Obecny podział litostratygraficzny czerwonego spągowca w Polsce i propozycje jego sformalizowania

Abstract

Przedstawiono dotychczasowe schematy stratygraficzne czerwonego spągowca w Polsce oraz zaproponowano podział na formalne jednostki litostratygraficzne. Podstawą ich wydzielania powinny być wyłącznie cechy litologiczne, a nie kryteria sedymentacyjno-diastroficzne. Pozwala to na maksymalne uproszczenie podziału.THE CURRENT LITHOSTRATIGRAPHIC SUBDIVISION OF THE ROTLIEGENDES IN POLAND AND PROPOSITION OF ITS FORMALIZATIONGeological-prospecting works, carried out in the last twenty. years in Poland, markedly contributed to the knowledge of the Rotliegendes beyond the areas of its outcrops in the Intra- and North-Sudetic depressions and Silesian-Cracow region. Table 1 presents the hitherto used stratigraphic subdivision of the Lower Permian. In that subdivision, the Rotliegendes is divided on the besis of changes in lithology only and its Iithostratigraphy - on analysis of cyclicity in sedimentation (Table 1). In the compilation, there are also presented results of floral and palynological studies concerning stratigraphic position of the Karniowice sinter and Anthracosia shales.The major difficulties encountered in establishing Iithostratigraphic units in·the Rotliegendes are those related to interpretation of well logs. Lower Permian rocks are primarily characterized by irregular and discontinuous distribution. These disadvantageous features make it necessary to find boundaries enabling unequivocai determination of the range of previously defined units even on the basis of scarce core material.A sedimentary series separating Carboniferous or older bedrock and volcanic rocks is here interpreted as the oldest formation (Table 2). That formation is as a rule overlain by volcanic rocks, often intercalated with the sedimentary ones. The first and last appearances of volcanic rocks should be accepted as boundaries of the volcanic formation (Table 2).Conglomerates; interpreted as basal conglomerates of the Upper Rotliegendes, were traced in relatively large area. The author proposes to differentiate them as a separate formation (Table 2).A complex of sandstones or siltstones, separating the basal conglomerates of the Upper Rotliegendes  and the Copper-bearing Shale or Basal Limestone of the Zechstein is the youngest formation here (Table 2).In marginal pints of the Lower Permian basin, the premises for subdivision of the Upper Rotliegendes into two formations are missing and the author proposes to differentiate one formation only. That solution, resulting from the replacement of the two formations from central part of the basin by a single one in marginal zones (Table 2), well reflects differentiation in sedimentary·environments of the Upper Rotliegendes. The differentiation may be explained by either the activity of the Mid-PoIish·aulacogen, the formation of which has begun at that time, or local tectonic conditions.