MAGMATITES OF THE KASTEL MOUNTAIN AS A LOCAL SOURCE OF DETRITAL ZIRCONS FOR THE DEMERDZHI FORMATION (SOUTHERN DEMERDZHI MOUNTAIN), MOUNTAINOUS CRIMEA

The paper presents the first results of U-Pb LA-ICP-MS isotope dating (GIN RAS) of accessory zircon from magmatites of the Kastel Mountain and detrital zircons from the sandy matrix of conglomerates of the lower subformation of the Demerdzhi formation (vicinity of the Southern Demerdzhi Mountain). The three age estimates – (±1σ) – 147±1, 156±1 and 167±1 Ma, – obtained for granitoids of the Kastel intrusive, are consistent with the concept of its longterm and multi-stage magmatic evolution. The age of 167±1 Ma coincides with the final stages of the episode of bimodal magmatism widespread throughout the Mountainous Crimea from the Cape Fiolent to the Karadag. The intrusion of the first portions of basic magma near this time boundary had initiated the Kastel intrusion formation. The fractionation of basic magma during the second stage about 156±1 Ma gave rise to the formation of silicic melts from which the plagiogranites, comprising most of Kastel intrusive, were crystallized. About 147±1 Ma, the residual portions of silicic melts as small aplite veins intervened in the main volume of the intrusive and the adjacent host rocks. A comparison was made of the currently known ages of magmatites and detrital zircons from sandy rocks of some of the Triassic-Jurassic sedimentary strata of the Mountainous Crimes in order to clarify the source areas of the materials constituting the stratified rocks. It was shown that the magmatites of Kastel Mountain were a local source for the Demerdzhi formation.