðóñè è Áåëîðóññêîå ãåîëîãè÷åñêîå îáùåñòâî, Ìèíñê, Ðåñïóáëèêà Áåëàðóñü |
Abstract: The rock evolution in the course of the East European platform cover development within Belarus is described by several vertical formation series corresponding to specific structural complexes. Some particular formations have been differentiated by the predominance of formation-composing rocks in them, that create stable parageneses. 29 terrigenous (àluminosilicate), 9 carbonate, 3 sulfate-chloride (halogenic) and 8 magmatic formations have been distinguished in the platform cover of the region. Minerogenic peculiarities and indicators of various type formations that are representative of paleodynamic environments and events, as well as conditions in which minerals were deposited have been ascertained. The paper deals with terrigenous and carbonate formations. Terrigenous rock associations have been revealed in all structural complexes of the platform cover of the region. Formations of monomictic composition were mostly abundant in the Riphean, those of oligomictic and polymictic composition are widespread in deposits of the Lower Vendian, Permian, Triassic and Paleogene. Formations developed at the early platform stages under oxidation conditions of humid and glacial lithogenesis are typically red coloured. Petroliferous, carboniferous, schist, phosphate-and glauconite-bearing rock associations have been differentiated in the composition of terrigenuos deposits. Carbonate rock associations are abundant in the stratigraphic range from Vendian to Upper Cretaceous deposits. Fully developed carbonate formations had accumulated in the Phanerozoic only. These differ essentially in the composition and genesis. Their alternation in time and an increased contribution of biogenic carbonates are associated with the general evolution of the biosphere and depositional environments. Almost all oil deposits in the Pripyat Trough are confined to carbonate formations.
Abstract: The Dianulites Genus (order Trepostomida, suborder Esthonioporina, family Dianulitidae) is widespread in the Lower and Middle Ordovician (Arenig, Llanvirn, Caradoc (lower part)) of the East European Platform (EEP). This genus is actually a "Baltic" genus. Dianulites was chosen as a key genus of bryozoan communities of the East European Platform (Pushkin, 1986; 1987). The species composition of Dianulites (only Arenigian-Llanvirnian species) was revealed from numerous data available, a range of the stratigraphic distribution of separate species was determined more accurately, a diagram of the genus phylogenetic development during the EEP Arenigian and Llanvirnian stages was composed. Two ways of the Dianulites evolution was revealed: the first (principal) one is represented by massive, in the main, hemispherical colonies; the second one -- by conoidal (rugose-like) colonies. The modem redescription of the Dianulites genus was given. 9 species of Dianulites were completely described: D. helenae (Modzalevskaya, 1953), D. multimesoporicus Modzalevskaya, 1953, D. collucatus sp. nov., D. eichwaldi sp. nov., D. modzalevskae sp. nov., D. lamanskyi sp. nov., D.fastigiatus Eichwald, 1829, D. petropolitanus (Pander, 1830), D. janischewskyi Modzalevskaya, 1953.
E.A. Krutous
Seed flora from Holocene deposits of archaeological sites in the Krivino bog massif (Belarussian Poozerie area). pp. 32--37
Abstract: The composition of the seed flora from two sections of Holocene deposits in the Krivino bog massif has been studied in order to reconstruct the paleogeographical conditions of the time of burial of archaeological artifacts. The Late-Neolithic and Bronze Age settlements of Osovets and Krivino were discovered earlier within the Krivino bog massif. The most interesting data have been obtained from the Osovets-2 section (at a depth of 0.0--1.1 m). 74 plant species have been identified and form 3 complexes. The first (lower) complex is an evidence of the beginning of deposition of peat strata within an overgrowing lake in the Atlantic period of the Holocene. Among water plants of that time different species of Potamogeton have been identified, and the amount of seeds of Najas marina, Caulinia flexilis, C. minor, Nymphaea alba and other species was found maximum for this section. The hydrological regime of the bog massif had changed several times during Subboreal and Subatlantic time. This is reflected in the seed flora composition (complexes 2 and 3), as well as in an increase in abundance of either bog, or water species remains. At the end of the Subatlantic period the Krivino massif started its evolution as a mesotrophic bog. It is confirmed by the presence of Scheuchzeria palustris seeds.
