Osady czwartorzędowe w wykopie kopalni węgla brunatnego Bełchatów

Abstract

Komunikat wstępnyW kopalni węgla brunatnego koło Bełchatowa, w wyniku zdejmowania nadkładu, odsłonięte zostały osady czwartorzędowe o miąższości 30 m. Profil nawiązano do opracowania szerszego regionu, opartego na pracach geologiczno-zdjęciowych i analizie profili wierceń. W odsłonięciu leżą od góry: osady holoceńskie, osady rzeczne należące do zlodowacenia bałtyckiego oraz osady zlodowacenia środkowopolskiego (gliny zwałowe, osady wodnolodowcowe i zastoiskowe). Stwierdzono też osady jeziorne, dotychczas w tym profilu nie znane. Podjęto badania laboratoryjne osadów jeziornych i glin zwałowych dla wyjaśnienia stosunków stratygraficznych facjalnych. Odsłonięcie w kopalni należy do najlepszych odsłonięć osadów czwartorzędowych w Polsce i dostarcza materiałów o znaczeniu praktycznym i naukowym. QUATERNARY DEPOSITS FROM EXCAVATION OF BEŁACHATÓW OPEN-COAST MINEPreliminary noteRemoval of blanket deposits the brown-coal open-cast mine from the vicinities of Bełchatów started in 1977 and the excavation was about 30 m deep in October, 1977. At that time the profile of western wall of the excavation was at follows (from the top downwards; see Fig. 1): Holocene peats, sands and silts; the wall is situated in the area of ancient floodplain of Widawka river;Pleistocene fluvial sands and some sands with gravel admixture, deposited by the Widawka river and mainly belonging to the Baltic Glaciation;Tills of the Mid-Polish Glaciation, wedging out in the proximity of shores of buried lake (see below); there were found differences in distribution, appearance and composition of tills from two sections of the exposure which rises a question whether we are dealing here with one or two separate stages; the comparison with results of detailed geological mapping of the neighbouring areas showed that the till from southern part of the exposure belongs to the Warta stage;Lacustrinal deposits (silts, gyttja, silts gyttja, peats and sands) occurring in central part of the studied section of the exposure; their presence was not revealed by previously made boreholes (of so called line 92) and their relation to tills in unclear;Fluvioglacial sands and ice-dammed lake sands and silts the bulk of which originated during transgression of the icesheet of the Warta stage and only some could have originated earlier;Ice-dammed lake varved clays forming almost continuous layer throughout the exposure and underlain by humus silts of unknown age in some places; the stratigraphic position of these clays should be reanalysed.The exposure made it also possible to analyse sedimentary structures and deformations of layers. In order to elucidate stratigraphic relations and fades problems there were initiated further field studies, palynological and petrographic laboratory studies and geological consultations.The exposures from the “Bełchatów” mine are nowadays the best exposures of the Quaternary deposits in the Polish Lowlands. The analysis of this profile is also highly important for selecting optimum method of removal of blanket deposits and estimating stability of escarpments and terraces in the area of this mine.