Sedimentary record and luminescence chronology of the Lateglacial and Holocene aeolian sediments in Lithuania

Sand dunes are common along the sea coasts of Lithuania and in some regions of the mainland part of the country. Until recently, the age of the aeolian deposits was only approximate because of the lack of radiocarsbon-dating of soils buried in dune deposits. A relatively new alternative method to direct dating of organic-free deposits is infra-red optically stimulated luminescence (IR-OSL). Using this method, we investigated the sedimentary history of some Lateglacial and Holocene depositional sites of Lithuanian dunes. The samples for IR-OSL dating have been taken from boreholes (Mančiagirè, Smalininkai, Žalioji Giria) and outcrops (Mančiagire and Ventes Ragas) in different dune massifs. The results indicate that the aeolian sedimentation in Lithuania started during the Younger Dryas. The termination of the aeolian processes in the continental part of Lithuania is correlated with the end of the Atlantic or the beginning of the Subboreal period; this can be explained by significant climatic changes during the Atlantic period. There were several periods of high aeolian activity during the Holocene, but these are asynchronous in different dune massifs and variations in the sedimentation rate occurred both vertically over the section and spatially across the massif.     

Identification of sources of chemical constituents in groundwater from the Vilnius wellfields, Lithuania

The only source of drinking water in Vilnius City, Lithuania's capital, is groundwater. It can be supplied from 20 wellfields situated in the City or its environs. About half of them (11) are located in the valley of the Neris River crossing the City. The exploited aquifers were formed by melting continental glaciers and modified by the river. Until 1990 groundwater resources had not been conserved—the per capita consumption for domestic use in Vilnius reached 350 l/day. After 1990, due to the increasing cost of supplying drinking water, its consumption was reduced by a factor of three. As pumping rates of wellfields in Vilnius were increased or decreased, the groundwater quality was changed significantly. It is mainly affected by the surface water and shallow aquifers of the hydrologic system. The unoxidised organic matter that enters the exploitable aquifers from rivers and polluted shallow groundwater consumes scarce oxygen resources, thus creating anoxic conditions favourable for increasing the accumulation of iron, manganese and ammonium. Modelling and monitoring data show that the concentrations of sulphates and chlorides in Vilnius wellfields indicate not only the rise of brackish water from below, but also downward seepage of polluted surface water into the aquifers.     

Isotope geochemistry and modelling of the multi-aquifer system in the eastern part of Lithuania

A steady-state groundwater flow model of three Quaternary intertill aquifers in the eastern part of Lithuania has been compiled. The distinction of separate modelled layers is based on hydraulic and isotope-hydrochemistry data criteria. ³H data were used to estimate the corrected groundwater age and were coupled with a groundwater-flow-dynamics model of the Quaternary aquifer system along a cross-section flow pathway from the Baltic Upland recharge area in eastern Lithuania towards the discharge area in the lowlands near the city of Kaunas in central Lithuania. The bicarbonate content in groundwater (214–462 mg/l) increases downgradient towards the lowland area. The other major constituents and total dissolved solids (TDS) have a trend analogous to the bicarbonate. The ¹⁴C activity of dissolved inorganic carbon (DIC) in the groundwater ranges from 41.4 to 85.7 pMC. With aquifer-system depth, active precipitation of aqueous solution takes place by dissolving minerals of calcite and dolomite and leakage of “old” groundwater from lower aquifers; the process is also traced by lower ¹⁴C and ³H activities and by more positive δ¹⁸O values in lowland areas.     

