Wyniki wyszukiwania - Biblioteka Nauki

1

Some remarks on distribution and genesis of palaeoincisions in the East Baltic area

100%

Bitinas A.

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tom Vol. 43, Nr 2

183-188

EN

Until the recent time genesis of palaeoincisions is one of the debatable problems among the Quaternary investigators in the East Baltic area. Distribution of palaeoincisions in the East Baltic area is closely correlated with the pre-Quaternary bedrock lithology and permeability as well as with recently active faults. These regularities confirm the theory that most palaeoincisions in this area were formed as subglacial tunnel valleys during catastrophic discharge of meltwaters, due to high pressure conditions beneath the ice sheet.

PL

W ostatnich latach geneza głębokich depresji w podłożu czwartorzędu stanowi jeden z najżywiej dyskutowanych problemów wśród badaczy czwartorzędu z państw wschodniobałtyckich . Rozmieszczenie tych głębokich obniżeń jest ściśle związane z litologią i przepuszczalnością skał podłoża, jak również z występowaniem czynnych uskoków w tym rejonie. Te zależności potwierdzają przypuszczenie, że powstanie większości depresji w podłożu czwartorzędu jest związane z rynnowym przepływem subglacjalnym podczas katastrofalnego odpływu wód roztopowych w warunkach wysokiego ciśnienia panującego pod lądolodem.

2

The Littorina Sea at the Lithuanian Maritime Region

63%

Bitinas A. , Damušyte A.

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tom Vol. 11

37-45

EN

In the recent decade a number of data of different investigations (pollen, diatom, molluscs analysis, lithological investigations, dating by methods of absolute geochronology, etc.) have been collected during the large-scale geological mapping of Lithuanian Maritime region (Lithuanian Coast). The results of investigations confirmed that there were three Littorina Sea transgressions at the Lithuanian Coast: the first manifested approximately in 8500-7800 conventional 14C years BP, the second (maximal) - in 6200-5900 and the third - in 5300-4000 conv. 14C years BP. The Post-Littorina Sea maximum was in about 3600-3400 conv. 14C years BP. The Littorina Sea shoreline displacement curves were carried out. The present-day positions of shorelines of the Littorina Sea as well as other Baltic basins are displaced in different altitudes in separate parts of the Lithuanian Coast due to oscillatory neotectonic movements of Earth crust blocks during Late Glacial and Holocene.

3

Glaciotectonic features in Lithuania

63%

Aleksa P. , Bitinas A.

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tom Vol. 44, Nr 1

9-13

EN

Systematic investigations of glaciotectonic features in Lithuania started in 1994. The first glaciotectonic review map of Lithuania has been carried out as a constituent part of the glaciotectonic map of central Europe. Two groups of landforms linked with glaciotectonic structures (composite ridges and massifs, drumlins and flutings) have been distinguished. Distribution of the pre-Quaternary megablocks in the Quaternary deposits is presented also, and the number of megablocks composed of rocks of different age and lithology is directly proportional to their extension in the sub-Quaternary surface. The other more detailed investigations of glaciotectonic features in Lithuania are connected with regular geological mapping in scale of 1:50 000. Results of the first detailed studies of glaciotectonic features (folds, thrust faults, diapirs) investigated in two outcrops in southeastern Lithuania and in the Lithuanian maritime region are presented in the paper.

4

Coastal dune dynamics along the northern Curonian Spit, Lithuania : toward an integrated database

38%

Bitinas A. , Dobrotin N. , Buynevich I. V. , Molodkov A. , Damušytė A. , Pupienis D.

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tom Vol. 62, No. 3

553--562

EN

Sand dunes are the most prominent subjects of geological and geomorphological interest along the Curonian Spit - a mega-barrier that separates the Curonian Lagoon from the Baltic Sea. To date, an assessment of various parameters of migrating dunes along the spit has been based on comparative analysis of old maps or aerial and satellite images, as well as geodetic measurements. These investigations have allowed assessment of dune dynamics over a relatively short historical period (~1700s to present). The most recent detailed investigations of the Dead (Grey) Dunes along the Lithuanian part of the spit using ground-penetrating radar (GPR) and magnetic susceptibility (MS) surveys, supported by a radiocarbon (14C) chronological framework of palaeosols and infrared optically stimulated luminescence (IR-OSL) ages of sand horizons, have advanced our understanding of aeolian landscape evolution. The interpretation of dune activity and stability phases has been generally based on IR-OSL dating results of the sand layers located between radiocarbon-dated palaeosols. However, the influence of soil-forming processes on the IR-OSL dating results related to possible migration of natural radioactive isotopes via aeolian sand layers has not been previously considered. Hypotheses of dune reactivation and migration caused by abrupt regional climate shifts, catastrophic forest fires, anthropogenic influence, and more local forcings have been tested. An integrated approach to dune investigations has offered an estimate of the rates of sand accumulation and key phases of aeolian dynamics during both stormy and calm periods, as well as helped to extend the record of dune evolution to the mid-Holocene. The palaeoenvironmental and palaeodynamic reconstructions of the Dead Dunes suggest that this mid-Holocene phase of dune activity was of a local character and likely did not exceed several centuries.