Ophiolite association of Cape Fiolent (western part of the Mountainous Crimea) – the upper age constraint according to the U-Pb isotope dating of plagiorhyolites (Monakh Cliff)

Abstract

The article presents the results of U-Pb isotope dating (SHRIMP-II, VSEGEI, Saint Petersburg) of zircon crystals extracted from plagiorhyolites of the Monakh Cliff in the area of Cape Fiolent in the western part of the Mountainous Crimea (southern suburb of Sevastopol). a concordant age estimate of 168.3±1.3 Ma was obtained from 20 zircon crystals. It exactly corresponds to the Bajocian/Bathonian boundary of the Middle Jurassic according to the International Chronostratigraphic Chart (February 2022 version). The available results of isotope dating of igneous rocks from the Mountainous Crimea, as well as their geochemical typification are synthesised. The plagiorhyolites of the Monakh Cliff in the area of Cape Fiolent are spatially, and most likely paragenetically, associated with the wallrock (Cape Vinogradny) and ore (Heraclea Plateau on the cognominal peninsula) massive sulphide formations, as well as pillow basalts, gabbroids, and serpentinized hyperbasites, combined into the ophiolite association of Cape Fiolent. The obtained dating is the upper age limit for the entire ophiolite association of Cape Fiolent.