First fission-track dating of zircons from Mesozoic complexes of the Crimea

Abstract

The fission-track dating of detrital zircon from Mesozoic terrigenous complexes of the Crimean mountains has been carried out for the first time. A young zircon population from the Tavria Group of sandstones of the Yaman ravine was dated at 220.1 ± 12.6 Ma, and the zircon population from the same deposits of the Crimea’s southern coast, at 193.6 ± 13.1, 167.1 ± 12.1, and 154.0 ± 10.2 Ma. Sandstones from the lowermost parts of the Demerdzhi Formation on Mount Yuzhnaya Demerdzhi comprise the Middle Jurassic young zircon population (169.9 ± 8.6 Ma). The age of the young zircon population from the Chenka Formation in the region of the Settlement of Observatoriya corresponds to the initial Middle Jurassic (178.9 ± 9.1 Ma). The timing of the cooling of the Mount Kastel massif was established at 149.0 ± 10.9 Ma. In all the considered cases, the age of terrigenous complexes is close to the age of enclosed zircons. Volcanic and/or magmatic rocks that formed synchronously with accumulation of terrigenous complexes in the sedimentary basin are likely to have been sources of zircons. Hence, the data obtained allow the timing of the Triassic-Jurassic magmatism in the Crimean mountains to be refined and three stages of magmatism to be distinguished: Late Triassic (Carnian?), poorly expressed Early Jurassic, and Middle Jurassic (Aalenian-Bathonian).