Ya.K. Yelovicheva, M.P. Onoshko
A marker horizon of Holocene sediments in the Sozh river valley. pp. 38--43
Abstract: The stratigraphic position of the "tree" alluvial horizon was defined, and some lithogeochemical indences of paleographical conditions under which it had been accumulated were used to substantiate its marker significance in Holocene sediments of the Belorussian Sozh river region, which is illustrated with the key section at the village of Veprin (Cherikov region). Palynological data suggest that oxbow-lake sediments represented by loam with tree relicts ("tree" alluvium) had been formed during the Middle Holocene (AT-1- S-2). At the villages of Berveni and Otor (Chechersk region) such alluvial sediments are associated with fluvial, creek, floodplain and boggy sediments and is combined with a bog ore horizon at this stratigraphic level, which gives a special marker significance to this part of Holocene strata. Some geochemical indices (contents, Corg distribution curve pattern, Fe2O3, Al2O3, SiO2:Al2O3, CaO, Mn, Ti, Zr, Cu and other trace elements, as well as natural radioisotopes K-40, Ra-226, Th-232) clearly reflect the paleogeochemical environmental changes due to climatic factors and correlated with corresponding stages and phases of the plant association evolution. The time correlations of this horizon with analogous formations in the Dnieper, Niemen river regions, as well as with those in the Vistula and other river valleys within the Poland territory are presented.
A.A. Makhnach, G.D. Streltsova, L.F. Gulis, V.I. Gulakova, V.V. Gulis
The texture type differentiation in Upper Devonian dolomite rocks from the Pripyat trough and Orsha depression. pp. 44--51
Abstract: The texture of dolomite rocks from the intersalt and subsalt carbonate complexes of the Pripyat Trough and Orsha Depression (the Gralevo quarry) was studied. The dolomite rock classification scheme by D. Sibley and J. Gregg was taken as a basis for the texture description. This classification allows a reproducible systematization of dolomite rocks according to their texture pecularities and may be genetically applied. According to the scheme the crystal size distribution and crystal boundary shape in dolomite aggregates are functions of the composition and temperature of dolomitizing fluids and depend on the dolomitized substrate structure. A texture formula was proposed to describe the dolomite rock texture type. The texture formula consists of the literal symbols defining the crystal size and shape and the numerical ones indicating a percentage of the given texture in a rock. Dolomite rocks were classified according to the crystal size distribution as unimodal and polymodal, according to the crystal boundary shape -- as planar and nonplanar, and rocks with pronounced and non-pronounced substrate structure were differentiated. The abundance of the dolomite aggregate texture was assessed considered using the statistical analysis. The distribution of dolomite rocks of the different texture type in Upper Devonian deposits of the Pripyat Trough and Orsha Depression was studied. The abundance of unimodal and polymodal units with pronounced and non-pronounced substrate structure was recognized. Fine- and medium-crystalline nonplanar dolomite rocks dominate in the Pripyat Trough and coarsely-crystalline planar dolomite rocks prevail in the Semiluky deposits exposed in the Gralevo quarry. The studied texture pecularities of the dolomite rocks show a polystage character of the dolomitization process occurring within the studied deposits, Diagenetic dolomitization probably took place at the initial stage in many sites and was due to Upper Devonian sea wate, at times and in some sites desalted, or vice versa salinized, and in some cases, possibly, due to brine and mixed fresh-brine media. The diagenetic symptoms were later on hidden by epigenetic dolomitization that occurred due to brines in the Pripyat Trough, and with the participation of dilute solutions like as mixed thalassic and meteoric waters in the Orsha Depression.
