International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Biostratigraphy and paleoenvironmental changes on the transition from the Menilite to Krosno lithofacies (Western Carpathians, Czech Republic)

Published: Jun 2007

Pages: 237 - 262


Abstract: Study of microfossils and calcareous nannofossils confirmed the diachronous onset of the Krosno lithofacies. In the Fore-Magura Unit the Reticulofenestra ornata bloom correlated with NP24 Zone (lower Upper Oligocene) was recognized within this facies while in the Zdanice-Subsilesian Unit in the underlying Menilite lithofacies. Onset of the Krosno lithofacies in the external Pouzdøany Unit is attributed to the Lower Miocene, NN3 Zone. The Zagórz Limestone intercalations were found as an important biostratigraphic horizon for the lower part of the Krosno lithofacies in the Zdanice-Subsilesian Unit and is attributed to NP25 Zone. Microplankton blooms (Limacina sp., bivalve juveniles, clavate planktonic foraminifers Beella and Bolliella, radiolarians, prasinophyte cysts, planktonic diatoms) and calcareous nannoplankton blooms (Cyclicargolithus spp., R. ornata) or abundances of some taxa (Pontosphaera spp., Reticulofenestra minuta, Syracosphaera sp.) are characteristic of the upper Menilite and lower Krosno lithofacies and reflect rearrangement of Carpathian orogenic zone, isolation of foreland basins and development of “Protoparatethys”.

Keywords: Oligocene, Lower Miocene, Outer Flysch Carpathians, biostratigraphy, paleoenvironment, plankton blooms, foraminifers, calcareous nannofossil

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