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1

Cyclic sedimentation pattern in Lake Veetka, southeast Estonia: a case study

Saarse L.

Geologos

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2015

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Vol. 21, No. 1

59--69

EN

A sediment core from Lake Veetka, southeast Estonia, 1077 cm in length and covering 10,500 calibrated years, was examined using loss-on-ignition, grain-size distribution and AMS 14C dating to reconstruct depositional dynamics. The studied core, recovered from the northern part of the lake, shows a cyclic pattern of organic and mineral matter concentration with cycle durations of 100-400 years. Cyclicity is displayed better in sediments laid down between 9,200 and 5,600 cal BP. Within two time windows (5,600–5,100 cal BP and from 1,200 cal BP to the present), sediment composition changed drastically on account of a high and fluctuating mineral matter content, obviously driven by different factors. Little Ice Age cooling is characterised by the highest proportion of mineral matter, and the Medieval Warm Period is typified by high organic matter content. The cyclic change of organic and mineral matter has been related to climate dynamics, most likely an alternation of wet and dry conditions, changes in the water level of the lake and differences in bioproduction.

2

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

Vassiljev J., Saarse L., Grudzinska I., Heinsalu A.

Geological Quarterly

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2015

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Vol. 59, No. 3

517--530

EN

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.

3

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

Saarse L., Heinsalu A., Veski S.

Geological Quarterly

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2012

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Vol. 56, No 2

353-362

EN

Accelerator mass spectrometry (AMS) 14

4

Postglacial palaeoenvironmental changesin the area surrounding Lake Udriku in North Estonia

Amon L., Saarse L.

Geological Quarterly

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2010

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Vol. 54, No 1

85-94

EN

Multiproxy data (plant macrofossils, AMS 14C radiocarbon dates, grain-size distribution, loss-on-ignition and magnetic susceptibility) from Lake Udriku Suurjärv in North Estonia were used to interpret local environmental changes during the postglacial period between 13 800 and 11 000 cal yr BP. Sediment lithology is complex but can roughly be described as silt overlain by silty gyttja, gyttjaand peat. The macrofossil diagram shows the local vegetation development from Late Glacial pioneer communities to early Holocenecommunities. The vegetation succession started predominately with Salix polaris, which was later replaced by Dryas octopetala. Thediversity of plant macrofossils increased significantly during the warmer part of the Allerod. Both the diversity and the number ofplant macrofossils are low in the Younger Dryas, confirming the severe climatic conditions found during this interval. During the LateGlacial to Holocene transition, aquatic taxa prevail among plant macrofossils. The absence of tree remains among macrofossils of thisperiod suggests that trees were not locally present or were not growing near the studied lake. Proxy data indicate several environmental changes. The sediment composition and vegetation reflect cooler and warmer episodes and confirm that the study area has been freeof ice since 13 800 cal yr BP.

5

Litorina Sea shore displacement on the Island of Saaremaa, Estonia

Saarse L., Vassiliev J., Rosentau A.

Polish Geological Institute Special Papers

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2009

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Vol. 25

59-66

EN

Sedimentological and magnetic susceptibility analyses, and radiocarbon datings of six Holocene sequences (Ohtja, Kihelkonna, Vedruka, Vesiku, Lümanda, Jáempa) were used to elucidate the Litorina Sea development on the Island of Saaremaa, Estonia. The Litorina Sea beach formations are located between 20.5 and 15.5 m above the present day sea level. Spatial distribution of the Litorina Sea shore displacement was reconstructed. The onset of the Litorina Sea transgression in the study area is dated to 8200 cal yr BP. The measure of a single transgression was about 4.5–5.0 m.

PL

Badania sedymentologiczne i analiza podatności magnetycznej oraz datowania radiowęglowe w 6 stanowiskach holoceńskich (Ohtja, Kihelkonna, Vedruka, Vesiku, Lümanda, Jáempa) umożliwiły przedstawienie rozwoju morza litorynowego na wyspie Saaremaa w Estonii. Formacje plażowe morza litorynowego występują na wysokości od 20,5 do 15,5 m n.p.m. Zrekonstruowano położenie brzegu morza litorynowego. Początek transgresji morza litorynowego określono na 8200 lat kalendarzowych. Wielkość pojedynczej transgresji wynosiła około 4,5–5,0 m.

6

Proglacial lake shorelines of Estonia and adjoining areas

Rosentau A., Vassiliev J., Saarse L., Miidel A.

Polish Geological Institute Special Papers

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2008

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Vol. 23

81-86

EN

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.

7

Fine-resolution pollen-based evidences of farming and forest development, South-Eastern Estonia

Niinemets E., Saarse L.

Polish Journal of Ecology

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2007

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Vol. 55, nr 2

283-296

EN

The pollen stratigraphical and lithological data obtained from Lake Lasva, southern Estonia, are summarized. The land-use and vegetation history during the last 6300 years in an agricultural area with dense prehistoric setting is discussed. A high sedimentation rate and laminated structure of lake deposits enabled high-resolution palaeobotanical study of a 985 cm long core. Accelerator mass spectrometry [^14]C dates show good linearity and fit well with varve counts. Up to ca 2900 years BP, birch, pine, spruce and broad-leaved species, later mostly birch, pine and alder, grew in that area. The first weak signs of human impact were traced at 6300 years BP. Human activities were more pronounced be.tween 5400-5100 and 3800-3500 years ago, due to the foundation of Neolithic settlements not far from the lake. The first attempt of small-scale tillage, detected from the first finds of Triticum pollen, followed by a long-term gap, dates back to 5100 years BP. Crop cultivation (Cannabis, Hordeum, Triticum and Secale) became the main means of subsistence not until the Iron Age at about 1600-1400 years ago, but extensive arable farming started to develop 800 years ago, after the German crusaders invaded the area. Pollen dia.grams display several setbacks in arable farming, mostly caused by crop failure due to climate de-terioration and decrease in the population caused by famines, wars and epidemics.

8

Simulation of proglacial lake shore displacement in Estonia

Vassiljev J., Saarse L., Miidel A.

Geological Quarterly

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2005

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Vol. 49, No. 3

253-262

EN

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.