Relative sea-level variations indicated by micropaleontological data from small lake bottom sediments (Kandalaksha Bay, NW Russia)

Аннотация

The results of the micro-paleontological study of bottom sediments from a small lake on the Kandalaksha Bay shore of the White Sea are reported. Three stages in the evolution of the lake basin: marine, transitional and lacustrine were recognized. The characteristics of their diatom complexes and palynological spectra were revealed. Marine-facies sediments were shown to be dominated by poly- and mesohalobes, their share in the transition facies is twice as small, and freshwater diatom complexes contain up to 10% halophiles. Facies were shown to be reliably identified, using the pollen and spores of distinctive species indicative of certain ecological conditions. Non-pollen palynomorphs (algae Pediastrum, Botryococcus and sponge spicules) can be used for identifying various facies. These data will be used later to more reliably and objectively reconstruct variations in relative sea level and the sea shoreline migration in the Holocene. A decrease in sea level was  established at the turn of 7200 cal. years and the isolation of the lake from the sea occurred about 6700 cal. years ago.