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Peculiarities of sedimentation conditions in the oxbow lakes of Dubysa River (Lithuania)

Gaigalas A., Pazdur A., Michczynski D., Pawlyta J., Kleišmantas A., Melešyte M., Rudnickaite E., Kazakauskas V., Vainorius J.

Geochronometria

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2013

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Vol. 40, no. 1

22-32

EN

Abundant wood remains and buried trees have been found in the western part of Lithuania near Zakeliškiai and Lyduv?nai on Dubysa River (a tributary of Nemunas River) where deposits are rich in organic remnants and buried soils. In Zakeliškiai and Skiručiai sections of Dubysa River ox-bow sediments were investigated by various methods (dendrochronological, carbonate, granulometric, pollen and mollusc fauna analysis). In addition, these sections were dated using the radiocarbon method. Samples were collected from deposits of Dubysa River outcrops. The studied oxbow lakes have existed for more than 5 thousand years (from ca. 4300 BC to 1000 AD). During this period or-ganic rich deposits with trees and branches were formed in the oxbow lake. This indicates that at the end of Atlantic, during Subboreal and in the early Subatlantic periods there was a forest growing that contained mainly oaks which were falling down into an oxbow lake and later were covered by sandy and silty deposits. The granulometry of alluvial deposits, as well as the mixture of medium-grained sand and silt show different stages of Dubysa River palaeochannel formation: riverbed and oxbow lakes. Three climate warming cycles were revealed according to carbonate analysis data in all investi-gated sections. The rheophile thermophilous Holocene age molluscs species Bithynia tentaculata L., Unio cf. crassus Philipsson, Pisidium amnicum (Müller), Theodoxus fluviatilis (Linnaeus) have been found. The pollen composition and sequences have been divided into five local pollen assemblage zones (LPAZ) and described according to pollen spectra in each zone. In this way it is possible restore palaeoclimatic coherent evolution, trends and cyclical change.

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Geochronological and sedimentological interpretation of interglacial aquatic sediments based on TL dating

Fedorowicz S., Gaigalas A.

Geochronometria

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2010

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Vol. 35

75-83

EN

For the first time sedimentological interpretation of absolute ages obtained by thermoluminescence method on aquatic interglacial sediments was made. The analyzed size fractions of quartz grains were 160-250, 125-160, 100-125, 80-100 and 63-80 µm. The youngest and most reliable ages from 22 analyzed samples were obtained from the following quartz grain size granulometric fractions: 160-250 µm – 3 cases, 125-160 µm – 7, 100-125 µm – 6, 80-100 µm – 3 and 63-80 µm – 2 cases. Therefore, it may be concluded that the most suitable fractions for thermoluminescence dating are 125-160 µm and 100-125 µm. While evaluating the results of thermoluminescence dating it is necessary to take into account the procedure of sampling from layers of interest, their lithological composition, first of all granulometric, sedimentary environment, including sources of material, the material getting to the load flows, transportation mode and basin differentiation. From all the granulometric fractions of a sample, age of fine-grained fraction (63-80 ěm) may be explained by the input of aeolian dust to a basin and sedimentation along with clasts brought to a lake by water flows. Aeolian sand storms performed precise multigenetic sedimentation that was active during that time. Bimodality of granulometric composition is defined by input of material from various sources of different composition. Older ages were obtained in the case of positive granulometric asymmetry. After sedimentological interpretation of thermoluminescence (TL) dating we can state that formation of aquatic fine-grained sands occurred 83.6š10 – 116.1 ±13 and 130.2 ± 15 – 276.4 ± 32 thousand years (ky) ago. Those geochronological zones coincide with interg lacial periods of Merkine (75.5-114 ky) and Snaigupele (180-280 ky) in Lithuania.

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Stable isotopes (H, C, S) and the origin of Baltic amber

Gaigalas A., Halas S.