Spatial variability of topsoil contamination with trace elements in preschools in Vilnius,Lithuania

An investigation of the spatial variability of topsoil contamination level was performed in 49 preschool playgrounds located in Vilnius city and correlated with urban (height and age of the preschools and height of surrounding buildings) and natural (altitude) factors. Composite samples, consisting of 20–30 sub-samples, were collected from 10 cm topsoil layer with a 3–5 m distance from each other. Sieved fraction (< 0.63 mm) was ashed at 400 °C, ground to < 1.0 μm and analysed for the real total concentrations of 22 trace elements (Ag, B, Ba, Co, Cr, Cu, Ga, Li, Mn, Mo, Nb, Ni, Pb, Sc, Sn, Sr, Ti, V, Y, Yb, Zn and Zr) using optical atomic emission spectrophotometry. Information on construction year and height (number of building stories) of preschool and surrounding buildings was acquired from the Centre of Registers of Lithuania. Out of 22 analysed elements, 13 to a greater extent exceeded the background values in several areas and were used to calculate the total contamination index (Z_s13). Out of 49 analysed areas, 21 had moderately hazardous to hazardous levels of contamination as indicated by Z_s13. The main contaminating elements, exceeding the permissible concentrations were Ag, Cu, Mo, Pb, Sn and Zn, the origins of which coincide with city industry and traffic. Topsoil around the newer preschool buildings, despite their location, contained lower concentrations of contaminants, while areas at higher altitudes were more contaminated than those located at lower altitudes. The latter causality is biased, as the city industry, and hence the highest contamination, is in districts located higher above sea level than the remaining studied sites.     

Considerations regarding the definition of a geochemical baseline of elements in the surficial materials in areas differing in basic geology

The problem of a geochemical baseline in areas differing in basic geology was studied by comparing the results of regional geochemical mapping programmes undertaken in Finland and Lithuania using different sample media and a variety of analytical methods. The authors discuss issues relevant to the definition of a geochemical baseline.Most of the differences in geochemical baselines between Lithuania and Finland are due to the dissimilarities in basic geology, which in Lithuania is controlled by Palaeozoic and Mesozoic sedimentary rocks, but in Finland by Archaean and Proterozoic metamorphic and intrusive rocks. Other important factors are the geological processes that after the last glaciation created the present surficial materials. In Finland, for instance, the abundances of potentially harmful elements derived from crystalline bedrock tend to be higher than in Lithuania. However, in both countries element concentrations are higher in finely-grained marine and lacustrine sediments than in glacial till, and they are also higher in the finer grain size fractions than in the coarser fractions of till samples. Only a small proportion of the total heavy metal concentrations is bioavailable. Thus the baseline concentrations depend not only on the basic geology, but also on sample material collected, its grain size and the extraction method.     

Fifty years of IMOG (International Meetings on Organic Geochemistry)

IMOG2011 is the 25th of a series of international meetings on organic geochemistry that began in 1962. Thus, this 25th meeting marks the 50th anniversary year of IMOG, which has (a) had a rich history with meetings taking place in 11 different countries, (b) published Proceedings, titled “Advances in Organic Geochemistry,” from each meeting that now number 24 volumes totaling almost 18,000 pages, and (c) documented the content and development of the science of organic geochemistry. IMOG2011 adds a new milestone to the progress of organic geochemistry through time.     

Upper Pleistocene stratigraphy at the Medininkai site, eastern Lithuania: a continuous record of the Eemian-Weichselian sequence

Eemian—Weichselian sequences, located outside the maximum limit of the Late Weichselian ice sheet, provide excellent opportunities for the discovery of continuous sedimentary records encompassing the whole Last Interglacial/Glacial cycle. Such a sequence is recorded in a borehole (117P) through the succession in a small kettlehole lake located at Medininkai, eastern Lithuania. The succession consists of peat, gyttja and silt deposited on top of a Saalian till. Pollen and plant macrofossil analysis, lithological analysis, U/Th dating and mineral magnetic measurements on the sediments have allowed 19 lithostratigraphic units and 16 local pollen assemblage zones (LPAZ) to be identified. The palaeocarpological record reveals a clear transition from the Saalian Glacial to the Weichselian stadial and interstadial phases. The mineral magnetic parameters suggest a good correlation between the concentration of magnetic minerals and stadial and interstadial periods. The Merkine (Eemian) Interglacial and two Early Weichselian Interstadials, Jonionys 1 (Brörup) and Jonionys 2 (Odderade), separated by cryomers, are identified. Intervals interpreted as analogous to the Middle Weichselian Denekamp and Hengelo interstadials are also recognized on the basis of pollen assemblages. The results show alternating periglacial and interstadial palaeoenvironments in Lithuania during the Early and Middle Weichselian and are of importance for Late Pleistocene palaeoenvironmental reconstruction of the Baltic area as a whole.     

