Mid-Cretaceous spicule-rich turbidites in the Silesian Nappe of the Polish Outer Carpathians: radiolarian and foraminiferal biostratigraphy

Authors

  • Marta Bąk Institute of Geological Sciences, Jagiellonian University, Oleandry 2a, PL-30-063 Kraków
  • Krzysztof Bąk Institute of Geography, Cracow Pedagogical University, Podchorążych 2, PL-30-084 Kraków
  • Agnieszka Ciurej Faculty of Geology, Geophysics and Environment Protection, AGH University of Science and Technology, Al. Mickiewicza 30, PL-30-059 Kraków

Keywords:

Outer Carpathians, middle-upper Cenomanian, spicule-rich turbidites, radiolaria, foraminifera, biostratigraphy

Abstract

Spicule-rich turbidites are widespread in mid-Cretaceous deep-water flysch of the Subsilesian and Silesian units in the Polish Outer Carpathians. The spicule-rich material with an admixture of numerous radiolarian and foraminiferal particles was supplied, together with siliciclastic material, from shallow environments, mostly from the northern margin of the Carpathian Basin. We present new data on the age of these deposits in the Silesian Nappe, where they are distinguished as the Mikuszowice Cherts. This unit is composed of medium- and thick-bedded siliciclastic to calcareous turbidites including bluish cherts in their middle and upper parts and of thin non-calcareous hemipelagic shales. We have studied radiolaria and foraminifera from hemipelagic sediments and spicule-rich turbidites, from two continuous sections in the Barnasiówka Range (Beskid Wyspowy Mts.) that included the Mikuszowice Cherts (31 m thick) and their transition into the surrounding units. The age of the Mikuszowice Cherts was determined taking into account the following radiolarian datum events: (1) the occurrence of Praeconocaryomma lipmanae in the entire unit, (2) the FO (first occurrence) of Hemicryptocapsa tuberosa in the upper part of the unit, (3) the FO of Amphipyndax stocki close to the upper boundary of the unit, (4) the FO of Hemicryptocapsa prepolyhedra in the lowermost part of the overlying Barnasiówka Radiolarian Shale Formation. These datum events appear successively in the Western Tethys successions within the Rotalipora cushmani planktonic foraminiferal Zone, which corresponds to the middle and upper Cenomanian (except for its uppermost part). The foraminiferal assemblages, in which such taxa as Rotalipora cf. cushmani, R. cf. greenhornensis, whiteinellids and Uvigerinammina praejankoi successively appear, confirm the mid-late Cenomanian age of the spicule-rich turbidites in the Silesian Nappe. 

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Published

2012-07-02

Issue

Vol. 49 No. 3 (2005)

Section

Articles

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