Kajper czy pstry piaskowiec? Problemy litostratygrafiitriasu kujawskiego odcinka wału środkowopolskiego - dyskusja

Abstract

KEUPER OR BUNTSANDSTEIN? PROBLEMS OF THE TRIASSIC LITHOSTRATIGRAPHY IN THE KUJAWY SEGMENT OF MID-POLISH SWELL - DISCUSSION Summary Liszkowski and Topulos (Prz. Geol., 44, 1996) attempted to correct the Triassic lithostratigraphy in two boreholes (Krośniewice IG 1 and Rdutów 2) located in the central part of the Mid-Polish Trough. They significantly changed the position of the Muschelkalk series which resulted in the thickness reduction of the Keuper series to about 300 m while its thickness accepted so far reached even 2000 m. These changes were exclusively based on the analysis of well logs. However, the authors neglected the occurrence of characteristic fossils (among others fragments of Ceratites) in a part of the Krośniewice sequence claimed by them to belong to the Bunter series, as well as the presence of rock salts in a part which was included by them into the Lower Muschekalk. In fact, the former represents the Muschelkalk and the latter - the Keuper. Rock salts in the so-called Lower Gypsiferous Series were encountered in many boreholes in central Poland. Moreover, the authors incorrectly interpreted the results of reflection seismic data: their supposed Muschelkalk reflectors are in fact intra-Keuper ones and alleged Zechstein horizons represent the Muschelkalk (Fig. 1). Therefore we think - using the Authors' own words – that not the previous researchers but the Authors themselves made " ... grave errors ... " and that the discussed parts of both sequences do belong to the Keuper series as they did earlier. Their great thickness points to the initial mobilization of the Zechstein salts which were squeezed out from below the Krośniewice Syncline.