Problemy litologii i sedymentacji dolnego karbonu w Polsce

Abstract

LITHOLOGICAL AND SEDIMENTARY PROBLEMS OF THE LOWER CARBONIFEROUS IN POLANDIn the paper the Tournaisian and the Upper Visean deposits are discussed on the basis of their exposures found in the Święty Krzyż Mts., in the marginal area of the Upper Silesian Basin, in East-Sudetes, and on drill materials.When discussing the lithological problems the author uses a subdivision into several various units. The subdivision is based not only upon the lithological development of the deposits, but also on their tectonic conditions which have existed at the time of origin. Here, the following fades have been distinguished: Culm fades, argillaceous-siliceous fades, Carbonaceous limestone facies and chemical facies. The Culm, developed as arenaceous greywacke deposits, is characteristic of great thickness. This is connected with the geosynclinal areas. The argillaceous-siliceous facies is represented by argillaceous deposits of small thickness, with intercalations of siliceous and greywacke schists. The Carbonaceous limestone facies comprises various deposits containing intercalations of organogenic limestones. Thicknesses of these series are small, too. The chemical facies comprises deposits of chemical origin, i.e. dolomites and anhydrites. The three latter fades are related to the stable areas.In the Tournaisian there are found all the facies discussed above. The Culm facies is connected with the northern and eastern margin of West-Sudetes. lts branch extends as far as the Łysogóra region of the Święty Krzyż Mts. North of this facies, the Tournaisian deposits are not encountered. South of the Culm facies there runs a belt of argillaceous-siliceous sedimentation. In the south, round about the pre-Carpathian massif a sedimentary zone of the Carbonaceous limestone is developed. The areas of eastern and northeastern Poland are lacking deposits of Tournaisian age. They occur only within an isolated sheet in the area of the upper Bug river. In the author's opinion, there existed here some communication ways of this basin with the open seas, in the south. The extents shown on the map reflect the present-day conditions.At the Upper Visean time, there begun significant changes and simultaneously an enlargement of the sedimentary basin took place. Distribution of facies in southwestern Poland is similar to that which has existed at the Tournaisian time. In this period of time there appeared a widening of the areas previously occupied by the Upper Visean deposits. The replacement of the Carbonaceous limestone facies by the argillaceous-siliceous fades in the top beds of the Cracow region seems to be very important here. The areas stretching in the region of Cracow and lacking Visean deposits partly were alimentation zone of these latter. Within the Lublin Coal Basin, in the Tournaisian denudation area, the deposits of paralic type have sedimented. Except for the bottom deposits of the Lower Visean, the ·calcareous deposits predominate in the cyclically arranged series. The Lublin cyclothems are reduced to two beds lower bed of marine limesltones, and upper bed of continental stigmaria strata, with thin interbeddings of coal. According to the Wanless's and Shepard's subdivision, they correspond with the neritic and partly with the deltaic formations, as well. In the area of northern Poland, the ,Upper Visean is developed as Carboniferous limestones (argillaceous-coaly deposits), secondarily dolomitized. That has been recognized by one bore hole only (Bobolice).Throughout the entire area of Poland are found mainly platform-type deposits developed on the stiffened Caledonian basement. The Variscian geosyncline is of restricted extension an is connected with the marginal area of West-Sudetes, the branch of ,which constitutes the Łysogóry region. Thus, at the Dinantian time, a basin has developed in Poland between the East-European platform and the Caledonides of West-Sudetes and pre-Carpathians.