Weichseli jäätumise kronoloogia Skandinaavia jäätumise kagusektoris

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Doktoritöö uurib Weichseli jäätumise ajalist kulgu, liustiku maksimaalse leviku ulatust ja liustiku pealetungi ja taandumise dünaamikat Ida-Euroopa tasandiku lääneosas. Uuringuala hõlmab Skandinaavia jäätumise kagusektorit Läänemerest kuni viimase jäätumise maksimaalse leviku piirini. See ala on Weichseli jäätumise jooksul mitmeid kordi allunud liustike tegevusele. Varasemate liustike ajalis-ruumilise dünaamika välja selgitamine on oluline, et ennustada praegu eksisteerivate liustike reageerimist järjest soojenevale kliimale. Varasemate liustike dünaamikat saab välja selgitada kronoloogiliste uuringute abil, mis on ka käesolev doktoritöö teemaks. Teadmised Weichseli jäätumise ajalis-ruumilise kulgemise kohta Ida-Euroopa tasandikul on vaatamata mitmekülgsetele uuringutele väga lünklikud ja olemasolevad andmed jäätumisala lõikes ebaühtlased. Eriti puudulik info on varasemate Vara- ja Kesk-Weichseli jäätumise kohta, kuna sellele järgnenud Hilis-Weichseli liustik on varasemaid setteid ja pinnavorme oluliselt ümber kujundanud või hoopis erodeerinud. Seetõttu on varasemate jäätumiste setteid Põhja-, Kesk- ja Ida-Euroopast leitud vaid üksikutest kohtadest. Viimase, Hilis-Weichseli jäätumise kohta on andmeid rohkem, kuid siiani on ebaselge liustiku saabumise aeg uuringualale ja laienemine maksimaalse leviku piirile. Samuti on viimase liustiku taandumise käik olnud põnevate diskussioonide teemaks. Doktoritöö eesmärgiks on koondada ja kriitiliselt analüüsida Weichseli jäätumise liustike dünaamikat iseloomustavat kronoloogilist andmestikku Ida-Euroopa tasandiku lääneosas. Detailsemad andmed esitatakse viimasele jäätumisele eelnenud jäävaba perioodi kestvuse kohta uuringualal; hinnatakse viimase Weichseli liustiku pealetungi ja selle maksimaalse leviku ajalist kestvust; esitatakse viimase jäätumise taandumise kronoloogia arvestades andmestiku geograafilise paiknemise ja liustikukeelte dünaamikaga ning diskuteeritakse liustiku pealetungi ja taandumise kiiruse üleThis thesis examines the chronology of Weichselian Glaciation, maximum extent of Scandinavian Ice Sheet (SIS) and its glacial advance and decay dynamics in western part of the East European Plain (EEP). Knowledge about temporal and spatial dynamics of former ice sheets would allow us to predict the response of current glaciers to globally warming climate. The study area of the thesis encompasses the SE sector of the SIS between the Baltic Sea and the Last Glacial Maximum (LGM) position in the western part of the EEP. The Weichselian Glaciation is most extensively studied; however chronological data are unevenly distributed. Still, the occurrence of Early to Middle Weichselian glaciation in this region remains controversial because the advancing ice sheet has a great destructive potential for soft unconsolidated sediments and most of the sediments of former glaciations have been removed. However, evidence of glacial sediments attributed to the Middle Weichselian has been found in several sites in Europe, although, the opinions about the extent of SIS during the Middle Weichselian glaciation have remained contradicting. More is known about the last glaciation, but the timing of the advance of the last SIS and its arrival to maximum extent and deglaciation are continuously debated. This has necessitated the revision of the chronological data. In current thesis the behaviour of the SIS during the Weichselian Glaciation on EEP is discussed through the collection, review and synchronization of all available chronological data. In detail the duration of the ice-free period before the last glaciation is determined; an overall chronology for the last SIS advance is established; deglaciation chronology in conjunction with the current understanding of the ice-flow pattern is defined and overall rates of ice-sheet advance and recession are discussed

Geological settings of the protected Selisoo mire (northeastern Estonia) threatened by oil shale mining

The protected Selisoo mire in northeastern Estonia is located above valuable oil shale resources, partly in the permitted mining area. We describe in detail the geomorphology and geological setting of the mire to understand the natural preconditions for its formation, development and preservation. We used the LiDAR-based digital elevation model for relief analysis, mapped the peat thickness with ground-penetrating radar and described the Quaternary cover through corings. Ridges, oriented perpendicular to the generally southward-sloping terrain, and shallow depressions at the surface of mineral soil have influenced mire formation and its spatio-temporal dynamics. The Quaternary cover under the mire is thin and highly variable. Therefore the mire is hydro­geologically insufficiently isolated from the limestone bedrock that is drained by the nearby oil shale mine and consequently the mining activities approaching the mire may have a negative influence on the wetland and proposed Natura 2000 site. Natura 2000 type wetlands, both protected or currently outside the nature reserves, cover a significant portion of the prospective oil shale mining areas. The distribution and resilience of those sites may significantly influence further utilization of oil shale resources

Palaeoclimate inferred from δ18O and palaeobotanical indicators in freshwater tufa of Lake Äntu Sinijärv, Estonia

