Structure and the Age of Conglomerates of Mount Southern Demerdzhi Based on the First U/Pb Dating of Detrital Zircons (Upper Jurassic, Crimean Mountains)

U/Pb-isotope dating of detrital zircons from conglomerates of the reference section of the Demerdzhi Formation on the western slope of Mount Southern Demerdzhi was carried out. A cluster of the five youngest, reliably dated zircons with an average age of 154.1 ± 0.73 Ma was revealed, which indicates that the formation of conglomerates overlying the studied layer began to form not earlier than in the Late Kimmeridgian. The dating obtained forces us to reconsider the age of the Demerdzhi Formation, which was previously specified as Oxfordian–Early Kimmeridgian. New data on the age of thecoarse-grained sedimentary rocks of the Crimean Mountains advance concepts about Late Jurassic Cimmerian tectonic activity on the northern Tethys margin.