Integrated stratigraphy and palaeoenvironmental interpretation of the Upper Kimmeridgian to Lower Berriasian pelagic sequences of the Velykyi Kamianets section (Pieniny Klippen Belt, Ukraine)

Abstract

A continuous sedimentary and stratigraphic record of Late Kimmeridgian – Early Berriasian age is presented from the pelagic succession from the eastern part of the Pieniny Klippen Belt (Velykyi Kamianets section, Ukraine). The studied section, 26-m-thick, was calibrated using biostratigraphy (calpionellids, calcareous dinocysts, calcareous nannofossils), magnetostratigraphy, stable isotope stratigraphy (δ13C and δ18O) and gamma ray spectrometry. Magnetic polarity zones from M23r to M18n were identified. The magnetostratigraphic calibration of calcareous dinocysts zonation around the Kimmeridgian/Tithonian boundary has been performed for the first time. The Carpistomiosphaera borzai/Committosphaera pulla calcareous dinocyst zonal boundary is situated at the bottom of magnetozone M22n, slightly lower than first occurrence of calcareous nannofossil Conusphaera mexicana minor and higher than the standard Kimmeridgian/Tithonian boundary (M22Ar/M22An; Hybonoticeras beckeri/Hybonoticeras hybonotum Ammonite Zone boundary). The position of the Tithonian/Berriasian boundary in the magnetosubzone M19n2n (Crassicollaria/Calpionella Calpionellid zonal boundary) has been confirmed. A decrease of terrigenous input and an increase of carbonate productivity correlate with increasing sedimentation rates from 0.7 to 1.1 m/Myr in the Upper Kimmeridgian (M23r to M22r) to 5–7 m/Myr in the uppermost Tithonian and Lower Berriasian (M19n to M18n). Transition between the Saccocoma and calpionellid microfacies occurs in a narrow time interval, mostly within polarity subchron M20n1r. This event is traceable in similar stratigraphic position in several Western Tethyan sections and correlates perfectly with Nannofossil Calcification Event of the early Late Tithonian.