E.A. Vysotsky, N.S. Petrova, V.P. Dashkevich, V.S. Plutenko, I.A. Linnik
Geological structure and conditions of formation of the Oktyabrsky potash salt deposit in the Pripyat trough. pp. 52--64
Abstract: In 1993--1998 the new Oktyabrsky potash salt field situated in the north of the Pripyat through was prospected in Belarus 40 prospect holes were drilled in potash salt strata. A characteristic feature of this field is the presence of payable potash salt deposits developped in the upper part (Luban and Starobin beds) of the section of the Famennian salt-bearing formation. Ores of the minable horizons 0--8 and 0--9 are presented by red sylvinites, and those of the horizon 0--7 -- by carnallite rocks. In the field territory commercial pottassic deposits occur in the Oktyabrsky and Starobin syncline zones, as well as within a saddle dividing the Visha and Malyn brachyanticlines. Ores of the pottassic horizons 0--8 and 0--9 are of high quality, the KCl content is 40.51%, MgCl2 -- 0.11% and insoluble residue -- 4.74%. For the horizons 0--8 and 0--9 the total balance sylvinite ore reserves of the categories C1--C2 account for 637.16 million tons of raw salts (152.83 million ton of K2O), and balance reserves -- for 153.74 million tons (39.61 million tons of K2O). The selective excavation of sylvinite beds of the horizon 0--8 is considered preferable (average thickness of sylvinite beds 1 and 2 is 0.62--0.75 m and 0.75--0.87 m, respectively). In the section of the horizon 0--9 the selective excavation of the sylvinite bed 3 is possible (thickess averages 0.79--0.90 m). Rocks of the Devonian suprasalt clayey-marly formation are waterred in its section lower part at the contact with the salt-bearing formation. So, protective barrier pillars should be left during mining this field potassic ores.
A.A. Arkhipova, I.V. Naidenkov
Early Precambrian granitoids of Belarus: geodynamic position and metallogenic trends. Paper 2. Granitoids of the Smolevichi-Drogichin suture zone and Osnitsk-Mikashevichi volcanic-plutonic belt. pp. 65--73
Abstract: Within the Smolevichi-Drogichin suture zone (SDSZ) granitoids of various types had formed in the Early Proterozoic. The most ancient (2.0--1.8 Ga) among them are mesoabyssal calc-alkalic granitoids of the Vygonovo complex similar to the S-type and depleted of many trace elements. These appear to be the most recent magma differentiates originated from the same magma chamber as did granitoid rocks of the Mikashevichi complex (ca 2.0 Ga) situated eastwardly within the Osnitsk-Mikashevichi volcanic-plutonic belt (OMVPB). Granitoids of the Vygonovo complex could be formed within active continental margins or under collision setting. The other age group involves crustal calc-alkalic granitoids also widespread within SDSZ enriched in many rare lithophile and, sometimes, chalcophile elements, namely, mesoabyssal granitoids of the Bobovnia complex and hypabyssal granitoids of the Zhukhovichi complex dated at 1.96 Ga. Their formation could take place in hinterlands of active continental margins or under collision setting. Some regular changes are observed in the composition of granitoids and their potential ore content across the strike of SDSZ that are generally correlated with zones of active continental margins of Phanerozoic time. Mezoabyssal granitoids of calc-alkalic series poor in trace elements (Vygonovo complex) occur in the southeastern part; granitoids of the same geochemical type but enriched in many rare lithophile, rare-earth and chalcophile elements (Bobovnia complex) are found in the central part and northwardly along the zone strike; hypabyssal calc-alkalic granitoids with their pegmatoid type tending geochemically to plumasite leucogranites (Zhukhovichi complex) are located in the northwestern part of the zone.
R.Ye. Aizberg, R.G. Garetsky, N.P. Zapivalov
The problem of geological fluid dynamics in oil and gas basins. pp. 74--77
Abstract: A complex study of geological fluid dynamics within a basin (megasystem) and within a pool (macrosystem) reveals new peculiarities of the oil and gas generation, oil and gas migration conditions, formation and conservation of hydrocarbon deposits. The fractal analysis used to assess the fluid dynamics factors makes for ascertaining the general and individual features of various type destruction and convergence-collision oil and gas basins and, on this basis, the genetic relationships between their major elements: oil and gas generation centres, oil and gas accumulation zones, fields and pools.
