Lithostratigraphy and biostratigraphy of the Upper Albian-Lower/Middle Eocene flysch deposits in the Bystrica and Rača subunits of the Magura Nappe (Beskid Wyspowy and Gorce Ranges; Poland)

Abstract

Lito- i biostratygrafia utworów fliszowych górnego albu-dolnego/środkowego eocenu w jednostce bystrzyckiej i raczańskiej płaszczowiny magurskiej w Beskidzie Wyspowym i Gorcach (Zachodnie Karpaty fliszowe) Lithostratigraphy and biostratigraphy of the Bystrica and Rača subunits of the Magura Nappe have been studied in the southern part of the Beskid Wyspowy Range and on the northern slopes of the Gorce Range (Polish part of the Western Flysch Carpathians). Six new lithostratigraphic units (Jasień Formation, Białe Formation, Jaworzynka Formation, Szczawina Sandstone Formation, Krzysztonów Member, and Ropianka Formation) of the Upper Albian–Palaeocene age have been established, and five other units (Malinowa Shale Formation, Hałuszowa Formation, Łabowa Shale Formation, Beloveza Formation, Bystrica Formation) have been additionally described. The newly created formations as well as the Malinowa Shale Formation and the Hałuszowa Formation have been included to a new Mogielica Group of units (Upper Albian–Palaeocene). This group of units passes upwards into the Beskid Group (Eocene–Oligocene).The Mogielica Group, spanning over 40 myrs, represents the turbidite depositional system, separated by highstand variegated clays which can be correlated with minor sequences in terms of sequence stratigraphy. The following biostratigraphic zones have been recognised in the Cretaceous–Lower/Middle Eocene deposits: Plectorecurvoides alternans, Bulbobaculites problematicus, Uvigerinammina jankoi, U. jankoi-C. gigantea, Caudammina gigantea, Remesella varians, Rzehakina fisistomata, Glomospira div. sp., and Saccamminoides carpathicus. A few lithostratigraphic units consisting of calcareous sediments have been correlated with the standard calcareous nannoplankton zonation and the chronostratigraphy.