Osady piaskowcowo-zlepieńcowe triasu dolnego w południowo-wschodniej części obszaru przedsudeckiego

Zbigniew Deczkowski, Irena Gajewska

Abstract


THE LOWER TRIASSIC SANDSTONE-CONGLOMERATE DEPOSITS IN THE SOUTH-EASTERN PART OF THE FORE-SUDETIC AREA

Summary

The article deals with the problem of the age of the sandstone-conglomerate complexes found to occur immediately on the basement older than the Permian, and overlain with Roethian or the Middle Buntsandstein deposits, frequently referred to the Rotliegendes. In the southern part of the area a distinctly marked morphological ridge of Lubliniec can be observed in the palaeomorphology of the Buntsandstein substratum (Fig. 1). The rocks of the Lower Carboniferous, the Devonian and the older Palaeozoic, which build up the area in study, had been, after the Permian period, intensely denuded. At foothills, at reworked rocks formed during the Lower Triassic time the conglomerate-sandstone deposits. At places, under the Triassic and on the Permian substratum a bed of brown claystones occurs representing  probably the Zechstein formations (Fig. 2).
The sandstone-conglomerate complex of the Lower Buntsandstein resembles in its petrographical composition the Rotliegendes deposits; it has also been encountered in bore holes Rzeki IG 1, Ślęzany L-1, and Biała Wielka IG 1 (Figs. 1 and 3). The detailed analysis of the drilling sections and a comparison of these sections with those characterized by a better development, where the Zechstein deposits are preserved, lead to a conclusion that deposits under consideration were laid down at the Buntsandstein period.
Both the lithological nature and the petrographical composition of the conglomerates cannot represent a basis for the determination of their age. As the best examples serve here the sections of the bore holes made in the vicinity of Laskowice Oławskie, where conglomerates of Rotliegendes and Buntsandstein age occur, characterized by similar petrographic composition. These two conglomerate complexes of different age are separated with the sulphate-carbonate deposits of the Zechstein.


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