A palaeocoastline reconstruction for the Käsmu and Pärispea peninsulas (northern Estonia) over the last 4000 years

Abstract

The marine-freshwater environmental transition, i.e. basin isolation from the Limnea Sea, has been identified in two short sediment cores with respect to their diatom composition, loss-on-ignition and magnetic susceptibility content. The isolation level of the basins was dated by accelerator mass spectrometry radiocarbon measurements. The basins are situated on the southern coast of the Gulf of Finland between altitudes 5.5 and 3.9 m above sea level. The Lohja basin became isolated from the sea around 2300 cal yr BP and Käsmu basin around 1800 cal yr BP as a result of glacio-isostatic uplift. The total land upheaval rate that has been 2.6 mm yr –1 since 2500 cal yr BP has currently decreased to 2.0 mm yr –1. We present a GIS-based 3D palaeogeographic reconstruction of the palaeocoastline changes in northern Estonia for two peninsulas, Pärispea and Käsmu, as well as compose a shoreline displacement curve for the study area, which is a compilation of previous and ongoing investigations

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

“…How ever, un like at Loopsoo and Prassi, the tran si tion zone from a la goon to a fresh wa ter ba sin in Tihu is marked by a peak of small-sized fragilarioid taxa (Fig. 3C), in dicat ing a change in depositional en vi ron ment (Seppä and Tikkanen, 1998;Seppä et al, 2000;Risberg et al, 2005;Grudzinska et al, 2012Grudzinska et al, , 2013. Sand re place ment by coarse de tri tus gyttja marks the iso la tion con tact at 191 cm and is in ac cor dance with a change in di a tom as sem blage from ma rine/brack ish-wa ter taxa to fresh wa ter taxa (Fig.…”

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

“…3C) Post-isolation sediments are characterised by the predominance of planktonic freshwater Aulacoseira species. The most common diatom Aulacoseira subarctica is meroplanktonic and is only present in the water column when there is sufficient turbulence (Gibson et al, 2003), therefore the distinct increase in planktonic diatoms is not related to the lake level rise, but can instead be explained by the location in an open landscape close to a windy sea coast (Grudzinska et al, 2012), where the exposure to wind-induced waves resulted in the turbulent mixing of the water column. Lake Käsmu lithostratigraphy is rather similar to Lohja site, however, the Käsmu core also includes a sand layer (Kä-3), imbedded into silt (Kä-2, Kä-4; Table 3).…”

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

“…Similar changes in the trophic state have been observed in many isolation basins (e.g. Grudzinska et al 2012;Seppä, Tikkanen 1998;Westman, Hedenström et al 2002;Yu et al 2004). The enhanced nutrient content in Lake Harku could be explained by two factors: 1) occasional mixing of brackish and fresh water that promotes biological productivity and enrichment with organic compounds (Head 1976, cited after Bechtel et al 2007, and 2) an intense nutrient input from the sparsely vegetated catchment area (Seppä et al 2000).…”

“…To date, the biostratigraphy and shoreline changes of the Limnea Sea are poorly documented in Estonia. Only two lakes in northern Estonia, which became isolated during the Limnea Sea phase, have been studied bioand chronostratigraphically (Grudzinska et al 2012). Lake Harku presents a good setting for reconstructing coastal evolution in this region due to fast sedimentation rate (Saarse 1994), which improve the temporal resolution (Fig.…”