LOESS GRAIN-SIZE AND MAGNETIC SUSCEPTIBILITY AS A PROXY RECORD OF CLIMATIC CHANGES DURING OIS2 IN POLAND AND WEST UKRAINE

Polish loess areas are situated in the central part of the European loess belt and, because of its geographical position, they belong to the most interesting in Europe. Loess in the Eastern part of the country has relatively big thickness (max. 40 m) and is similar to the Ukrainian loess. Loess patches in SW Poland are thinner (3-5 m, max. 15 m) and sediment properties are much the same as of the western European loess. The development of loess covers in Poland reflects therefore present and Pleistocene climatic conditions; continental in the east and more oceanic in the west. As a result of extensive field research, ten of the most complete last glacial loess sequences from Poland and West Ukraine were chosen for detailed investigation. All profiles were sampled at close intervals (5 or 10 cm) and documented in respect to their stratigraphy, sedimentology and palaeopedology. The grain-size distribution, determined by laser diffraction, magnetic susceptibility, CaCO3 and organic carbon content were measured in order to recover records of changing climatic conditions during OIS 2. The results indicate the occurrence of short-term depositional cycles within the thick loess sequences; relatively coarse loess is alternated with fine-grained loess. Periods of high dust influx coincide with severe climate conditions, as inferred from grain-size variations. Periods of decreased accumulation of fine-grain loess and development of weak pedogenic gley horizons, marked by relatively low values of magnetic susceptibility, represent warmer episodes. Short-duration climatic cycles recorded in Upper Weichselian loess sequences from Poland and West Ukraine can be correlated with the Dansgaard-Oeschger events in ice-core records. This implies that the influence of Dansgaard-Oeschger events during the Last Glaciation was not confined to Greenland but extended as far as central/eastern Europe borderzone.