Geochronometria

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2009

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Vol. 33

33-36

EN

New results of isotope analysis of light elements (H, C and S) of a dozen Baltic amber samples are described and discussed. Carbon isotope composition was nearly constant (ca. -23‰), whereas sulphur and hydrogen varied in their isotope compositions from +4 to -28‰ and from -171 to -213‰, respectively. The formation and subsequent evolution of this material since its origin in Paleogene time until present is outlined.

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Chronology of buried soils, forest fires and extreme migration of dunes on the Kuršių nerija spit (Lithuanian coast)

Gaigalas A., Pazdur A.

Landform Analysis

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2008

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Vol. 9

187--191

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The trace fossil Asthenopodichnium lithuanicum isp. nov. from Late Neogene brown-coal deposits, Lithuania

Uchman A., Gaigalas A., Melešyte M., Kazakauskas V.

Geological Quarterly

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2007

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Vol. 51, No 3

329-336

EN

A new fresh water ichnospecies of Asthenopodichnium Thenius, A. lithuanicum, is distinguished by its pouch-like shape with a J-shaped limb that is distinctly wider than the remaining part of the pouch. It was produced in a stiffground at the top of a mineral-rich brown-coal layer of Neogene age by a suspension feeder forming pouch-like domichnial cavities. Mayfly larvae may perhaps be considered as candidates for its tracemaker. Other arthropods (amphipods, isopods) are also possibilities. The brown-coal layer was exposed during the Neogene by river erosion, was colonized by the tracemaker (locally two colonization events took place) and in the Pliocene covered by distal crevasse and river channel sands.

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Entropy of Pleistocene till composition as an indicator of sedimentation conditions in Southern Lithuania

Baltrūnas V., Gaigalas A.

Geological Quarterly

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2004

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Vol. 48, No 2

115--122

EN

The two most complete and stratigraphically most reliably identified Pleistocene sections in Southern Lithuania were chosen as the object of this study. Variations in relative entropy were assessed from the average data on the grain size,mineral and petrographic composition of the individual stratigraphically identified till beds. Data obtained in the current study showed that the relative entropy of till composition, which characterises the even distribution of the components according to relative parameters (such as the fraction intervals and, the number of minerals), indicates that the till composition was modified by matter dispersion (mixing) and condensation (concentration). The relative entropy of the content of different till components (grain size fractions, heavy and light minerals, petrographic groups) in glacial units of various ages is different and indicates different parameters of glacial dynamics and different routes of glacier movement. Also, the relative entropy of till composition in the direction of glacier movement shows repetitive patterns, which are predetermined by loading of the bottom layers of the glacier with till material up to its maximum concentration, followed by their settling. Ice loading with till material proceeds by grinding and mixing the transit and indigenous exarational material until the till mixture reaches its maximum density (volumetric weight) and becomes close to the optimum mixture.

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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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Palaeomagnetism of Lithuanian Upper Pleistocene sediments

Gaigalas A., Abrahamsen N., Kazakauskas V., Melešyte M.

Geochronometria

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2002

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Vol. 21

65-72

EN

In the Lithuania, a palaeomagnetic study of Upper Pleistocene and Late Glacial sediments at five sections has been carried out. The palaeomagnetic study of the varved clays in the Maskauka, Didžiasalis and Girininkai sections cover the time interval since 18,000 to 14,000 BP and Mančiagire section covers the time interval since 12,700 to 11,630 BP. The palaeomagnetic research of the Merkine (= Eemian) Interglacial sediments (Netiesos section) cover the time interval since 112.0š25 to 101.5š11.5 ka BP. The declination (D), inclination (I) and intensity (J) of the natural remanent magnetization of glaciolacustrine clays (Maskauka, Didžiasalis and Girininkai sections), as well as Merkine (=Eemian) Interglacial deposits (Netiesos section) and interstadial sediments (Mančiagire section) were measured. The result of these studies is presented in diagrams. The study reveals that considerable palaeomagnetic information can be obtained from the varved clays.

