Paleogene marginal marine sedimentation in central-western Poland

Abstract

The Paleogene deposits of central-western Poland area have been studied in more than 300 boreholes and several outcrops with lithological, mineralogical and sedimentological methods. Grain-size analyses, heavy mineral analyses, XRD analyses and pebble analyses were mainly used to characterize these deposits. From the Late Eocene until the Late Oligocene central-western Poland area was a marginal part of the NW European Tertiary Basin. For this time interval five informal lithostratigraphical units have been determined: the Pomorze, Lower Mosina, Czempiń, Upper Mosina and Leszno "formations" and additionally the Kaolinite Sand Unit. Their correlation is based on lithological features obtained from archival descriptions of borehole profiles. Deposits from boreholes and newly discovered exposures are mainly marine while only the Czempiń "Formation", with lignite intercalations, represent a non-marine environment. These findings help reconstruct the structural and palaeogeographic evolution of the eastern, marginal fragment of the NW European Tertiary Basin. The succession shows evidence of at least four interregional transgressive-regressive cycles. Moreover, the present-day extent of the Paleogene deposits has been determined much more precisely. The southern limit of marine sedimentation in Paleogene times should be pushed at least a few tens of kilometres south in the vicinity of Konin and Turek, central-western Poland.