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

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

Geological Quarterly

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2018

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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.

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Anomalous fading of IR-stimulated luminescence from feldspar minerals : some results of the study

Molodkov A., Jaek I., Vasilchenko V.

Geochronometria

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2007

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Vol. 26

11-17

EN

An increasing amount of evidence shows that the use of feldspars in luminescence dating may suffer from significant age underestimates, which are thought to result from anomalous fading. In the hope of finding a solution to the problem we undertook physical investigations of kinetics and temperature dependencies of tunnel afterglow of these minerals. As a result, the method of the direct detection of the tunnel transitions from the dosimetric traps is proposed. Some other relevant results obtained are also presented and discussed. Particularly, the probable reasons of absence of effects of anomalous fading in the feldspar samples investigated in the present work are elucidated.

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Middle pleistocene stratigraphy in the light of data from the vilkiskes site, eastern Lithuania

Satkunas J., Molodkov A.

Polish Geological Institute Special Papers

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2005

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Vol. 16

94--102

EN

The Vilkiskes outcrop is approximately 40 metres high section of Quaternary sandy sediments, exposed in the slope of the Neris River valley and is located 15 km upstream from the city of Vilnius. The section is composed mainly of sand with one till layer in the middle part. The outcrop is of particular interest due to typical section of sandy formation presumably of lacustrine origin, occurring under the till. This formation is widely distributed in the vast area in between Vilnius city and Nemencine town, according to the data of geological mapping, and represents a particular period of nonglacial sedimentation of Saalian time. The new optically stimulated luminescence (OSL) dates (determined by A. Molodkov), obtained from the Vilkiskes section, fall into the time span of 307-230 and 147-137 ka. The age of the lower part of Vilkiskes lacustrine section (dated 307-230 ka by OSL) looks closest to the two ice free stages, which can be correlated with oxygen isotope stages (OIS) 7 (236-186 ka) and OIS 9 (328-301 ka). Ages of about 147.1 and 136.7 ka are obtained near the immediate contact with the underlying glacial lithocomplex. Assuming OSL ages, conditions of occurrence and palaeopalynological characteristics, the interval of the Vilkiskes outcrop with OSL dates falling into the time span 236-186 ka (OIS 7) can be introduced as the last Middle Pleistocene (Drenthe-Warthe) ice free interval in Lithuania, most probably, separating the Zemaitija and Medininkai stadials. The interval dated 147.1 and 136.7 ka is interpreted as the Pamarys Interstadial that tentatively can be correlated with the Zeifen Interstadial in the Kattegat Depression suggesting the existence of a ?Younger Dryas?-type climate oscillation just prior to the OIS 6/5e boundary.

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The last Middle Pleistocene interglacial in Lithuania : insights from ESR-dating of deposits at Valakampiai, and from stratigraphic and palaeoenvironmental data

Molodkov A., Bolikhovskaya N., Gaigalas A.

Geological Quarterly

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2002

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Vol. 46, No 4

363-375

EN

The penultimate (Snaigupele, oxygen isotope stage (OIS) 7) interglacial has proved controversial in Lithuania because of palynological similarities between Holsteinian, SnaigupĹlĹ and Eemian interglacial deposits in the Lithuanian terrestrial record. Furthermore, no warm interglacial period has been recognised between the Holsteinian (OIS 11) and Eemian (OIS 5) in the neighbouring Baltic countries, Estonia and Latvia. In this study, we provide electron spin resonance (ESR) dates of two freshwater mollusc shell samples collected from lacustrine sediments at the Valakampiai site which are thought to be Snaigupele in age. Shells analysed gave mutually consistent dates of 116.0 š 10.8 and 110.0 š 12.1 ka with an average age of about 113.3 ka. These dates are thus significantly younger than OIS 7, and more closely correspond to OIS 5 (Eemian). The possible occurrence of this late Middle Pleistocene OIS 7 interglacial episode in Lithuania and other Baltic countries is evaluated with reference to the nearest and most complete long terrestrial sequences from the central and southeastern parts of the East-European Plain.

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ESR ages of three lithuanian mid-late pleistocene interglacials methodical and stratigraphical approach

Gaigalas A., Molodkov A.

Geochronometria

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2002

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Vol. 21

57-64

EN

The electron spin resonance (ESR) dating was used for freshwater mollusc fossils taken from interglacial deposits at the Gailiunai and Neravai sites (Butenai/Holsteinian In-terglacial), Valakampiai site (Snaigupele/Drente-Warthe Interglacial), Jonionys and Netiesos sites (Merkine/Eemian Interglacial) in Lithuania. Freshwater mollusc samples from the Butenai/Holsteinian and Merkine/Eemian Interglacials estimated by ESR yielded different ages: Butenai O 455.0 to 307.0 ka and Merkine O 112.5 to 101.5 ka BP. Two ESR dates determined for Snaigupëlë Interglacial deposits suggest an average age of about 113.0 ka. This is therefore younger than expected from the palynological data, and it places Snaigupëlë into the interglacial stage, possibly assigned to the MIS 5d that can likely be correlated with the Merkine/Eemian Interglacial (s.l.). Thus, further studies of the deposits and additional ESR dates are needed to make sure that the Snaigupele bed is really much younger than expected (about 200 ka) in all recognized sites in different parts of Lithuania.