Timing of the last deglaciation in Lithuania

Boulders from the Grūda Moraine, which is associated with the maximum extent of the Scandinavian Ice Sheet (SIS) during the last glaciation, and the Baltija (also referred to as the South Lithuanian), the Middle and North Lithuanian moraines, which are associated with recessional stages of the SIS, were sampled for surface exposure dating using ¹⁰Be. By combining these data with existing radiocarbon ages, we developed a chronology for the retreat of the SIS margin in Lithuania. Our new ¹⁰Be ages suggest that the SIS margin began to retreat from its maximum extent at 18.3 ± 0.8 ¹⁰Be kyr. Based on a probable correlation of the Baltija Moraine with the Pomeranian Moraine in Poland, we infer that the Baltija Moraine was formed following a re-advance of the SIS margin. The ice margin retreated from the Baltija position at 14.0 ± 0.4 ¹⁰Be kyr. The SIS-margin retreat paused at least two more times to form the Middle Lithuanian Moraine at 13.5 ± 0.6 ¹⁰Be kyr and the North Lithuanian Moraine (tentatively correlated to the Pajūris Moraine) at 13.3 ± 0.7 ¹⁰Be kyr. Subsequent ice-margin retreat from the North Lithuanian Moraine represented the final deglaciation of Lithuania. Direct dating of these moraines better constrains the relation of ice-margin positions in Lithuania to those in adjacent countries as well as the SIS response to climate change.     

Sedimentary record and luminescence chronology of the Lateglacial and Holocene aeolian sediments in Lithuania

Sand dunes are common along the sea coasts of Lithuania and in some regions of the mainland part of the country. Until recently, the age of the aeolian deposits was only approximate because of the lack of radiocarsbon-dating of soils buried in dune deposits. A relatively new alternative method to direct dating of organic-free deposits is infra-red optically stimulated luminescence (IR-OSL). Using this method, we investigated the sedimentary history of some Lateglacial and Holocene depositional sites of Lithuanian dunes. The samples for IR-OSL dating have been taken from boreholes (Mančiagirè, Smalininkai, Žalioji Giria) and outcrops (Mančiagire and Ventes Ragas) in different dune massifs. The results indicate that the aeolian sedimentation in Lithuania started during the Younger Dryas. The termination of the aeolian processes in the continental part of Lithuania is correlated with the end of the Atlantic or the beginning of the Subboreal period; this can be explained by significant climatic changes during the Atlantic period. There were several periods of high aeolian activity during the Holocene, but these are asynchronous in different dune massifs and variations in the sedimentation rate occurred both vertically over the section and spatially across the massif.