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1 2005

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Middle pleistocene stratigraphy in the light of data from the vilkiskes site, eastern Lithuania

Satkunas J., Molodkov A.

Polish Geological Institute Special Papers

2005

Vol. 16

94--102

The Vilkiskes outcrop is approximately 40 metres high section of Quaternary sandy sediments, exposed in the slope of the Neris River valley and is located 15 km upstream from the city of Vilnius. The section is composed mainly of sand with one till layer in the middle part. The outcrop is of particular interest due to typical section of sandy formation presumably of lacustrine origin, occurring under the till. This formation is widely distributed in the vast area in between Vilnius city and Nemencine town, according to the data of geological mapping, and represents a particular period of nonglacial sedimentation of Saalian time. The new optically stimulated luminescence (OSL) dates (determined by A. Molodkov), obtained from the Vilkiskes section, fall into the time span of 307-230 and 147-137 ka. The age of the lower part of Vilkiskes lacustrine section (dated 307-230 ka by OSL) looks closest to the two ice free stages, which can be correlated with oxygen isotope stages (OIS) 7 (236-186 ka) and OIS 9 (328-301 ka). Ages of about 147.1 and 136.7 ka are obtained near the immediate contact with the underlying glacial lithocomplex. Assuming OSL ages, conditions of occurrence and palaeopalynological characteristics, the interval of the Vilkiskes outcrop with OSL dates falling into the time span 236-186 ka (OIS 7) can be introduced as the last Middle Pleistocene (Drenthe-Warthe) ice free interval in Lithuania, most probably, separating the Zemaitija and Medininkai stadials. The interval dated 147.1 and 136.7 ka is interpreted as the Pamarys Interstadial that tentatively can be correlated with the Zeifen Interstadial in the Kattegat Depression suggesting the existence of a ?Younger Dryas?-type climate oscillation just prior to the OIS 6/5e boundary.