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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.

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Stable isotopes as record of climatic changes of Daniglacial in Lithuania

Gaigalas A., Pazdur A., Hałas S., Pawlyta J., Kazakauskas V.

Geochronometria

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2001

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Vol. 20

81-86

EN

Development of glaciolacustrine basins and varved clay sedimentation in Lithuania are closely connected with the course of ice retreat during Daniglacial time from 16,000 till 13,000 BP. Isotopic composition (delta 13C and delta 18O) of chemogenic carbonaceous samples from glaciolacustrine varved clays, which spread near glacier edge of South-Lithuanian (Balbieriýkis section), Middle-Lithuanian (Girininkai section) and North-Lithuanian (Joniškelis section) Phases of the Baltija (Pomeranian) Stage of Nemunas (Vistulian) Glaciation, has been studied. The obtained stable isotope data well confirm climatic changes of Daniglacial time in Lithuania. The gradual warming of climate is connected with the South-Lithuanian to Middle-Lithuanian and the Middle-Lithuanian to North-Lithuanian Interphasials as well as with the South Lithuanian interoscillations. The Interphasial lacustrine sedimentation with rhythmical lamination of carbonaceous sediments was observed in the middle part of the Balbieriýkis section (at a depth of 3.1-5.9 m). The following climatic changes of Daniglacial time in Lithuania are distinguished: (1) stadial (3000-6000), (2) glaciophasial (500-1000), (3) glaciooscillation (500-1000) years and (1) interstadial (1000-2000), (2) interphasial (250-450), (3) glacio-interoscillation (20-40) years. Regular succession of Daniglacial climatic and sedimentation changes in the local periglacial glaciolacustrine lakes, conditioned by recession of the last Scandinavian ice sheet, was revealed in the glaciolacustrine-lacustrine sediments for the first time.

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Radiocarbon age of late pleistocene glacigenic sediments in jonionys section of Merkine (Eemian) interglacial

Gaigalas A., Pazdur A., Pawlyta J.

Geochronometria

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2001

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Vol. 20

75-80

EN

The stratotype of Merkine (Eemian) interglacial in Lithuania is the Jonionys section near Merkine town in south Lithuania. The lacustrine sediments containing rich fossil flora in this section were formed under the conditions of Merkine interglacial and Nemunas (Vistulian) glacial. The fossil-bearing Merkine deposits are overlain by a probably complete sequence of Early Nemunas and partly of Middle Nemunas deposits. Rewashed till-covered organic sediments were found in the upper part of Jonionys section. The exact age of glacial sediments of this section has remained largely unknown. Peat with wood remnants under the rewashed till have been investigated in Gliwice Radiocarbon Laboratory (Gd-10825: 31,500+2300/-1800 BP and Gd-14000: >31,000 BP). Its deposition probably took place just before the maximum of the last glaciation. In Jonionys section the Merkine interglacial, Early and Middle Nemunas nonglacial sediments were probably accumulated in the time of climatic fluctuations, but without glacigenic sedimentation. The glacigenic sediments in the upper part of Jonionys stratotype section are younger than 30,000 BP and belong to the Late Nemunas glacial maximum. Recent radiocarbon dating are important for the establishment of the standard area of the European Würm (Vistulian, Valdaian, Poozerian and Nemunas) glacial.

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Correlation of 14C and OSL dating of late pleistocene deposits in Lithuania

Gaigalas A.

Geochronometria

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2000

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Vol. 19

7-12

EN

Otically stimulated luminescence (OSL) studies on the 14C dated section of the Middle Nemunas (Middle Vistulian) limno-alluvial deposits of the Jiesia river were made. The most deposits from palaeolake with broad, low-gradient floors of Middle Nemunas interstadial in Central Lithuania are inferred to be more favourable to accurate OSL dating. OSL procedures and sedimentation processes critically affected the accuracy of OSL ages.