Early Miocene age of Stare Bystre Formation (Magura Nappe, Outer Carpathians, Poland) indicated by the calcareous nannoplankton

Abstract

The area of investigation is situated close to the contact zone between the Pieniny Klippen Belt, Krynica Subunit of the Magura Nappe and the Neogene strata of the Orava–Nowy Targ Intramontane Basin (southern Poland). In the area studied, marine deposits of the Stare Bystre Formation outcrop at the surface where they emerge from beneath freshwater and terrestrial Neogene and Quaternary deposits. Nannofossil assemblages from all samples are strongly dominated by reworked species. The Early Miocene age (NN2) of the Stare Bystre Formation has been determined on the base of the first occurrence of Sphenolithus disbelemnos after Shackleton et al. (2000). During the Late Oligocene (NP25/NN1), the frontal part of Magura Nappe was thrust northwards on to the terminal Krosno flysch basin. The northwards thrusting of the Magura Nappe was accompanied by the formation of the piggy-back basin on the Magura Nappe, filled with the synrorogenic turbidites belonging to the Zawada, Kremná and Stare Bystre formations (NN2).