Résumé
The article investigates fluor-apatite from intermediate igneous rocks of the so-called "sobite" association of the Haisyn Complex in the Ros-Tikych Domain of the Ukrainian Shield. The chemical composition of fluor-apatite, the Sr isotopic composition and the mineral inclusions were examined. In terms of chemical composition, apatites closely resemble stoichiometric fluor-apatite. A significant negative Eu anomaly and the REE pattern are characteristic of apatite from high-Al (peraluminous) granites. On average, the LREE content in fluor-apatite from diorite is higher than that from monzonite. In contrast, the latter contains more Cl, V, Mn, Y, as well as MREE and HREE. Apatite contains numerous mineral inclusions: quartz, amphibole, biotite, K-feldspar, plagioclase, monazite, carbonates, magnetite and graphite. According to the amphibole-plagioclase thermobarometer, the crystallisation temperature of inclusions ranges from 735 to 790 degrees C, with a pressure of ca. 2 kbar. Apatite from diorite exhibits a relatively constant Sr isotopic composition of Sr-87/Sr-86 = 0.71027 +/- 0.00047, whereas apatite from monzonite shows significant variations in the Sr-87/Sr-86 ratio, with an average value of 0.71369 +/- 0.00031. The studied rocks are highly complex, exhibiting features of both peraluminous granitoids and those belonging to the tonalite-trondhjemite-granodiorite association. Fluor-apatites and their inclusions crystallised from the melt, which contained fluid components, primarily water and carbon dioxide. There was a lack of isotopic equilibrium between the melts from which the studied monzonites and diorites crystallized; the diorite melt contained slightly more juvenile components, while the monzonite melt was predominantly a product of the melting of the ancient continental crust.