Stratygrafia utworów cechsztyńskich zachodniej części niecki północnosudeckiej

Abstract

STRATIGRAPHY OF THE ZECHSTEIN SEDIMENTS IN THE WESTERN PART OF THE NORTH SUDETIC TROUGHSummaryRecently new drilling data were obtained from the Zechstein sediments in the western part of the North Sudetic trough (Fig. 1) and the stratigraphy and paleogeography of the area discussed were reinterpreted accordingly (Figs. 2–4; Tabl. 1). In the first instance it has been found that the sulphate series with red-brown claystones intercalations overlying the Z1 cyclothem (Werra) carbonate represents the anhydrite horizon of the same cyclothem and not the Z2 cyclothem (Stassfurt) as previously assumed (O. Eisentraut, 1939; G. Richter-Bernburg, 1950; J. Krasoń, 1962, 1964; J. Milewicz, 1973a, b).Consequently the Z2 cyclothem (Stassfurt) sediments are completely lacking in the south-eastern portion of the area. They appear slightly farther to the north-west and contain the main dolomite (Ca2), the basal anhydrite (A2) and, locally, the older rock salt (N a2) horizons.On the other hand the Z3 cyclothem (Leine) sediments commonly accompanying Z1 cyclothem (Werra) sediments are lacking in several boreholes of the north western and northern part of the area. Completely missing are the Z4 cyclothem (Aller) sediments. The red-brown massive claystones and siltstones with anhydrite inclusions (Fig. 5), so far regarded as equivalents of this cyclothem, can be readily correlated with the almost identical sediments from other parts of the Fore-Sudetic zone (M. Podemski, 1973) transgressively overlying the sediments of all four Zechstein cyclothems.In the palaeogeographic picture zones of shallower and deeper facies stretched the NNW–SSE direction are marked (Fig. 6), complying with the distribution of various facies in the western part of the Fore-Sudetic zone.