GEOHISTORY OF AN UPPER WEICHSELIAN OXBOW LAKE FROM HUNGARY (CENTRAL EUROPE)

One of the largest late Pleistocene paleochannels is situated in the SW part of Hungary, at Kardoskút village, on the area of the Körös – Maros National Park. This oxbow lake was nominated Fehér-lake (White-lake) because the highly alkaline lacustrine water is strongly connected to the fluctuating water table so the lake quite often dries completely out during the hot and dry summers leaving behind a white amorphous silicate dust cover on the dried lacustrine bottom. The natural floodplain vegetation is soloncak steppe (Artemisio – Festucetum pseudovinae) with loessic steppe around the lake where the surface sediments consist of infusion (alluvial) loess to a depth of 2-3 ms underlain by fluvial sands. Inwards the prevailing marsh vegetation is dominated by Carex – Typha latifolia – Phragmitetum australis stands. The Fehér-lake is situated on the alluvial fan of the Körös and Maros rivers. The lake was formed by avulsion, a whole channel segment was abandoned, and the river adopted a new course, probably after a severe flood. The length of the lake is 4 km long in the E – W direction and the width of the lake is 100 – 500 m N – S direction. This paper presents the first results of a multidisciplinary paleoecological study aimed at reconstructing the late Quaternary environmental and paleohidrological history of the Fehér-lake. The gained results of the applied complex methods of sedimentology, pollen, mollusk, and geochemical analyses controlled with radiocarbon dating revealed a sedimentary sequence extending back into the last glacial.