As early as in the 1960s, extensive heavy-mineral concentrations containing zircon, monazite, and xenotime were discovered in the Lemme region of south-western Estonia. These concentrations contribute to the elevated radioactivity levels of the enclosing sediments. The near shore sands of the Litorina Sea contain up to 10-cm-thick interlayers with a heavy mineral content of up to 80%. These anomalous layers were formed during the transgressive phase and result from a complicated cross-and alongshore migration of sedimentary material, derived mainly from local Devonian bedrock. Radioactivity level in the study area is higher relative to the majority of the Devonian plateau. The Lemmeoja buried soil has 13 radiocarbon dates in an area of renewed interest for the investigation of the Baltic Sea history.

The Baltic Sea is characterised by tectonic conditions that cause its northern parts to lift and southern parts to sink. Our study area (eastern coast of the Gulf of Riga) has been rather stable for a long time. During transgressive phases in the course of the sea's invasion to the coast intensive mechanical and mineralogical differentiation of the sediments took place, causing the separation of heavy minerals. The largest concentrations of heavy minerals were found in transgressive sediments of the Litorina Sea. Their concentration was especially high in the Lemmeoja site (in some layers up to 83.7 % of the sediment). The goal of our research was to study the heavy mineral content and composition in different age sediments of the area and to find regularities in the accumulation processes through time. To achieve our aim we collected samples from 16 sites between Pärnu and Ikla in south-western Estonia. The heavy mineral content in the whole investigated area is high, amounting on average to about 5 %. The deposits of transgressive phases of the Baltic Sea are more reworked than those of the regressive phases and contain more heavy minerals. Our investigation of initial rocks allows to conclude that garnets and zircon originated mainly from the Devonian sandstones of the Aruküla and Narva regional stages, amphiboles and pyroxenes mainly from Quaternary deposits.Keywords (GeoRef Thesaurus, AGI): transgression, sea-level changes, heavy minerals, Baltic Sea, Gulf of Riga * Corresponding author e-mail: iisebel@hotmail.com AbstractAccumulation of heavy minerals in the eastern coast of the Gulf of Riga, south-western Estonia

The present study discusses results of heavy mineral analyses and radioactivity of beach sediments of Lake Peipsi. Such analyses are commonly done globally, but had not yet been conducted for the fourth largest lake in Europe. The average heavy mineral content in Lake Peipsi beach sediments along the northern and western coast is higher than usual for Estonian coastal and Quaternary sediments. Concomitantly, elevated radioactivity levels have been measured in several places, with the highest concentrations observed at Alajõe (1885.5 Bq/kg), which is over five times more than the recommended limit. The aim of the present study is to find sites with higher radioactivity levels, because the northern coast of Lake Peipsi is a well-known recreational area.

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Narva-Jõesuu lies at the eastern southeastern coast of the Gulf of Finland, at the Estonian and Russian border. The beach is influenced by heavy winds, waves and drift ice attacks, which are seriously changing the beach. It is the longest sandy beach in Estonia and longshore drift on this beach has induced favorable conditions for the separation of heavy minerals. The aims of the study were to describe the development of the coast, discuss the influence of the destructed pier, and to identify the mineral composition of beach sands. The dynamics of the coast were mainly through comparison with older topographic maps (from the beginning of the 20th century). For mineral analysis the immersion method was applied. The heavy mineral content was found to increase from east to west. The pier was built in Narva-Jõesuu in 1987/88 for protecting the coast, but it is now broken. Consequently, storms are crashing against the coast and erosion of the sandy shore has started. Therefore, the pier should be restored to avoid further beach destruction.