The thermoluminescence (TL) dating of aquatic sand’y sediments, carried out as a cooperation between Gdańsk and Vilnius Universities, provided a more accurate chronology of the Middle-Upper Pleistocene in Lithuania. Based on TL dating, Middle and Upper Pleistocene fine-grained sands of aquatic origin have been attributed to the Butėnai (Holsteinian) Interglacial (Tartokai outcrop), Snaigupėlė (Drenthe–Wartha) Interglacial (Tartokai and Valakampiai (Valakupiai) outcrops), Merkinė (Eemian) Interglacial (Tartokai and Netiesos outcrops) and Nemunas (Vistulian) Glacial (Tartokai, Netiesos and Rokai outcrops). The dating of samples from the outcrops studied show the age of the Butėnai Interglacial to be 430.2 to 280.3 ka years BP, of the Snaigupėlė Interglacial 239.4 to 179.3 ka years BP and the Merkinė Interglacial 135.9 to 103.2 ka years BP. The Early Nemunas and the Middle Nemunas non-glacial sediments accumulated between 67.2–30.6 ka years BP. Tills in the upper part of the Tartokai and Rokai outcrops are younger than 30,000 BP and belong to the Late Nemunas glacial maximum in Lithuania. Different dosimetric (TL, OSL) ages of granular fractions of the same sample indicate different parametres predetermined by the distribution of grain size fractions during aquatic sedimentation of quartz sand. The granulometry of sand or the grain size distribution of quartz particles in samples reflect the state of the hydrodynamic sedimentation space.

Keywords: thermoluminescence (TL) dating, aquatic sediments, Pleistocene, Lithuania, sedimentological interpretation