Przekrój geologiczny przez osady permsko-mezozoiczne Niecki Nidziańskiej

Abstract

GEOLOGICAL CROSS SECTION THROUGH THE PERMO-MESOZOIC DEPOSITS OF THE NIDA TROUGH

Summary

The deep geological structure of the Nida trough, which is an important structural element of South Poland (Fig. 1), has not so far been examined in detail. Based on the results obtained from three deep drillings (Węgleszyn, Jaronowice and Węgrzynów) the authors present the first geological cross section made through the Permo-Mesozoic deposits found to occur in the central part of this structure (Fig. 2).
The Permo-Mesozoic formations comprise a series of beds from Zechstein to Maastrichtian inclusive. Certain stratigraphical members may, however, be absent at several places pierced by the bore holes, or along the entire cross section under examination (Figs. 2 and 3).
The tectonics of this area is of multistage nature. In the the Permo-Mesozoic substratum of the Nida trough there are found Caledonian structures (K. Jaworowski, H. Jurkiewicz, Z. Kowalczewski, 1967) and Variscan structural elements superposed on them in the south-westerly part at the area in study (J. Znosko, 1965). The strongly disturbed strata of the older substratum are in an immediate contact with various, always discordant beds of Permian and Jurassic age.
The Nida trough, a wide syn-Alpine structural element, was gradually formed in a period from Permian to Palaeogene inclusive. Several sedimentary-diastrophic sub-cycles, superposed on each other, may be distinguished within the Permo-Mesozoic structural stage as follows: Zechstein (?) sub-cycle, Triassic (Old-Cimmerian) sub-cycle, Rhaetic (?) sub-cycle, Jurassic (Young-Cimmerian) sub-cycle, and Cretaceous sub-cycle. The strongest tectonical disturbances, related to thesesub-cycles, took place still before the Dogger and the Miocene, whose transgression invaded the area of an already mature depression-like element from the south.