Zarys stratygrafii kredy dolnej w niecce mogileńskiej

Abstract

OUTLINE OF THE LOWER CRETACEOUS STRATIGRAPHY IN THE MOGILNO TROUGHSummaryAs compared with the Lower Cretaceous basin, the centre of which is situated in the Kujawy region of the Danish-Polish sedimentary furrow, the Mogilno trough, which is part of this central sedimentary zone seems to be of particular significance. The north-western part of the trough leans to the central Kujawy sedimentary zone. The thickness of the Lower Cretaceous deposits, at places from 500 to 600 m, is not lesser than that in the other areas of the Kujawy region. The section is represented by a complete series of deposits, from Berriasian to Middle Albian. The south-western part of the trough, covering an area of Trzemżal, Janowiec, Rogoźnoand the southern portion of the Szamotuły anticline, belongs to the peripheral zone of the Lower Cretaceous basin, and is characterized by a reduction in stratigraphical section, mainly as concerns Berriesian and Valanginian, more to the south-east –  partly Hauterivian as well. As far as Berriasian is concerned, ammonite fauna proves the Riasanites horizon (Riasanites cf. rasanensis (N e n e t z k y) L a h., Berriasella sp., Berriasella cf. jauberti (M a z e n o t.) and the Surites horizon (Surites cf. subtzikwinianus ?, Neocosmoceras sp. and Euthymiceras sp.), and in the Valanginian – the Platylenticeras horizon (fragments of Platylenticeras sp.). Other members of the Valanginian, and Lower Hauterivian (Lyticoceras horizon) are distinguished on microfauna and on comparisons with the deposits evidenced by ammonites in the neighboring Kujawy region.The deposits of Upper Hauterivian – Middle Albian age are faunistically not evidenced. Facial arrangement that shows the highest sand content in the deposits laid down within the north-eastern part of the trough (Gopło area) proves here a considerable importance of the alimentation area of both the East-European platform and the Świętokrzyskie Mountains.