Pages: 197 - 210
Authors: LILIAN SVABENICKA
Abstract: Calcareous nannofossils were studied in the Karpatian and Lower Badenian deposits of the Carpathian Foredeep, Moravia in view of their use in biostratigraphy. The following nannofossil horizons were recognized: 1. "helicolith" horizon with common Helicosphaera ampliaperta in sandy clays ("schlier") of the Laa Formation, 2. Helicosphaera waltrans horizon in clays and siliciclastic sediments of the Grund Formation and in the basal siliciclastic sediments of the Lower Badenian, and 3. Sphenolithus heteromorphus horizon in clays ("tegel") of Lower Badenian (Moravian) age. In its upper part, oval forms of Coronocyclus nitescens and 5-rayed symmetrical discoasters appear. The occurrence of species H. waltrans is limited to a short stratigraphic interval approximately corresponding to the range of planktonic foraminiferal species Globigerinoides bisphericus and includes the first appearances of Praeorbulina ssp. and Orbulina suturalis. The dominance of helicoliths in the Laa and Grund formations and in the basal siliciclastic sediments of the Lower Badenian gives evidence for a shallow epicontinental sea. Nannofossil enrichment above the Helicosphaera waltrans horizon evidences deepening of depositional area, open-sea conditions, and reflects the Lower Badenian transgression. The problem of correlation of the Central Paratethys regional stages either with the Mediterranean chronostratigraphic scale or with NN zones was discussed.
Keywords: Carpathian Foredeep, Miocene, Karpatian, Badenian, calcareous nannofossils, biostratigraphy, paleoecologyDownload PDF document Show Text Version