Barnasiówka Radiolarian Shale Formation - a new lithostratigraphic unit in the Upper Cenomanian-lowermost Turonian of the Polish Outer Carpathians (Silesian Series)

A new lithostratigraphic unit - the Barnasiówka Radiolarian Shale Formation - is herein defined. It belongs to the Silesian Series of the Outer Carpathians. The formation consists of biosiliceous deposits rich in organic matter, laid down around the Cenomanian-Turonian boundary. The formation includes, from bottom to top: (1) a series of green to black, calcareous and siliceous shales, alternating with layers of chert, siliceous siltstone and sandstone (up to 10 m thick); (2) a series of green to black, argillaceous to siliceous shales, intercalated with tuffites, bentonites, and a ferromanganese layer (up to 9 cm thick) in its middle part (up to 3.2 m thick); (3) a series of green and red, siliceous siltstones and cherts with intercalations of non-calcareous green shales and benthonites (up to 2 m thick). The total thickness of the formation ranges from 0.5 m in the eastern part (reduced tectonically?) up to about 14-15 m in the middle and the western parts of the Silesian Nappe, due to the increase in the number and thickness of turbidite intercalations. The formation represents the Holocryptocanium barbui - Holocryptocanium tuberculatum through the Alie-vium superbum radiolarian zones and the Uvigerinammina praejankoi-Uvigerinammina jankoi foraminiferal zones, which correspond to the Upper Cenomanian through the lowermost Turonian. Microfacies and geochemical characteristics of the distinguished lithological types are presented in this paper, based on recent studies and published data. The described formation has been compared and correlated with deposits of similar age from other tectonic- facies units of the Outer Carpathians in Poland and Ukraine.