GENEZA MISY JEZIORNEJ I WARUNKI ŚRODOWISKOWE AKUMULACJI LIMNICZNO-BAGIENNEJ W INTERGLACJALE MAZOWIECKIM W ROWIE KLESZCZOWA (ŚRODKOWA POLSKA)

Abstract

THE ORIGIN OF A LAKE BASIN AND ENVIRONMENTAL CONDITIONS OF LACUSTRINE-BOGGY DEPOSITION IN THE KLESZCZÓW GRABEN (CENTRAL POLAND) DURING THE MAZOVIAN INTERGLACIALAbstract. In the long sequence of Pleistocene events recorded in the Kleszczów Graben deposits, lacustrine sediments of the Mazovian Interglacial constitute an important member. Mazovian deposits were encountered in the Folwark 93K site. In the Folwark area, lacustrine sediments occurred in a syncline formed by an ice-sheet in a basal moraine till. The till was overlain by a sand layer deposited during a deglaciation period. Later, lacustrine accumulation was initiated at the beginning of the interglacial. The sequence of events recorded in the deposits indicates that the area of Central Poland already was glaciated before the Mazovian Interglacial. This conclusion contradicts the opinion that the warm period was separated from the previous interglacial by a cool period with an exclusively periglacial environment. Organic deposits, infilling the depression at the Folwark 93K site, were investigated by a pollen and diatom analysis. The results of the both the analyses indicate that accumulation of these deposits took place during the Mazovian Interglacial. According to changes in diatom composition and relative diatom frequency (percentage contribution of diatoms), seven local diatom assemblage zones were distinguished. These zones represent the diatom succession being the basis for characterisation of four main evolutionary phases of the ancient lake at Folwark, supported by the results of palynological investigations. The evolutionary phases of the Folwark lake were compared with development phases of the Adamówka lake (Sandomierz Basin), which is of the same age. The study also proved similarities in the development of these lakes to the lakes of the Likhvinian Interglacial in Russia and Alexandrian Interglacial in Belarus.