Wyniki wyszukiwania - Biblioteka Nauki

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Geological, geomorphological and hydrogeological heritage in Lithuania

100%

Karmaza B. , Baltrunas V.

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tom Vol. 13

183-189

EN

Quaternary deposits are the most spread formations on the territory of Lithuania. They were formed during the Pleistocene glaciations and now they completely cover the territory of the country. Their thickness is up to 315 m. The standard Pleistocene and Holocene outcrops, large boulders, springs and expressive landforms are very typical here and form an essential part of the most picturesque landscapes of Lithuania. The official list of legally protected geological, hydrogeological and geomorphological geosites of Lithuania contains now 183 objects: 122 of them are geological, 32 hydrogeological and 29 geomorphological. The geological objects could be subdivided into 3 groups: erratic glacial boulders, outcrops and depressions. The outcrops are subdivided into 2 groups: Quaternary and Pre-Quaternary type outcrops. The hydrogeological objects (springs) are subdivided by genesis into 2 groups: ascending and descending springs. 29 geomorphological objects established in Lithuania are designed to reserve localities with typical or rare forms of relief bearing a great scientific and educational value. These objects are mostly mounts (5), dunes (5), eskers (5) and steep slopes (5).

PL

Utwory czwartorzędowe są najbardziej rozpowszechnionymi formacjami na obszarze Litwy. Powstały one podczas zlodowaceń pleistoceńskich. Obecnie pokrywają cały obszar kraju. Ich miąższość dochodzi do 315 m. Wzorcowe odsłonięcia osadów pleistoceńskich i holoceńskich, duże głazy, źródła i pełne ekspresji formy terenu są tu bardzo typowe i stanowią ważny element najpiękniejszych krajobrazów Litwy. Oficjalna lista prawnie chronionych geostanowisk geologicznych, hydrogeologicznych i geomorfologicznych obejmuje obecnie 183 obiekty: 122 geologiczne, 32 hydrogeologiczne i 29 geomorfologicznych. Obiekty geologiczne mogą być podzielone na 3 grupy: eratykowe głazy lodowcowe, odsłonięcia i obniżenia. W odsłonięciach można wydzielić 2 grupy: czwartorzędowe i przedczwartorzędowe. Obiekty hydrogeologiczne (źródła) można podzielić na dwie grupy genetyczne: źródła ascenzyjne i descenzyjne. Obiekty geomorfologiczne wyselekcjonowane na Litwie mają służyć ochronie obszarów z typowymi lub rzadkimi formami rzeźby, o wielkiej wartości naukowej i edukacyjnej. Są to głównie wzgórza (5), wydmy (5), kemy (5) i strome stoki (5).

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Geochronology and Palaeomagnetic Records of the Snaigupėlė Section in South Lithuania

70%

Baltrūnas V. , Maksimov F. E. , Kuznetsov F. Y. , Karmaza B. , Katinas V.

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tom Vol. 42, no.1

172--181

EN

The interglacial deposits in the South Lithuanian Snaigupėlė outcrop and borehole Snaigupėlė-705 are marked for different bedding conditions though the sections are in proximity of each other. In the borehole section, the interglacial deposits are thicker and bedding at a greater depth than the analogous deposits of the outcrop. In the Snaigupėlė outcrop, the highest compatibility of isochronic-correction dates, calculated using L/L (method of leaching) and TSD (method of total sample dissolution) models, was determined for combination of three samples. With the help of the f value (section of isochrones in the axis of ordinates), the contribution of the primary pollution with thorium was determined where, as based on corrected analytical data, isochronic-correction dating was performed: 18 14 127+ − ka years for the L/L model and 22 16 132+ − ka for the TSD model. Palaeomagnetic investigations showed that the section of lacustrine sediments in the lower part of Snaigupėlė outcrop were orientated by reversed magnetic excursion and in the upper part by normal magnetic polarity. Collation of the obtained data with the global geomagnetic scale showed that the palaeomagnetic inversion observed in the Snaigupėlė section was related with the Blake Event in the Eemian Interglacial.

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Characteristic of till formation during the Baltija (Pomeranian) Stage of the Nemunas (Weichselian) Glaciation in Lithuania

61%

Baltrunas V. , Karmaza B. , Dundulis K. , Gadeikis S. , Račkauskas V. , Šinkunas P.

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2005

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tom Vol. 49, No. 4

417--428

EN

Studies of the till structure and composition of the Baltija (Pomeranian) Stage of the Nemunas (Weichselian) Glaciation in Lithuania has enabled recognition of a multilayered till structure. This can be seen visually (colour, bed structure, interlayers, insertions of different composition and so on) and established from features determined by analytical and statistical methods (physical and mechanical properties, material composition, orientation and dip of longer axes of pebbles). Borehole log data from boreholes drilled during geological mapping showed heterogeneity within the subglacial till of the Baltija Stage and provided a preliminary picture of variations of its multilayered structure from S to N. This showed that two layers predominate in the subglacial till in the area of the South Lithuanian Phase while three layers are present in the area of the Middle Lithuanian Phase farther north. The petrographic composition of the gravel fraction as well as the orientation and dip of the long axes of pebbles measured in till beds in natural exposures and quarries further demonstrated the multilayered structure of the Baltija till. Research at key sections in areas of the subsurface extent of till of the East, South and Middle Lithuanian phases of the Baltija glacial recession confirmed the increase in the number of till layers from S to N. The physical and mechanical properties of the till also reflect its multilayered structure. Relative entropy values calculated for the grain-size frequency distribution of the Baltija till enabled evaluation of a change in its sorting along the direction of glacial ice advance from N to S. There is a correlation between the higher values of entropy of grain-size distribution and the rate of development of preferred orientation of longer axes of pebbles throughout the till section vertically. The formation of themultilayered structure of the Baltija till is ascribed to cyclic dynamics of the subglacial processes associated with the receding ice sheet; consequently, the number of subglacial till layers may be related to the marginal moraine ridges of different phases left by oscillation of the ice sheet margin during glacial recession.

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Sedimentary environment changes during the Early-Middle Pleistocene transition as recorded by the Daumantai sections in Lithuania

51%

Baltrūnas V. , Zinkutė R. , Katinas V. , Karmaza B. , Šeirienė V. , Kisielienė D. , Taraškevičius R. , Lagunavičienė L.

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2013

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tom Vol. 57, No. 1

45–-60

EN

Two sections (Daumantai-1 and Daumantai-3) in East Lithuania expose Early-Middle Pleistocene lacustrine-alluvial, deposits which lie on a thin Neogene layer and on older Devonian rocks. They are overlain by glacigenic deposits. Geochemical, palaeomagnetic, magnetic susceptibility, plant macrofossil, and diatom investigations were performed to determine the changes in the sedimentary environment. Cluster analysis of the geochemical variables (10 major elements, 16 trace elements, total organic and inorganic carbon) revealed the element groups and factors. The lowermost units are characterized by a major influence of local material and significant fluctuations in heavy mineral content. These fluctuations might reflect short-term climate changes. The transitional units have more expressed trends, especially as regards the trace elements and Zr/Ti. The uppermost units are characterized by a slight influence of local material and small fluctuations in trace elements. The data analysed enable the subdivision of the section into units related to changes in sedimentary environment. The boundary of the Bruhnes/Matuyama reversal in the Daumantai-1 and Daumantai-3 sections was detected by palaeomagnetic studies and enables the stratigraphical correlation of these deposits.