The Farony Variegated Shale Member – a new lithostratigraphic unit of the Ropianka Formation of the Bystrica Subunit in the Magura Nappe (Outer Western Carpathians), and its documentation in the Orava region

Abstract

This study focuses on the variegated horizon of the Farony Shales occurring in the lower part of the Maastrichtian–Paleocene Ropianka Formation in the Magura Nappe (Outer Western Carpathians). It consists of a shale succession with subordinate thin-bedded sandstones, characterized by the occurrence of red shale laminae and beds. Our analyses of its lateral extent and stratigraphy have constrained its spatial distribution and the timing of sedimentation. The presence of Maastrichtian variegated shales within the Magura Nappe in the Polish and Slovak parts of the Orava region is documented, significantly extending their previously known distribution, formerly restricted to the Gorce Mts. The age of the Farony Shales is assigned to the Lower Maastrichtian, based mainly on the co-occurrence of agglutinated foraminiferal acme assemblages, including Caudammina gigantea (Geroch), Caudammina ovula (Grzybowski), Caudammina excelsa (Dylążanka), and the Saccammina–Placentammina assemblage. This variegated shale succession is formally distinguished herein as the Farony Variegated Shale Member within the Ropianka Formation. Its definition, including the elements required by the rules for establishing new lithostratigraphic units, is given in this paper.