New Findings of Foraminifers and Age Correction of Callovian (Middle Jurassic) Marine Deposits of the Western Caucasus

A comprehensive understanding of Callovian (Middle Jurassic, Mesozoic) sedimentation and paleogeography requires examination of marine deposits of this stage across multiple geological domains on Earth. The Western Caucasus is a key region for Callovian studies in the central Northern Neotethys, but the age of its Callovian marine deposits remains uncertain. A reference section was examined, and a horizon containing foraminifers was found in the Kamennomostskaya Formation. The assemblage comprises both agglutinated and calcareous forms and is dominated by Labalina costata (Antonova, 1958). Data from other regions permit hypothesizing an Early Callovian age for the horizon based on the foraminifers. Considering recent findings of macro- and microfossils, the age of the entire Kamennomostskaya Formation can be constrained to the Early Callovian—older than previously thought. It is proposed that the Middle Callovian corresponds locally to a hiatus. This age revision facilitates a comparison between regional and global sea-level changes. Apparently, there was eustatic control over Early Callovian marine sedimentation in the Western Caucasus.