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

Biostratigraphy, shoreline changes and origin of the Limnea Sea lagoons in northern Estonia: a case study of Lake Harku


The paper presents diatom, loss-on-ignition, magnetic susceptibility, and radiocarbon data to reconstruct the depositional history and evolution of Lake Harku, a former Limnea Sea lagoon. Harku is one of the youngest isolated lakes that has been studied bio- and chronostratigraphically in Estonia to date. Based on changes in diatom assemblages, four evolutionary stages in basin development have been recognized (lagoon, semi-enclosed lagoon, transitional and closed lake). Shoreline positions at 2000, 1500, 1000 and 800 cal BP have been reconstructed and displayed on 3D palaeogeographic maps. Lake Harku became isolated from the Limnea Sea at ~800 cal BP, followed by occasional seawater incursions over the next 300 years. Plain landscape, low-lying sill threshold, and proximity to the sea contributed to extended basin isolation.


Keywords diatom, radiocarbon dating, loss-on-ignition, 3D palaeogeographic maps, lake isolation

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