Timing of the last deglaciation in Lithuania

Boulders from the Grūda Moraine, which is associated with the maximum extent of the Scandinavian Ice Sheet (SIS) during the last glaciation, and the Baltija (also referred to as the South Lithuanian), the Middle and North Lithuanian moraines, which are associated with recessional stages of the SIS, were sampled for surface exposure dating using ¹⁰Be. By combining these data with existing radiocarbon ages, we developed a chronology for the retreat of the SIS margin in Lithuania. Our new ¹⁰Be ages suggest that the SIS margin began to retreat from its maximum extent at 18.3 ± 0.8 ¹⁰Be kyr. Based on a probable correlation of the Baltija Moraine with the Pomeranian Moraine in Poland, we infer that the Baltija Moraine was formed following a re-advance of the SIS margin. The ice margin retreated from the Baltija position at 14.0 ± 0.4 ¹⁰Be kyr. The SIS-margin retreat paused at least two more times to form the Middle Lithuanian Moraine at 13.5 ± 0.6 ¹⁰Be kyr and the North Lithuanian Moraine (tentatively correlated to the Pajūris Moraine) at 13.3 ± 0.7 ¹⁰Be kyr. Subsequent ice-margin retreat from the North Lithuanian Moraine represented the final deglaciation of Lithuania. Direct dating of these moraines better constrains the relation of ice-margin positions in Lithuania to those in adjacent countries as well as the SIS response to climate change.     

Evolution of the Miocene Tejeda magmatic system,Gran Canaria,Canary Islands

This paper is a companion to Clark (1988; hereafter Part I) which described the evolution of the Tejeda Magmatic System (TMS), a Miocene caldera complex, Gran Canaria, Spain, based on geochronologic, paleomagnetic and field data. In this study, petrochemical data are used to corroborate the history out-lined in Part I. Geochemical discriminant analysis shows that whereas the Extra-Caldera (EC) Mogan/Fataga volcanics are separated by a composition gap, no composition gap exists within the Intra-Caldera (IC) sequence. IC ignimbrites change rapidly but progressively from pantellerites and comendites to comenditic trachytes and finally to trachytes in a 0.47 Ma time interval. Significantly, the lower pantelleritic part of the IC series is similar to the EC pantellerites (units B, C and D) as expected based on results from Part I. The appearance of a compositional gap in the EC sequence is the result of flows having been trapped within the caldera during the 0.47 Ma Mogan-Fataga transition interval. The transitional IC sequence may be geochemically modelled by mixing of Mogan comendites and Fataga trachytes. The mixing was most probably induced by the high discharge of magma from the compositionally-zoned Tejeda magma body. The rate of change in erupted composition is best explained by imagining a continuous influx of Fataga or parental Fataga magma into a chamber whose previous silicic component (Mogan composition) was no longer being replenished and that the two magmas did not convectively mix prior to eruption. Repose times between successive eruptions in the lower to middle Mogan (from P1/T1 to A) were of order 30 000 a; the upper Mogan pantellerites and comendites/comenditic trachytes (B to F?) erupted once every 125 000 years or so. The longer repose time for the upper units is consistent with their more differentiated character.     

