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

Simulation of proglacial lake shore displacement in Estonia

The Late Glacial shoreline database compiled for Estonia covers 149 sites on the proglacial lakes A1 (Voose) and A2 (Kemba). Eighty-two sites were used in further simulations. Point kriging interpolation with a linear trend approach was applied to create interpolated surfaces of water levels for checking the spatial correctness of data. The sites with altitudes visually not matching with sites nearby were discarded, as well as those with residuals of more than 1 mand 0.7 mrespectively. The final surfaces were analysed geostatistically by simulating isobases, direction of tilting, and shoreline gradient. The simulated isobases suggest that both proglacial lakes A1 and A2 were connected with the glacial lake in the Lake Peipsi basin. The interpolated surface aspect shows that the direction of tilting varies between 320° and 340°. The surface gradient of lake A1 is highest in the NW and SE parts of the study area (50 and 25 cm km-1, respectively), and that of lake A2 is highest in the NWand SE parts (40 and 20 cm km-1, respectively). Using the modelling data, the shoreline correlation between the two proglacial lakes has been revised

Deglaciation chronology of the Pandivere and Palivere ice-marginal zones in Estonia

Accelerator mass spectrometry (AMS) 1

Proglacial lake shorelines of Estonia and adjoining areas

A uniform database of the proglacial lake coastal landforms of Estonia, Latvia and NW Russia was created and used to reconstruct the spatial distribution of proglacial lakes using the kriging point interpolation and GIS approaches. Correlation of the Late Glacial coastal landforms confirms that the proglacial lake stage A1 in Estonia is synchronous with the BglI level in Latvia and with one level in NW Russia of undefined index. Proglacial lake A1 was formed concurrently with the Pandivere-Neva ice-margin about 13,300 cal. yrs BP. Proglacial lake A2 level formed probably about 12,800 cal. yrs BP and correlates with the level of BglII in Latvia and GIII in NW Russia. Simulated isobases of proglacial lake water-levels show a relatively regular pattern of the land uplift along the eastern coast of the Baltic and in the northern part of the Lake Peipsi basin, with a steeper tilt towards the northwest. Isobases in the southern part of the Lake Peipsi basin are curving towards SE and are up to 14 m higher than expected from the regional trend. This phenomenon can reflect the forebulge effect during the deglaciation and its later collapse. Shoreline reconstruction suggests that proglacial lakes in the Peipsi and Baltic basins were connected via strait-like systems and had identical water levels. Our reconstructions also show that after the glacier halted at the Pandivere-Neva ice margin about 13,300 cal. yrs BP, there was a connection with the initial Baltic Ice Lake in the west of the Gulf of Riga

Mid- and late-Holocene shoreline changes along the southern coast of the Gulf of Finland

In response to glacio-isostatic rebound in Estonia, a relative sea level fall occurred during the mid- and late-Holocene, and as a result, lowland regions in northern Estonia have experienced an evolution from sea to land. The mid- and late-Holocene shoreline changes along the southern coast of the Gulf of Finland were reconstructed, using litho-, bio- and chronostratigraphical proxies from four lakes. The lakes are located within the Gulf of Finland drainage system at different altitudes between 18 and 4 m above the present sea level. The isolation from the sea and the onset of freshwater lacustrine sedimentation occurred in Tänavjärv basin at 5400 cal yr BP, in Klooga basin at 4200 cal yr BP, in Lohja basin at 2200 cal yr BP and in Käsmu basin at 1800 cal yr BP. Through the application of GIS-based analysis, a modern digital terrain model and reconstructed past water level surfaces, we present a series of scenarios of shoreline and palaeogeography changes occurring since 7800 cal yr BP. The land uplift rate, which was approximately 2.8 mm yr-1 7800 cal yr BP in the surroundings of Tänavjärv, has decreased to 2.2 mm yr-1 at present and that at Lohja from 2.4 to ca 2.0 mm yr-1, respectively. The relative sea level curves show a land uplift decrease, which is nearly linear since the mid-Holocene

Relative sea level changes and development of the Hiiumaa Island during the Holocene

Three sediment cores (Loopsoo, Tihu, Prassi) from Hiiumaa Island (Estonia) were investigated using diatoms, lithological proxies, magnetic susceptibility, geochronological dates and incorporated with the previously studied Kõivasoo site, aiming to reconstruct the development of the island and shoreline changes during the Litorina Sea and the Limnea Sea. The highest level of the Litorina Sea shoreline near Kõivasoo is at 27.6 m a.s.l., and it occurred during the Initial Litorina Sea. Within the Litorina Sea transgression, 7800 cal yr BP, relative sea level reached 24.9 m a.s.l. at Kõivasoo, 24.1 m a.s.l. at Loopsoo, 23.6 m a.s.l. at Tihu, and 21.5 m a.s.l. at Prassi. Kõivasoo became isolated from the sea about 8500 cal yr BP, Loopsoo between 7100 and 6800 cal yr BP, Tihu around 4800 cal yr BP, and Prassi about 2500 cal yr BP. Presently gained data from Hiiumaa Island confirm that the Litorina Sea regressed consistently during the last 8000 years due to progressively declining isostatic rebound. The present study is also illustrated by 3-dimensional palaeogeographic maps of the Hiiumaa Island development

The biostratigraphy of sediments deposited in the Lake Kaali meteorite impact structure, Saaremaa island, Estonia

The results of lithological, biostratigraphical and chronostratigraphical studies on the Lake Kaali meteorite impact structure, Estonia (lat 58°22' N, long 22°40' E) are discussed. Two pollen diagrams and 18 radiocarbon dates from different materials are presented. Due to the small area and deep slopes, Lake Kaali bottom sediments are mixed with allocthonous mineral matter, humus, plant remnants and woody pieces. Pollen records (the extraordinarily high value of Betula pollen in the lowermost spectra, the low Picea pollen frequency and the Quercus pollen maximum) indicate that the meteorite impact catastrophe occurred at about 4000 BP. Soon afterwards the crater ring wall was inhabited by Bronze Age man. At about 2900‒2500 BP, the crater lake dried out and the formation of gyttja was replaced by woody peat accumulation. A return to deepwater conditions at the end of the Early Subatlantic chronozone is marked by deposition of clayey calcareous gyttja

On the deglaciation chronology of the Palivere ice-marginal zone, northern Estonia

This paper presents new bio-, litho- and chronostratigraphical evidence from two adjacent sediment sequences of the Tõdva and Saku basins, northern Estonia that refine the age estimate of the Palivere ice-marginal zone and the deglaciation history of Estonia. Previous palynological studies demonstrated the presence of late-glacial sediments in the area; however, those sections were not dated, and their ages were poorly constrained. New accelerator mass spectrometry (AMS) 14C dates show that sedimentation in the Tõdva basin started at approximately 13 200 cal yr BP. Therefore, because the studied sites are located at the distal part of this zone, we infer that this age represents the minimum timing of the ice retreat from the Palivere ice-marginal zone