Lithological and geochemical analyses of sandy beach sediments of different geological frameworks: the south-eastern Baltic Sea (Lithuania)

Abstract

This study aims to analyse the spatial lithological and geochemical composition of beach sediments from two sites representing coastal areas with different geological and geomorphological frameworks, sediment availability and sediment transport pathways. The sandy beach surface sediments were sampled in spring 2018, the magnetic susceptibility was measured on-site and the grain size analysis was carried out and the geochemical composition of the samples determined in the laboratory (ICP-MS/ES). The results indicated that even though the sites differed in term of geology and geomorphology, the mean magnetic susceptibly and grain size did not differ significantly. On the contrary, the two sites showed significant differences in elemental composition. The factorial analysis revealed that there were two main groups of elements; the first was composed of Fe–V–Cr–Pb–As–K–Co–P–Ni–Al–Ga, mostly represented in the sediments of the Curonian Spit, and the second group was composed of Mn–Ca–Mg–Sr–Ti–Ba which defined the composition of the sandy beach sediments of the mainland coast. We interpreted the geochemical anomalies as having different causes. On the mainland coast, geochemical and lithological anomalies tend to form where the coastal erosive processes are active, while on the Curonian Spit, these anomalies are located where relict coarse sand dominates and the main unloading of sediments from the alongshore northward current occurs. These results allow the sediment transport process to be better understood and the sediments’ provenance to be identified. In the future, they could also be used for coastal sediment transport modelling exercises.