Karol Tylmann , Szymon Uścinowicz

A new chronology of the last Scandinavian Ice Sheet retreat in the southern Baltic basin is proposed. Based on Bayesian age modeling, we show that the most likely ages of particular deglaciation phases are 16.5 ± 0.5 ka for the Gardno Phase, 15.6 ± 0.6 ka for the Słupsk Bank Phase, and 13.9 ± 0.5 ka for the Southern Middle Bank Phase. The Gardno moraines are correlated with the Halland Coastal moraines in southern Sweden and the Middle Lithuanian moraines in Lithuania and Latvia. Ice margin stillstands of the Słupsk Bank Phase and Souhern Middle Bank Phase are correlated with the Göteborg and Vimmerby moraines, and with the North Lithuanian (Haanja) and Otepää moraines. The average retreat rates of the ice margin of about 55 m/yr between the Gardno Phase and the Słupsk Bank Phase, and about 40 m/yr between the Słupsk Bank Phase and the Southern Middle Bank Phase suggest that the last deglaciation did not accelerate after the Gardno Phase when an extensive ice-dammed lake was formed in front of the retreating ice sheet. The ice margin was probably grounded rather than floating, which prevented its more rapid retreat. The timing of the two main ice margin stillstands at the Słupsk Bank and at the Southern Middle Bank corresponds to the cool periods around 15 and 14 ka interpreted from paleotemperatures of Greenland based on ice core GISP2. This suggests that the main phases of the last deglaciation in the southern Baltic region were at least partly triggered by climatic fluctuations in the Northern Hemisphere.