新的挑战 新的使命——附记国际地层委员会2002年6月全会

新世纪初国际地层委员会 (ICS)面临着来自两方面的挑战 :一是国际地质科学联合会 (IUGS)向 ICS提出硬性要求 :2 0 0 8年必须完成显生宙各个系、各个阶的全球层型剖面和点位 (GSSPs)的选定工作 ,有关分会不能再无限期地拖下去了 ;二是 ICS的自身思考 :将来是就此停步还是继续履行其职责、但改变其方向和托管方式 ?ICS必须面对现实 ,改革思变。动力地层学显示高分辨率的全球变化的地质过程是激动人心和具有强烈社会责任的一个挑战 ,因为当今全球环境的恶化是人类所面临的一个极其紧迫的重大问题。地层学在这项研究中将扮演重要角色。根据详细的化石记录 ,可以进行精确的地层对比 ,洞察控制全球变化的动态驱动力。将这个给地层学定向的地质过程作为一个新的任务是最有意义的。2 0 0 2年召开的 ICS会议主要目的是让各分会主席对 ICS未来的方向和组织结构取得一致意见 ;加强内部交流与合作 ,企划将来的活动 ;讨论如何应对来自 IU GS的挑战。文内简述各分会 (包括末元古系、寒武系、奥陶系、志留系、泥盆系、石炭系、二叠系、三叠系、侏罗系、白垩系、古近系、新近系、第四系等 13个地层分会 )在会上交流的情况 ,并对 ICS的未来发展方向、ICS的组织和机构性质、ICS的强项和弱势、GSSPs的综合地层学、建立新的?     

Pleistocene glacial deposits along the eastern periphery of the Scandinavian ice sheets - an overview

The Quaternary glacial sequences in the Baltic region in Estonia. Latvia and Lithuania are relatively complete and reasonably well studied. The maximum thickness of deposits (200 300 m) is found in the uplands and ancient valleys. Tills of several genetic types have been described and in this paper the present view on the structure of the Pleistocene cover is given. The ice movement and glacial sedimentation were controlled by climate. underlying topography and tectonic processes.     

Experience of the International Association of Geoanalysts as a Certifying Body

Reference materials (RMs) to support geoanalysis have a long history, dating back to the issuance of G-1 and W-1 in 1951. This paper addresses only one aspect of the most recent part of that history, the experience of the International Association of Geoanalysts (IAG) as a certifying body. In 2002, the Certification Committee of the IAG met in Potsdam to discuss becoming a certifying body able to produce RMs for the geoanalytical community. Following that meeting, the IAG developed and published a protocol to assure that IAG RMs would meet International Organization for Standardization (ISO) guidelines to the fullest extent possible. Many practical problems arise in the application of the recommendations of the ISO Guides to any one specific certification project. The recommendations describe the ideal; achievable reality is always somewhat less than that ideal, presenting a significant challenge to the IAG as a certifying body. This paper will summarise experience to date, while focusing on the most challenging issues, deriving uncertainties compliant with the Guide to Uncertainty in Measurement (GUM) and establishing traceability of certified values (CVs).     

Using soil and Quaternary geological information to assess the intrinsic groundwater vulnerability of shallow aquifers: an example from Lithuania

Lithuania, in the Baltic region of northern Europe, is heavily dependent on groundwater resources for its public water supply, with a large proportion, especially in rural areas, derived from shallow Quaternary aquifers. A national groundwater-vulnerability methodology, based upon the UK approach, has been developed on behalf of the Lithuanian Ministry of Environmental Protection as a possible basis for the future protection of shallow groundwater resources for the rural inhabitants. Some modifications to the UK methodology were required to enable archive data to be used. The four aquifer classes depicted on the final groundwater vulnerability map are based upon the assessed relative permeabilities of the uppermost Quaternary deposits. The derivation of the classification of soil-leaching potential required a reassessment of Soviet-based soil wetness and particle-size classes and a calculation of subsoil-saturated hydraulic conductivity. A preliminary validation of the final maps against available shallow groundwater samples suggests that the methodology satisfactorily predicts the intrinsic groundwater vulnerability. The final methodology, based upon its low-cost approach using archive data, is relevant to the current needs of Lithuania and can be applied in other regions of similar geology and climate. Electronic Publication     

Middle Valdaian forest environments at Biržai, northern Lithuania

Lacustrine sediments, 13 m thick, have been discovered under a Late Valdaian (Late Weichselian) moraine complex in a palaeokarst depression at Biržai, northern Lithuania. Wood fragments from silty layers in the basal part of the section were ¹⁴C dated at 34,440 ± 1500 (Vs-412) and 33,460 ± 1060 BP (LU-1633). Pollen analytical results suggest that taiga landscapes similar to the present-day environments in the Pechora Basin and eastern Urals occurred on the southern cryogenic grounds. Evidently, the ice sheet did not penetrate into the eastern Baltic region during the Middle Valdaian interval.     