V.S. Konischev
Oil-geological zones distinguished in supersalt Devonian deposits of the Pripyat trough. pp. 78--86
Abstract: Results of analyzing the oil-generation potential of supersalt Devonian deposits, conditions of the hidricarbon vertical migration from underlying deposits to supsalt rocks, oil traps, reservoirs, cap rocks and paleogeodynamic environments where oil pools had been accumulated and stored were used to compile a map of oil-geological zones of supsalt Devonian deposits in the Pripyat Trough. The Pre-Rechitsa, Pre-Malodusha, Pre-Skolodin and Pre-Narovlia zones where the hydrocarbon generation is possible have been distinguished. These coincide with the axial parts of the same-name synclinal zones recognized from the surface of Famennian salt strata. Within these zones supsalt Devonian deposits occur deeper than 3.000 m, where they enter the main oil generation phase. The South-Rechitsa, North-Malodusha, South-Prudok, South-Kamenka, North-Narovlia zones have been distinguished on the slopes of neighbouring salt swells as zones of supposed oil generation. Oil and gas pools could be formed in traps within these zones as a result of hydrocarbon lateral migration from axial parts of synclinal zones, or vertical migration from uppersalt, intersalt and subsalt deposits through the active salt of the halite substrata found on the steep flanks of salt stocks. Numerous boreholes were drilled within the most promising South-Rechitsa and South-Malodusha zones of supposed oil accumulation, but no oil-bearing horizons were revealed from their logs. Paleogpodynamic conditions were unfavourable for oil pool storage. Therefore, supersalt Devonian deposits should be considered as showing very little promise for oil, and hydrocarbon pool prospection is recommended there within zones of supposed oil and gas accumulation only simultaneously with prospecting deposits in underlying deposits.
M.I. Israpilov
The lithospheric plate drift inversion in the Holocene. pp. 87--97
Abstract: The International Longitudinal Project, carried out during 70 years, indicated undoubtedly that nowadays the directions of drifts of lithosphere plates in the Northern Hemisphere are opposite to those, predicted by the Theory of Plate Tectonics (TPT). Results of these measurements have no satisfactory explanations and some doubt exists about this conception. It is shown in the article that the observed drift of the lithosphere plates is explained by the inversion, happened during the second half of Holocene and continued by an inertia at present, doesn't contradict the TPT conception, but requires some refinements.
Abstract: Repetitive observations of the geomagnetic field elements have been carried out at the stations of Pleschenitsi and Gostbische. The estimated anomalies of the secular course of a module of the full vector of the geomagnetic field are 3.9 nT at Pleschenitsi, and 10.4 nT at Gostbische. The declination and inclination values at these stations did not almost change within 1996--1997. The secular course of the geomagnetic field was recorded at the station of Pleschenitsi within 1960--1999. A module of the full vector of the geomagnetic field tends to increase with a rate of 22 nT/yr. Against the regional increase a periodic component observed within 1972--1999 shows almost sinusoidal oscillation with a period of ca 26--30 years with an amplitude of 55--60 nT. The first minimum of this local component maybe referred to 1967--1968, the second minimum -- to 1993--1995 and the maximum between them -- to l979--1980. So, the local oscillations of the secular course of the geomagnetic field is well correlated with the maxima and minima of the solar activity. The linear tendency of the geomagnetic field increase determined at the Pleschenitsi station can be interpreted as associated with deep-seated sources forming the main magnetic field of the Earth, As to a periodic component imposed to this linear tendency, its nature is most likely due to external perturbations of the geomagnetic field, solar and magnetic activity. The Pleschenitsi and Gostbische stations are situated in a zone of junction of the largest segments of the East-European Craton -- Fennoscandia and Sarmatia. This zone is described by elongated long palaeo- and recent intensive depth tectonophysical processes that are evidenced by data of the above repetitive gravimetric observations. It allows us to interpret the obtained anomalies of the secular geomagnetic field at the Pleschenitsy and Gostbische stations as an information about recent tectonophysical processes. The data obtained as a result of study of the secular course of the geomagnetic field within the territory of Belams suggest, firstly, that a system of observations within the testing ground and a system of stations of the secular course observation complement each other and, secondly, that the recent tectonophysical processes occurring in the tectonosphere of Belarus create the geomagnetic field variations well measurable over a period of one or two years.
