Molčan Matejová M., Reháková D., Aubrecht R., Ledvényiová L. & Měchová L., 2022: Unusual microfacies character of the Pieniny Limestone in the Orava sector of the Pieniny Klippen Belt. Acta Geologica Slovaca, 14, 1, 71–84.

Unusual microfacies character of the Pieniny Limestone in the Orava sector of the Pieniny Klippen Belt

Marína Molčan Matejová¹, Daniela Reháková¹, Roman Aubrecht^1,4, Lucia Ledvényiová² & Lucie Měchová³

¹Department of Geology and Paleontology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina G, 842 15 Bratislava, Slovakia; marina.matejova@uniba.sk, roman.aubrecht@uniba.sk, daniela.rehakova@uniba.sk
²College of Mining and Geology, Technical University of Ostrava, 17 listopadu 15, 708 00 Ostrava-Poruba, Czech Republic; lucia.ledvenyiova@gmail.com
³Institute of Geological Engineering, Technical University of Ostrava, 17. listopadu 15, 708 00 Ostrava-Poruba, Czech Republic
⁴Earth Science Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 845 28 Bratislava, Slovakia

Abstract

he Pieniny Limestone Formation is a significant formation representing the pelagic sedimentation during the Late Jurassic to Early Cretaceous in numerous units of the Pieniny Klippen Belt. On the hills over Revišné, in the Orava sector of the Pieniny Klippen Belt, a distinctive klippe was sampled and biostratigraphically analysed in detail. The klippe consists of the “biancone” type limestones of Early Tithonian to Late Valanginian age. The age range was determined by calcareous dinoflagellates, radiolarians, and aptychi. The section is remarkable by mostly radiolarian and radiolarian-spiculitic microfacies that prevail through the entire Revišné 1 section; the calpionellid to calpionellid-radiolarian microfacies, which typically occurs in the “biancone” facies of the Oravic successions is surprisingly lacking. The samples contain only very rare calpionellids and no calpionellid zones or subzones could be determined. Moreover, probably due to a tectonic reduction, there is a missing interval encompassing microfossil zones of the Lower Tithonian and Lower Beriassian (the calcareous dinoflagellate zones Tenuis, Fortis, Proxima, Fusca, Waneri and Minuta are absent). Lower Tithonian was determined solely based on dinoflagellate cysts, proving Tithonica and Malmica zones. Younger part of the section, just above the discontinuity, was dated to the Upper Beriassian (Vogleri Zone) by the onset of Colomisphaera vogleri and Stomiosphaera wanneri. Lower Valanginian (Valanginiana Zone) was determined by the occurrence of Colomisphaera lucida, Colomisphaera heliosphaera, Carpistomiosphaera valanginiana and Stomiosphaera echinata. Apart from dinoflagellates, the Late Valanginian age of the youngest layers was also proved by lamellaptychi. Predominance of radiolarians (approximately 30-40% in all thin sections), missing calpionellids, and conformable lithology and microfacies suggest that the studied beds sedimented in the deepest parts of the basin with relatively stable conditions. The lack of dinocyst and calpionellid zones in the lower part of the section is interpreted by the tectonic reduction of the sediments, resulting from a younger local tectonic event. The specific character of the described limestones reflects microfacies variability of the Pieniny Limestone Formation in the Oravic successions.

Key words: Pieniny Klippen Belt, Pieniny Limestone Formation, Late Jurassic, Early Cretaceous, microfacies, dinocysts, radiolarians, lamellaptychi

Manuscript received: 2021-11-12

Revised version accepted: 2022-06-15