Retreat of the southern front of the last Scandinavian Ice Sheet: dates and rates

• Main Authors: Tylmann, Karol, Rinterknecht, Vincent, Woźniak, Piotr, Bourlès, Didier, Schimmelpfennig, Irene, Guilou, Valery
• Other Authors: Faculty of Oceanography and Geography, University of Gdansk
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDE]Environmental Sciences; Ice Sheet
• Online Access: https://hal.archives-ouvertes.fr/hal-03546914

International audience The last Scandinavian Ice Sheet (SIS) in northern Europe was one of the major NorthernHemisphere ice-sheets of the last glacial cycle. The southern fringe of the last SIS located to the south of the Baltic Basin reached its last maximum extent during the Late Weichselian, around 24–19 ka, and retreated gradually with episodes of regional and local ice readvances. The timing of the last SIS retreat reflects the Late Weichselian climate fluctuations, as well as the internal dynamics of the ice-sheet controlled largely by activation and deactivation of ice streams. Here, we present new results of erratic boulders dating with in-situ cosmogenic nuclides from the southern sector of the last SIS. This new data set compiled with already published but recalculated 10Be surface exposure ages, as well as OSL/14C ages available in the literature, enabled to explore the timing of the last SIS maximum expansion and retreat with respect to the climate fluctuations during the Late Weichselian.The new 55 10Be ages and one 36Cl age come all from erratics located in-situ on glaciallandforms in NW Poland, and were compiled with 20 already published 10Be ages recalculated according to the most recent 10Be production rate. The full surface exposure age data set is interpreted as representing the initiation of the ice sheet retreat at the termination of specific glacial phases during the Late Weichselian. The error-weighted mean ages of the ice margin retreat for the Brandenburg, Frankfurt and Pomeranian Phases are calculated at 21.6 ± 1.0 ka, 18.2 ± 0.6 ka and 17.2 ± 0.4 ka respectively. Based on these results and their correlation with independent age constraints (14C ages of organic deposits and OSL ages of sand deposits intercalated in tills deposited by the last SIS), the age of the maximum ice sheet limits during the Brandenburg, Frankfurt and Pomeranian Phases may be estimated at ~23.0 ka, ~20.0 ka and ~17.5 ka respectively.The available geochronological data (cosmogenic nuclides, 14C and OSL ages) ...