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Comparing different post-IR IRSL approaches for the dating of Holocene coastal foredunes from Ruhnu Island, Estonia

Preusser F., Muru M., Rosentau A.

Geochronometria

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2014

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Vol. 41, no. 4

342--351

EN

Different post-IR Infrared Stimulated Luminescence (IRSL) approaches are applied to sediments from a Holocene coastal foredune sequence on Ruhnu Island in the eastern Baltic Sea. The comparison of D e-values and ages determined by the different approaches is complimented by fading and bleaching experiments. The fading experiments imply strong fading of IRSL (50°C) signals and no fading of any of the post-IR IRSL signals, but this is not confirmed by the determined D e-values. In fact, post-IR IRSL (150°C) D e-values agree within errors with those calculated for IRSL (50°C). From the bleaching experiments it is inferred that the higher values observed for post-IR IRSL at more elevated stimulation temperatures (225°C/290°C) are likely related to either thermal transfer and/or slow-to-bleach components within the signal. For the dating of the Holocene foredune sequence of Ruhnu Island, the post-IR IRSL (150°C) approach is preferred and these agree with the limited independent age control available from radiocarbon dating. Accordingly, the sequence formed between ca. 7.0 ka and 2.5 ka ago.

2

Development of the Holocene foredune plain in the Narva-Jõesuu area, eastern Gulf of Finland

Rosentau A., Jõeleht A., Plado J., Aunap R., Muru M., Eskola K. O.

Geological Quarterly

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2013

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Vol. 57, No. 1

89--100

EN

The morphogenesis and inner structure of the Holocene foredune plain in the Narva-Joesuu area, eastern Gulf of Finland, were studied using optically stimulated luminescence (OSL) dating, ground-penetrating radar (GPR) study and interpretation of airborne LIDAR elevation data. The results show that the Narva-Joesuu foredune plain consists of ca. 100 parallel coastal foredune ridges built of well-sorted fine sand underlain by gently (~7°) seaward-dipping sandy beach deposits. The distal part of the plain, which consists of at least 15 ridges, formed during the regressive phase of the Ancylus Lake/Early Litorina Sea, serving as a barrier for the lagoon behind it. A larger portion of ridges, with an average progradation rate of 0.26 m a-1, formed under conditions of falling relative sea level during the Litorina regression and was separated from the older foredune succession by a hiatus related to the Litorina transgression at 8.5-7.3 cal. ka BP. In the highest central part of the plain the foredune growth was interrupted by foredune instability and a re-blowing episode dated to 5.4 ± 0.9 ka BP which may correlate with a larger regional cooling at 5.8-5.1 cal. ka BP in the North Atlantic and central Europe. During the last 3000 years, the foredune progradation rate decreased to 0.19 m a-1, most probably because of decelerated land-uplift and increased human impact due to coastal protection.

3

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.

4

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.

5

Simulation of the shorelines of glacial Lake Peipsi in Eastern Estonia during the Late Weichselian

Rosentau A., Hang T., Miidel A.

Geological Quarterly

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2004

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Vol. 48, No 4

299--307

EN

Digital reconstruction of the evolution of glacial Lake Peipsi, Eastern Estonia, was based on a geographic information system (GIS) method that removed isostatically deformed palaeowater planes fromthe current digital terrain model. A reconstruction of the proglacial water levels was performed with respect to geomorphological correlation of river terraces, raised shorelines and eroded surfaces of various aqueoglacial landforms. The configuration of shorelines, main outlets and water depths of glacial Lake Peipsi, corresponding to the Otepää, Piirissaar, Kaiu and Pandivere–Neva stades during the deglaciation of the Lake Peipsi depression, was simulated. The two approaches used, reflecting the geomorphological correlation of Raukas and Rähni (1969) and Hang (2001), are discussed.