O wpływie rzeźby podłoża na powstawanie niektórych złóż węgla brunatnego oraz na ich warunki hydrogeologiczne inżyniersko-geologiczne
Abstract
INFLUENCE OF RELIEF UPON FORMATION OF CERTAIN BROWN COAL DEPOSITS AND UPON THEIR HYDROGEOLOGICAL AND ENGINEERING-GEOLOGICAL CONDITIONS
Summary
Within the Łódź trough (Central Poland) the Mesozoic formations characterized by diversified top surface (Fig. 1) underlie the Quaternary and Tertiary deposits. In the vicinities of Konin, Koło and Turek, situated within the Warta River basin, the substratum is built up of Upper Cretaceous marls. Drilling results have demonstrated that in these areas Tertiary erosional valleys occur in the top parts of these marls. Flat bottoms of these valleys are more than 1 km in width. In the marginal zones of the valleys elevated rock complexes are found to occur frequently a few metres below earth surface only. The valley bottoms are incised into the Upper Cretaceous marls to a depth of about 80 m. Along the buried valleys a number of higher erosional horizons occur. The bottoms of main valleys are connected with those of small valleys and erosional incisions that form a very dense net of smaller tributaries (Figs 1 and 2). It has proved that the occurrence of brown coal deposits is connected with these buried valleys and with their lateral tributaries. The author makes a comparison of the occurrence conditions of a deposit „A" (vicinities of Turek) with those of a deposit „B" (vicinities of Konin). In both regions the geological conditions are similar (Fig. 3). The connection of brown coal deposits with buried valleys exerts a considerable influence upon their hydrogeological and geotechnical conditions. It has been demonstrated that at the margins of the buried valleys an isolating layer built up of clay silts and weathered marls occurs between the Upper Cretaceous marls and the sub-coal water-bearing sands, whereas the bottom areas of the valleys lack any isolating layer. This is of considerable importance for exploitation of deposits since in this case the fissured water-bearing marls must be drained off together with the sub-coal water-bearing sands.
Summary
Within the Łódź trough (Central Poland) the Mesozoic formations characterized by diversified top surface (Fig. 1) underlie the Quaternary and Tertiary deposits. In the vicinities of Konin, Koło and Turek, situated within the Warta River basin, the substratum is built up of Upper Cretaceous marls. Drilling results have demonstrated that in these areas Tertiary erosional valleys occur in the top parts of these marls. Flat bottoms of these valleys are more than 1 km in width. In the marginal zones of the valleys elevated rock complexes are found to occur frequently a few metres below earth surface only. The valley bottoms are incised into the Upper Cretaceous marls to a depth of about 80 m. Along the buried valleys a number of higher erosional horizons occur. The bottoms of main valleys are connected with those of small valleys and erosional incisions that form a very dense net of smaller tributaries (Figs 1 and 2). It has proved that the occurrence of brown coal deposits is connected with these buried valleys and with their lateral tributaries. The author makes a comparison of the occurrence conditions of a deposit „A" (vicinities of Turek) with those of a deposit „B" (vicinities of Konin). In both regions the geological conditions are similar (Fig. 3). The connection of brown coal deposits with buried valleys exerts a considerable influence upon their hydrogeological and geotechnical conditions. It has been demonstrated that at the margins of the buried valleys an isolating layer built up of clay silts and weathered marls occurs between the Upper Cretaceous marls and the sub-coal water-bearing sands, whereas the bottom areas of the valleys lack any isolating layer. This is of considerable importance for exploitation of deposits since in this case the fissured water-bearing marls must be drained off together with the sub-coal water-bearing sands.