Warunki geologiczno-górnicze w Lubelskim Zagłębiu Węglowym

Abstract

GEOLOGICAL AND MINING CONDITIONS IN THE LUBLIN COAL BASINSummaryAs a result of the systematic geological-prospecting works carried out in the eastern part of the Lublin province a new, large coal basin has been discovered, called now the Lublin Coal Basin. Its natural boundaries are found in that area from the north-eastern part only (outcrops of productive series under the Mesozoic formations). From the east, the State boundary is here its eastern boundary and the basin itself passes into the Lwow-Volhynia one. In the south-west the boundary has been drawn tentatively, according to the contour line that corresponds to the thickness of overburden equal to 750 m (Figs 1 and 2). Thus, the basin is only part of a larger Carboniferous trough that stretches in a western or north-western direction.The Carboniferous formations of the Lublin Coal Basin rest discordantly on the older ones. Stratigraphically, they are represented by sediments that correspond to the Carboniferous section from the Upper Visean up to the Westphalian B inclusive (Figs 3 and 4). The Visean formations are developed mainly as marine deposits (limestones, marls, clays) with single intercalations of lagoonal and continental sediments (stigmarian soils, thin coal interlayers). The deposits of the Lower Namurian (A) are developed as paralic series with marine influences decreasing upwards. For the most part, these are clay sediments with numerous limestone and thin coal interbeddings. The deposits of the Upper Namurian (B-C) and of the Westphalian A are characterized by the high percentage of sandstones, by single limestone intercalations, and by numerous coal interbeddings (locally 0,8–1,2 m in thickness). In the Lublin Coal Basin the uppermost series of the Carboniferous formations are mainly built up of siltstone-claystone deposits that reveal rich coal intercalations and seams, Westphalian B in age (Fig. 4). In a later period these deposits underwent erosion, and now are preserved with different thicknesses.Above the top part of the Carboniferous deposits there are found Jurassic, Cretaceous and Quaternary formations, all approximately .from 500 to 750 m in thickness.The Carboniferous formations of the Lublin Coal Basin stretch from NW to SE and dip under a small angle (up to 3°) south-westwards. The deposits of Westphalian B age are the main productive member here. They reveal about 20 payable coal seams, from 0,8 to 4,1 m in thickness. Among them 4 seams are remarkably stable ones, 4 are less stable, but practically very important, 5 being unstable. Locally, however, they can easily be worked out. The total thickness of the payable seams found in the area most promising for coal mining ranges from 10 to 20 m.The coal seams distinguish themselves in having the mean ash content equal to 9,1–19,1%, total sulphur content ­ 0,77–2,75%, and heating value – 5851– 6810 cal/g.As far as the overburden above the Carboniferous formations is concerned, the most important for mining activity are here the Jurassic formations and the overlying Albian deposits. These formations, mainly carbonate ones, are characterized by the increased water saturation degree and water pressure that reaches here up to several dozen atm. The Upper Cretaceous carbonate deposits (marls, marly limestones, chalk) found to occur on the Albian arenaceous deposits, or at places immediately on the Jurassic limestones, will not produce any technical problems to coal mining of the future, except for the uppermost member (down to a depth of 80–120 m), where they are cracked and weathered. Their connection with the Quaternary deposits make here one upper water-bearing horizon.This area, most promising in the Lublin Coal Basin for coal mining industry, has been subdivided by mine designers into three regions: northern, central and southern. The northern and the central regions do not reveal any free methane emission. Only beneath the depth of 850–900 m a small methane accumulation has been observed to occur, adsorbed in the coal seams.The geologic-depositional conditions of the Lublin Coal Basin are no doubt much less favourable than those of the richest coal-bearing areas of the Upper Silesia particularly than those of the areas in which the deposits of the Saddle Beds and of the Lower-Ruda Beds reach a depth of 1000 m. Nevertheless, for the Upper Silesian areas, where the deposits of siltstones series (Orzesze Beds) and of the paralic series (Marginal Beds) occur, the utmost coal-bearing areas of the Lublin Coal Basin represent an equivalent alternative or even a competition.