NANOPLANKTON WAPIENNY I OKRZEMKI ŚRODKOWEGO MIOCENU W REJONIE BUSKA I KAZIMIERZY WIELKIEJ (PÓŁNOCNA CZĘŚĆ ZAPADLISKA PRZEDKARPACKIEGO)

Abstract

MIDDLE MIOCENE CALCAREOUS NANNOFOSSILS AND DIATOMS FROM THE BUSKO AND KAZIMIERZA WIELKA AREA (NORTHERN PART OF THE CARPATHIAN FOREDEEP)Abstract. The results of detailed analysis of calcareous nannoplankton in Miocene deposits from the northern part of the Carpathian Foredeep enabled stratigraphic conclusions. Marly clays of the uppermost part of the Skawina Formation in the Busko (Młyny) PIG-1 borehole section are correlated with the NN5 Sphenolithus heteromorphus Zone that corresponds with the Middle Badenian in the Paratethys and the upper Langhian/ Lower Serravalian in the Mediterranean region. The Krzyżanowice Formation, which includes evaporites (gypsum and clay intercalations), and the Machów Formation represent the NN6 Discoaster exilis Zone. By a comparison with other Paratethyan basins, the Badenian/ Sarmatian boundary is proposed just below a 20-metres thick set of diatomaceous siltstone layers. Among the calcareous nannofossil species, the appearance of Rhabdosphaera poculi Bóna et Kernerne and Rhabdosphaera procera Martini may point to the Lower Sarmatian transgression. Clayey sequences of the Machów Formation in the Kazimierza Wielka (Donosy) PIG-1 borehole correspond with the NN6 Discoaster exilis Zone. Abundance of diatom floras observed in the Busko (Młyny) PIG-1 borehole suggests a proximity of a river mouth that supplied water with nitrates, phosphates and silica. Preservation of delicate siliceous diatom frustules was possible due to rapid deposition of clastic sediments above diatomaceous siltstone.