A.P. Yemelianov †, V.M. Kolkovsky, R.R. Seroglasov
The parameters of the seismic regime in the Soligorsk industrial region. pp. 107--114
Abstract: The instrumental seismological observations started in the Soligorsk region in the eighties. About 1.000 seismic events of various classes were recorded. Most of earthquakes are confined to the specific zones of active faults. The Northern, Central, Southern zones and the Chervonaya Sloboda--Malodusha fault are typified as such zones. The largest earthquakes happened in 1978 and 1983 occurred in these areas. The epicenters of three appreciable earthquakes are located within the investigation region. The epicenter of the earthquake happened on 10 May, 1978 is found near Soligorsk and associated with the Southern tectonic zone. The earthquake was estimated at 4-5 in MSK. The earthquake was manifested by rumbling, rattling of the window-panes, rocking of hanging things, creaking of furniture and floors on the first floors of wooden buildings. The total fallen rock weight was 3,000 tons. The earthquake was instrumentally recorded at the seismostations of Pleschenitsy and Obninsk. The earthquake of December 2, 1983 occurred approximately 40 km northeast of Soligorsk at an intersection of the Stochodsk--Mogilev and North-Pripyat superregional faults. It was accompanied by rumbling, rattling of window-panes, rocking of hanging things, creaking of floors and furniture. Some plaster cracks were noted. The earthquake was instrumentally recorded by seismostations at Naroch, Pleschenitsy, and Soligorsk. The earthquake magnitude was 9. The earthquake at the village of Pogost occurred on 15 March, 1998. Inhabitants told about window-panes rattling, spontaneous opening of the doors, movement of furniture, beds. People felt the floor rocking, many of them awoke. The earthquake magnitude was kV8+8.5. An intensity of ground shaking was estimated at VII in MSK. The paper cites the results of earthquake data processing withing 1997--1999 and the calculated parameters of the seismic regime: slope of repeatability curves, distribution of seismic activity and parameters of the largest earthquake. The repeatability curves showl a slope with a factor about 1. On the side of weak events the curves is nonlinear which may be probably explained by the fact that data are poorly representative. A correlation relationship was established between the maximum probable earthquake and seismic activity from the calculated seismic activity for earthquakes of the 5th class. It was determined that the magnitude of the maximum probable events is as high as 11. The probability of such event was estimated at approximately one per 10.000 years. The spatial isochron method was used for the focus depth estimation.
V.G. Levashkevich
Geothermy of local structures of the Pripyat trough. pp. 115--123
Abstract: The terrestrial thermal field pattern within salt dome structures, both in the vertical and lateral directions depends on the geometry of a structure, as well as on the ratio of thermal conductivity of rock salt and enclosing sediments. Therefore, it is necessary to apply corrections for the thermal conductivity contrast to determine undistorted heat flow values, or to consider data obtained for depths, where the influence of a salt massif is absent. A character of the thermal field variation within local structures was studied using mathematical modeling along selected profiles. The measured rock thermal conductivity values and the actual geometry of the main boundaries in the geologic sections were used. The variations of the heat flow vertical and horizontal components were shown both for the cross section, and over the region territory, which includes the Barsuki and Rechitsa oil fields, Vasilevichi depression, boreholes in the East Pervomaisk, Dnieper, Krasnoye Selo, and Vetkhin structures. The vertical components of the heat flow variations caused by the structural factor were shown within the platform cover in the depth range from 4 to 5 km. It results in the horizontal heat and mass transfer due to thermal diffusion. The horizontal heat flow intensity within some areas makes up to 20 -- 25 per cents of its vertical values. The localities of its "convergence" indicate the most probable sites of the hydrocarbon accumulation. Such areas could be found between the Vetkhin and Dnieper groups of drill holes. The heat sink occurs from the Barsuki structure and Vasilevichi depression in a direction to the Vetkhin area, therefore a narrow area around the Krasnoselskaya 213 and Vetkhinskaya 3 holes and further southeastwards should be considered promising for the hydrocarbon accumulation.
