Age of organic-rich deposits in the Lenenergo section (southeastern Lake Ladoga region)

The Lenenergo section located on the Oyat River left bank in the south-eastern Lake Ladoga region is critical for studying the Holocene transgressions of Lake Ladoga. Uncertainty in the previously published organic-rich deposits age data substantiates the use of paleogeographic methods to reexamine them. The article presents lithological characteristics of the section as well as results of detailed pollen analysis and radiocarbon dating of peat and gyttja. The organic-rich deposits accumulation occurred from 8,900 ± 150 14 C yrs BP (9,960 ± 210 cal BP) to 3,530 ± 80 14 C yrs BP (3,810 ± 110 cal BP). On the territory, the Preboreal period marked peat accumulation and sparse vegetation cover. Gyttja, whose age was 8,420 ± 90 14 C yrs BP (9,400 ± 100 cal BP), accumulated during the Boreal period and was characterized by dominance of pine and birch forests in the environment. The sedimentation hiatus lasting at least 3,500 years was revealed at the turn of the Boreal and Atlantic periods. Gyttja accumulation continued in the conditions of the Lake Ladoga paleolagoon during the Atlantic and Subboreal periods from 4,880 ± 200 14 C yrs BP (5,610 ± 250 cal BP) to 3,530 ± 80 14 C yrs BP (3,810 ± 110 cal BP). Pine, spruce, and birch forests with an admixture of broad-leaved species dominated. Diatom analysis and geochemical studies are projected to fully characterize sedimentation conditions in the southeastern Lake Ladoga region during the Holocene.