We investigated a 3.75-m-long lacustrine sediment record from Lake Äntu Sinijärv, northern Estonia, which has a modeled basal age >12,800 cal yr BP. Our multi-proxy approach focused on the stable oxygen isotope composition (δ18O) of freshwater tufa. Our new palaeoclimate information for the Eastern Baltic region, based on high-resolution δ18O data (219 samples), is supported by pollen and plant macrofossil data. Radiocarbon dates were used to develop a core chronology and estimate sedimentation rates. Freshwater tufa precipitation started ca. 10,700 cal yr BP, ca. 2,000 years later than suggested by previous studies on the same lake. Younger Dryas cooling is documented clearly in Lake Äntu Sinijärv sediments by abrupt appearance of diagnostic pollen (Betula nana, Dryas octopetala), highest mineral matter content in sediments (up to 90 %) and low values of δ18O (less than −12 ‰). Globally recognized 9.3- and 8.2-ka cold events are weakly defined by negative shifts in δ18O values, to −11.3 and −11.7 ‰, respectively, and low concentrations of herb pollen and charcoal particles. The Holocene thermal maximum (HTM) is palaeobotanically well documented by the first appearance and establishment of nemoral thermophilous taxa and presence of water lilies requiring warm conditions. Isotope values show an increasing trend during the HTM, from −11.5 to −10.5 ‰. Relatively stable environmental conditions, represented by only a small-scale increase in δ18O (up to 1 ‰) and high pollen concentrations between 5,000 and 3,000 cal yr BP, were followed by a decrease in δ18O, reaching the most negative value (−12.7 ‰) recorded in the freshwater tufa ca. 900 cal yr BP

Eesti maapõue kirjeldamise standardiseerimine.

Üleminekuga digitaalsele geoloogilisele kaardistamisele astuti Eestis oluline samm lähemale maapõue 3D mudelite süstemaatilise kasutamise suunas. Kogu Eestit käsitlevate mudelite koostamine peaks põhimõtteliselt tuginema puursüdamike andmebaasis talletatud informatsioonile. Maapõue kirjeldamine on Eestis reguleeritud geoloogilise kaardistamise juhendmaterjalidega, mida on väikeste muudatustega rakendatud alates aastast 2004. Käesoleva projekti eesmärgiks oli kasutatava kaardistuslegendi ning kaardistusandmebaasi sisu kriiline analüüs ning kaardistuslegendi uuendamise ettepanekute väljatöötamine. Aruanne koosneb käesolevast kokkuvõttest ja selle kuuest lisast, milles esitatakse tööprotsessi kirjeldus, projekti põhitulemused ning neil põhinevad kaardistuslegendi uuendamise ettepanekud

Ice-free interval corresponding to Marine Isotope Stages 4 and 3 at the Last Glacial Maximum position at Kileshino, Valdaj Upland, Russia

Radiocarbon and optically stimulated luminescence dates, together with bio- and lithostratigraphical data, revealed an interval of ice-free conditions between 72.2 OSL and 33.8 cal 14C ka BP at the Kileshino site (Valdaj Upland, Russia), corresponding to Marine Isotope Stages (MIS) 4 and 3. Limnic sedimentation conditions occurred at the Kileshino site between 57.5 OSL and 33.8 cal 14C ka BP, corresponding to MIS 3 ‘megainterstadial’ in European Russia (Oerel to Hengelo interstadials in Central Europe). During the last glaciation, a sedimentary unit of laminated silt and sand of fluvial origin was redeposited at that site due to expansion of the Scandinavian Ice Sheet (SIS). This unit expresses fluvial sedimentation conditions NW of Kileshino between 72.2 and 40.8 OSL ka. All dates together suggest that the Kileshino site was ice-free between 72.2 OSL and 33.8 cal 14C ka BP. The sedimentary unit of laminated silt and sand was redeposited at the Kileshino site during the last SIS not before 33.8 cal 14C ka BP, according to previous studies, possibly at its maximum extent between 19.1 cal 14C BP and 18 OSL ka. Only one till, younger than 72.2 ka, was found from the Kileshino outcrop. It can be concluded that the SIS reached this area only once during the last 72.2 ka – in the late Valdaj (Weichselian), after 33.8 cal 14C ka BP. The expansion of the SIS to the study area between 115 and 58 ka could be neither proved nor disproved as there is no chronological information about the time between 115 and 72.2 ka

Biostratigraphic evidence relating to the age-old question of Hannibal's invasion of Italy, I: history and geological reconstruction

Open access article. Creative Commons Attribution 4.0 International License (CC BY 4.0) appliesControversy over the alpine route that Hannibal of Carthage followed from the Rhône Basin into Italia has raged amongst classicists and ancient historians for over two millennia. The motivation for identifying the route taken by the Punic Army through the Alps lies in its potential for identifying sites of historical archaeological significance and for the resolution of one of history's most enduring quandaries. Here, we present stratigraphic, geochemical and microbiological evidence recovered from an alluvial floodplain mire located below the Col de la Traversette (~3000 m asl—above sea level) on the French/Italian border that potentially identifies the invasion route as the one originally proposed by Sir Gavin de Beer (de Beer 1974). The dated layer is termed the MAD bed (mass animal deposition) based on disrupted bedding, greatly increased organic carbon and key/specialized biological components/compounds, the latter reported in Part II of this paper. We propose that the highly abnormal churned up (bioturbated) bed was contaminated by the passage of Hannibal's animals, possibly thousands, feeding and watering at the site, during the early stage of Hannibal's invasion of Italia (218 bc).Ye