Abstract: The Sr-90 and Cs-137 desorption properties of floodplain silt, mud, meadow turf, humus sandy loam, peat, clay and limonite have been examined. It was shown that Cs-137 is most readily sorbed by clay which may be due to isomorphic substitutions in the crystalline lattice of the montmorillonite group minerals, and by peat where it forms slightly mobile combinations with humic acids and humin. Amorphous hydroxide compounds of ferrite type serve as good sorbents for Sr-90. Cs-137 migrate readily there in mud, where this isotope is desorbed by all experimentally tested reagents; river muds seem to contribute mostly to the redistribution of the isotope under the floodplain conditions. Sr-90 is sorbed equally by mud, humus sandy loam, clay and meadow turf. By the desorption effect the eluent cations may be arranged as follows: for radiocaesium -- Cs+ > Fe3+ > NH4+ > Ca2+ > H+, for radiostrontium -- Fe3+ > Sr2+ > H+ > Ca2+ > NH4+.
L.N. Ryabova, V.A. Kuznetsov
The organic matter of Holocene soils overlying loess loam: composition, transformation, indication properties. pp. 131--136
Abstract: It was shown that the organic matter (OM) may serve as an indicator of the soil formation time. The duration of the soil formation influences a quantity of humic acids (HA), their content rises with the total C increasing in soil; however, such a trend has not been determined in fulvoacid (FA). The fractional composition of the soil OM varies essentially under shallow burial, which is shown in increasing the C:N ratio, a quantity of free fractions and those combined with R2O3, in destruction of complexes (FA-3, HA-3, nonhydroluzed residue decrease in amount). The changes in the OM composition of soils are due to bioclimatic fluctuations in the Holocene period: the Atlantic period soils may be reliably determined from their humate composition with a domination of fractions linked with Ca; for Subboreal soils (the degradation of dark-colored soils) the fulvic-humate or humate-fulvic OM is typically formed in the upper part of the humus horizon, and that of humate composition -- in the lower part; during the Subatlantic period soils with OM showing zonal humate-falvic and fulvic-humate composition are formed, the fulvic content increases down the soil profile.
L.I. Vasilyeva, N.I. Tanovitskaya
Technogenic constituents of heavy metals in soils of Belarus. pp. 137--143
Abstract: The objects of investigation were small and medium towns of the Minsk region and big industrial center Minsk. The aim of the paper is to estimate a degree of the urban territory contamination by air pollution with the ecological geochemical parameters. The comparative investigations have been performed to study the Berezina biosphere natural reserve as the background area. Soils were sampled from the humus horizon of urban and natural alluvial landscapes. Samples were analyzed for the total heavy metal content, as well as for the forms in which they occur (Cu, Zn, Pb, Ni, Co, Cr). The forms of occurrence of heavy metals were determined following a three-stage scheme: 1 - mobile (eluent 1N CH3COONa), 2 -- relatively mobile or active (eluent 1N HCl), 3 -- firmly bound or inert form. A possibility to distinguish between the natural and technogenic constituents in assessing a degree of anthropogenic changes of the soil trace element composition with a coefficient of the soil technogenic transformation proposed by the authors has been established (active to inert form ratio),
S.N. Veremchuk
Geochemical description of the holocene buried soils in the Sozh river floodplain. pp. 148--151
S.A. Akudovich
The problem of the trace element origin in subsurface brines. pp. 152--153
ÎÁÇÎÐÛ. p. 154
ÕÐÎÍÈÊÀ. pp. 155--159
ÞÁÈËÅÈ. pp. 160--162
ÍÎÂÈÍÊÈ ÃÅÎËÎÃÈ×ÅÑÊÎÉ ËÈÒÅÐÀÒÓÐÛ. p. 163