A new Early-Middle Weichselian palaeoenvironmental record from a lacustrine sequence at Svirkanciai, Lithuania

Satkunas, J., Grigiene, A., Buynevich, I. V. & Taminskas, J. 2013 (January): A new Early-Middle Weichselian palaeoenvironmental record from a lacustrine sequence at Svirkanciai, Lithuania. Boreas, Vol. 42, pp. 184-193. 10.1111/j.1502-3885.2012.00280.x. ISSN 0300-9483. The Middle Weichselian (OIS 4-3) and the transition from Early to Middle Weichselian are the most problematic and disputed time intervals of the Late Pleistocene with regard to the palaeogeography of the Fennoscandian glaciations. The number of sites with sediments of Middle Weichselian age in the Baltic region is very limited. An extensive area (77 km(2)) of lacustrine sediments (sand, clay, silt with humus and interlayers of peat), under the relief-forming Upper Weichselian till, was discovered in the vicinity of the Venta settlement, northwestern Lithuania, and named the Venta Palaeolacustrine Basin. The Svirkanciai outcrop (56 degrees 18'05 '' N, 22 degrees 53'00 '' E) (15 m in height) of this palaeobasin is composed of two sediment complexes of different genesis and age. The lower part consists of silt and very fine-grained sand of lacustrine origin. According to palynological data, the lacustrine sediments accumulated under boreo-arctic climatic conditions. The pollen records suggest that local vegetation was sparse forest with open areas. An Optically Stimulated Luminescence (OSL) date of the lacustrine sand yielded an age of >79 +/- 6 ka, which indicates that lacustrine conditions may have occurred during part of the Early Weichselian Odderade Interstadial (Jonionys 2). However, the palynological data from Svirkanciai suggest a Middle Weichselian age, possibly correlating with the Oerel Interstadial (Jonionys 3) 55 ka ago. No traces of early Middle Weichselian Schalkholz (Nemunas 2a) stadial glacial advance have been found in the Venta sections. This also suggests a Middle Weichselian age for the Svirkanciai lacustrine sediments.