Observed and calculated normal color indices and indices in three photometric systems

We estimate the reliability of previously derived normal energy distributions for stars by comparing normal color indices in three photometric systems (W BV R, uvby, and Vilnius) calculated using these distributions with indices derived from photometric observations. Earlier, we used photometric data from W BV R and uvby catalogs to derive normal color indices for these systems not available in the literature, in the form of mean color indices and indices obtained for representative groups of normal, unreddened stars. The results can be used to estimate both the quality of our normal distributions and the reliability of the normal color indices in the three photometric systems considered.     

Geological history of the Sibumasu Block in Peninsular Thailand: report of a Geologists’ Association Field Meeting in 2007

It is widely accepted that Thailand consists of two principal blocks or terranes, both of Gondwana origin, which collided and fused in the Late Triassic. The western of the two is the Sibumasu Block, and the purpose of this field meeting was to examine Peninsular Thailand where the succession reveals the nature of Sibumasu's Late Palaeozoic rifting from Gondwana in the context of the overall Phanerozoic history of this block. Sedimentary rocks ranging from Cambrian to Miocene crop out in Peninsular Thailand, as well as granite plutons which are aligned in N-S chains, the western chain of Cretaceous–Palaeogene age and those further east of Triassic age. Of particular importance in that history was the NNE-SSW Khlong Marui Fault belt which coincides with the conspicuous bend of the Peninsula; it formed the (present day) eastern boundary of a Late Palaeozoic rift and has been active intermittently since.     

Palaeogeography of South Lithuania during the last ice age

The palaeogeographical development of South Lithuania during the last ice age (Nemunas = Weichselian) was reconstructed by various methods. The recurring permafrost and cryogenic structures in the ground were an important phenomenon of the southeastern periglacial zone. The 3–4 lithocomplexes of the extraglacial cover correlate with the Lithuanian and Mid-European Late Pleistocene Weichselian (Nemunas) biostratigraphic divisions. In the northwest, the palaeogeography is influenced by the deglaciation during the Žiogeliai (Frankfurt) Phase and the Baltija (Pomeranian) Stage of the last ice age. The deglatiation process is shown in a series of palaeogeography maps. During the Weichselian, the SW–NE oriented middle part of the area, commonly regarded as part of the Vilnius-Warsaw-Berlin Urstromtal (ice-marginal streamway), underwent intensive interstadial fluvial erosion and accumulation, glacial erosion and sedimentation, followed by subsequent glaciofluvial accumulation on sandurs and glaciolacustrine sedimentation in a series of small basins.     

The 1984 symposium on clay-varve chronology in Stockholm

In 1984 the centenary of Gerard De Geer's invention of the clay-varve dating method was celebrated with a Nordic conference in Stockholm. This paper presents the history of the method as an introduction to the following pages summarizing some of the papers presented at that meeting.     

陇中黄土高原LAS在非均匀下垫面的观测优势及其在区域陆面模式验证中的初步应用

目前通用的通量观测技术涡动相关仪（EC）在区域陆面模式验证中存在能量不闭合和空间代表性有限的问题,寻求改进EC观测热通量的新技术是提高陆面模式验证效果的关键环节,大孔径闪烁仪（LAS）的出现有效改善了这一现状。基于黄土高原定西站2010年1月和6月的同步综合观测资料以及目前比较有代表性的陆面过程模式CLM的模拟数据,分析研究了LAS对EC观测地表能量不平衡问题的改进以及LAS对EC在区域陆面模式验证中的提高,结果表明：LAS可有效解决EC观测存在的地表能量不平衡问题,提高EC的地表能量闭合度,在非均匀下垫面LAS观测优势突出;利用LAS观测的感热通量进行区域陆面模式的验证,能够很大程度地避免EC能量不闭合和空间尺度不匹配在验证中造成的偏差,LAS观测更适合于大尺度模拟的验证,验证效果更好。