Nowe profile wiertnicze utworów karbonu produktywnego w południowo-wschodniej części Górnośląskiego Zagłębia Węglowego

Konrad Konior, Elżbieta Turnau


New coal measure sections from boreholes of the south-eastern part of the Upper Silesian Basin

Geologic setting. — The limits of the Upper Silesian Basin are marked by outcrops of coal measures except for the southern one which is obscured by the Carpathian overthrust. The boreholes Tomice 1, Piotrowice 1, Spytkowice 200 and Zagacie 1 (Fig. 1), which have penetrated the Carpathian flysch and/or thick Miocene cover, furnish new information on the development and range of the south-eastern part of the Basin.
General stratigraphy. — The stratigraphical subdivision and correlation of the coal measures is presented in Figs. 2 and 3. This is based upon palynological studies, electric and radiometric logging and, in the case of the Zagacie 1 borehole, only on lithology and interpretation of geophysical data. The depths of occurrence and thicknesses of the particular lithostratigraphic units are shown in Table 3. It appears that in this part of the Upper Silesian Basin the coal measures are represented by deposits of the „Synclinal group” (Westphalian), and the „Marginal group” (Namurian A) while those of the „Anticlinal group” (Namurian B/C) are missing. The occurrences of more important spore genera and species in samples from Tomice 1, Piotrowice 1 and Spytkowice 200 boreholes are shown in Table 1. Four spore assemblages are recognized, which are as follows: The first assemblage is characteristic of the Libiąż „Beds” (= Formation), Westphalian D, and occurs in the Spytkowice 200 and Tomice 1 boreholes. The diagnostic species of this assemblage are: Foveolatisporites fenestratus (Kos anke and Brokaw) Bhardwaj, Punctatosporites minutus Ibr ahim, Punctatosporites granifer Potonié and Kremp, Verrucososporites obscurus (Kosanke) Potonié and Kremp, and Torispora securis Вalme. The relatively high frequency of Densosporites and Torispora suggests that these beds represent the lower part of the Libiąż „Beds”, lower Westphalian D. The second assemblage, characteristic of the lower part of the Łaziska „Beds” s.l. (lower Westphalian C) or upper part of the Orzesze „Beds” s. 1. (upper Westphalian B) was found in all three boreholes. The diagnostic species of this assemblage are Microreticulatisporites nobïlis (Wiсher) Knox, Punctatosporites minutus Ibrahim, Florinites triletus Kosanke, F. volans Potonié and Kremp, F. junior Potonié and Kremp, Cristatisporites indignabundus (Loose) Potonié and Kremp, Endosporites ornatus Wilson and Coe, Endosporites zonalis (Loose) Knox, Vestispora costata (Balme) Bhardwaj , V. tortuosa (Balme) Bhardwaj. The third assemblage, characteristic of middle and lower part of the Orzesze „Beds” s. 1. and of upper part of the Ruda „Beds” s. 1. (Westphalian A/В), was found in all three boreholes. The diagnostic species of this assemblage are Cyclogranisporites leopoldi (Kremp) Potonié and Kremp, Raistrickia pallida Dybоva and Jachowicz, R. saetosa (Loose) Schopf , Willson and Bentall, Pustulatisporites pustulatus Potonié and Kremp, Dictyotriletes reticulocingulum (Loose) Smith and Butterworth, Reinschospora speciosa (Loose) Schopf , Willson and Bentall, Novisporites irregularis (Kosanke) Bhardwaj, Alatisporites pustulatus Ibr ahim, Bellispores bellus Artüz and Schulzospora sp. Spores belonging to Radiizonates and Cingulizonates are common in this assemblage. The fourth assemblage, characteristic of the Marginal „Beds” (Namurian A), was found in all three boreholes. The diagnostic species of this assemblage are Rotaspora fracta (Schemel ) Smith and Butterworth, Tripartites pseudoianthiana Jachoicz, T. rugosus (Horst ) Dybоva and Jachowicz, T. cristatus Dybоva and Jachowicz, T. trifoliatus Dybоva and Jachowicz, Chaetosphaerites pollenisimilis (Horst ) Butterworth and Williams, Bellispores nitidus (Horst ) Sullivan. In the Spytkowice 200 and Tomice 1 boreholes only the lower part of deposits of the Namurian A age was discovered and is indicated by the occurrence of the following forms: Triquitrites trivalvis (Waltz) Potonié and Kremp, Diatomozonotriletes spp., Tetraporina sp. and Lagenicula splendida (Zerndt ) Potonié and Kremp. In the Tomice 1 borehole a mixed Westphalian-Namurian spore assemblage was also found (for spore forms and sampled levels see Table 2), which indicates redeposition of Namurian spores during the Westphalian. There are lateral differences in lithology of the coal measures in the particular boreholes. These are most distinct within the Westphalian strata in the boreholes Tomice 1 and Piotrowice 1; in the Tomice 1 borehole down to the bottom of the upper part of the Orzesze „Beds” s. 1. (upper Westphalian B) there is a marked preponderance of sandstones while in the Piotrowice 1 borehole argillaceous rocks predominate. In the Piotrowice 1 borehole intercalations of clayay siderites were found in the Westphalian and Namurian A strata; also amount of coal seams in this borehole is greater than elsewhere. This suggests that in the Piotrowice area there were conditions favourable for greater accumulation of plant substance and for creating coal seams and also the clayay siderites. The deposits of the „Marginal Group” (the Namurian A) are developed as sandstone-siltstone series in the Spytkowice — Zagacie region and shale-siltstone series in the Piotrowice — Tomice area. So the lithologie character of rocks in the SE part of the Upper Silesian Basin is variable with local singularities. The above study and also the data concerning some older boreholes drilled in the discussed area enabled the first author to draw a new probable south-eastern limit for the Upper Silesian Basin (Fig. 5, see also Konior 1971) and to present a general geological section through the southern part of the basin (Fig. 4).

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