Ripplemarki w utworach pstrego piaskowca monokliny przedsudeckiej w rejonie Lubina

Abstract

RIPPLE MARKS IN THE BUNTSANDSTEIN FORMATIONS OF THE FORE-SUDETIC MONOCLINE, LUBIN REGIONThe article presents some remarks and observations on the lithology and sedimentation of the  Buntsandstein formations of the Fore-Sudetic monocline in the region of Lubin. The deposits occurring in this area are developed as pink, fine-grained quartz sandstones with thin intercalation of cherry and green clay shales. Lithological character of the Buntsandstein deposits reveals a repeated  irregular  rhythmicity, and appears in the form of alternating thin-layered and thick-bedded sandstones; it can also be observed as clay shale intercalation and parallel diagonal, rarely also cross stratification of deposits. Horizontal extent of these phenomena is strongly differentiated. Lamination can be traced uninterruptedly along some scores of centimeters, and intercalation of clay shales are found along a distance of several metres. On the other hand, the complexes of thin-bedded and coarse- bedded sandstones may be correlated in an area of some scores of metres.Frequently, the Buntsandstein formations disclose here a series of irregularities occurring on bedding planes. In most cases these are ripple marks, the morphology of which, and the intrinsic structure, distinctly point to its aqueous environment origin.They are represented by two fundamental types, i.e. wave ripple marks and interference ripple marks. As far as their shape, size and preservation degree are concerned, they are characterized by a considerable variety. In vertical section, the ripple marks are concentrated in the middle part Buntsandstein, mainly in the thin-bedded portions that contain numerous clay shale intercalation. In cross section, in turn, the wave ripple marks are characterized by diagonal bedding, a complete lack of lamination is, however, rarely observed. An increasing form represented by oval hollows has most probably been formed as a result of impression of clay balls in loose sediment. Moreover, the  Buntsandstein formations reveal some traces of desiccation that occur in the form of polygons or nodulous swells being the result of repeated soaking and drying-up of clay. In addition, there are also observed various hieroglyphs, the origin of which is here completely enigmatic. The character of Buntsandstein bank surfaces is highly interesting mainly due to a great diversity of the forms mentioned above, and owing to their importance for detailed determination of sedimentary conditions. Ripple marks and desiccation traces, as well as lithological features of deposits, such as diagonal bedding and frequently found wedging out of strata, are here typical phenomena of Buntsandstein, similarly as they are in the other areas of Poland.