Uwagi o biostratygrafii serii menilitowo-krośnieńskiej w polskich Karpatach zewnętrznych

Abstract

 Omówiono trzy charakterystyczne zespoły otwornic z utworów serii menilitowo-krośnieńskiej, głownie z jednostki skolskiej polskich Karpat zewnętrznych (oligocen – ?dolny miocen). Ustalono po raz pierwszy pewne następstwo stratygraficzne tych zespołów. Stwierdzono, że zespoły otwornic z serii menilitowo-krośnieńskiej jednostki skolskiej są identyczne jak występujące w tych samych warstwach innych jednostek facjalnych. SOME REMARKS ON BIOSTRATIGRAPHY OF THE MENILLITE-KROSNO SERIESIN THE POLISH OUTER CARPATHIANS The Menillite and Krosno Beds are the youngest in the succession of Tertiary flysch deposits in the Polish Outer Carpathians. The studies on small foraminifers, carried out in the last few years, showed the presence of planktonic foraminifer assemblages (I–III, tab. 1,2) in these deposits.The assemblage I – comprising Turborotalia liverovskae (Bykova), Globigerina praebulloidesStreszczenie Blow and G. officialis Subbotina (Lower Rupelian) – was found in lower part of the Menillite Beds in all stratigraphic-facies units of the Carpathians. Fairly common characteristic species of that assemblage are accompanied by G. angustiumbilicata Bolli, Turborotalia permicra (Blow et Banner), T. brevispira (Subbotina), T. nana (Bolli), and Chiloguembelina gracillima (Andreae). Some species of that asssmblage are already present in the Sub-menillite Globigerina Marls, underlying the Menillite–Krosno Series.The assemblage II – with Turborotalia brevispira (Subbotina), Globigerina praebulloides Blow and G. officialis Subbotina (Upper Rupelian) – was found in upper part of the Menillite Beds in the Skole Unit and the Lower Krosno Beds in the remaining stratigraphic-facies units. Besides common characteristic species, the assemblage comprises Globigerina ciperoensis Bolli and G. postcretacea Mjatliuk and species appearing for the first time in the assemblage I. In strata characterized by the assemblage II, Turborotalia liverovskae (Bykova) gradually disappears and T. inaequiconica (Subbotina), younger synonym of T. siakensis (Le Roy), appears.The assemblage III – with Turborotalia inaequiconica (Subbotina) and Cassigerinella chipolensis (Cushman et Ponton) (Chattian – ? Aquitanian) – occurs in the top part of the Menillite Beds in the Skole Unit and middle and upper parts of the Krosno Beds of that and other stratigraphic-facies units of the Polish Outer Carpathians. The characteristic species of that assemblage are accompanied by Globigerina praebulloides Blow, G. occulusa Blow et Banner, G. ouachitaensis Howe et Wallace, G. ciperoensis Boili, Turborotalia nana (Bolli), T. brevispira (Subbotina). In the uppermost part of the flysch succession, there were found Globorotalia zealandica Hornibrook, Turborotalia pseudokugleri Blow, T. semivera (Hornibrook) and Globigerina woodi connecta Jenkins, indicative of the proximity of the Oligocene-Miocene boundary. The planktonic species are accompanied by similarly differentiated microfauna of benthic foraminifers.