Palaeoenvironment of the Karelian Isthmus, the easternmost part of the Gulf of Finland, during the Litorina Sea stage of the Baltic Sea history

摘要

The palaeoenvironment of the Karelian Isthmus area during the Litorina Sea stage of the Baltic Sea history, between 8.0 and 4.5 kyr BP ( 8.8 - 5.2 cal. kyr BP), was reconstructed by studying four sites located on the Karelian Isthmus in Russia. Methods included diatom and pollen analyses, sediment lithostratigraphical interpretation and 14 C dating. The brackish- water ( Litorina) transgression began c. 7.7 kyr BP ( 8.45 cal. kyr BP) in the Karelian Isthmus area. The transgression maximum occurred between 6.7 and 5.7 kyr BP ( 7.6 - 6.5 cal. kyr BP), depending on the glacio- isostatic land uplift rate. Regarding the vegetation, the maximum occurrence of temperate deciduous trees took place at the same time. The transgression was interrupted by a short- lived sea- level standstill during the middle phase of the main transgression, c. 6.3 kyr BP ( 7.2 cal. kyr BP), on the eastern part of the isthmus. The highest Litorina shoreline is located between 8 and 13 m above present sea- level and the amplitude of the Litorina transgression has varied between 5 and 7 m. The 8.2- kyr cold event is not evident, but the sea- level standstill around 6.3 kyr BP ( 7.2 cal. kyr BP) could reflect a cool episode at that time in the Karelian Isthmus area.