Pavlova O. Geochronology of diaphthorically altered Paleoproterozoic granitoids of the Volyn megablock of the Ukrainian shield

Diaphthorically altered Paleoproterozoic granitoids of Volyn megablock of the Ukrainian shield are investigated. Microprobe geochemical investigations of biotites from granitoids as well as geochronometrical research of biotite and amphiboles by K-Ar and zircon by U-Pb methods were carried out. Complex of structure-genetical and geochronometrical researches were made. Certain geochemical features of biotites from granitoides of Volyn megablock were established. Structure-genetical characteristics of diaphthorically altered Paleoproterozoic granitoides of this megablock were established. It is revealed that all granitoids were altered at different degrees in zones of tectonic dislocations at conditions corresponding to epidoth-amphibolite facies of metamorphism according to TP- parametrs. It is istablished that the results of isotopic dating of biotite (by K-Ar method) taken together with structural-genetical analyses of mineral can be used for the investigations of the age of any biotite-bearing Precambrian rock of both magmatic and metamorphic origin. Statistical analyses of geochronometrical information for discovering sequence, stages, intensity and thermal regime of metamorphic for certain crystalline rocks and even for the whole regions have been used.