The Role of Fractional Crystallization in the Formation of Neogene Volcanism in the Central Part of the Lesser Caucasus

Abstract

The role of the process of fractional crystallization in the formation of Neogene volcanism in the central part of the Lesser Caucasus is discussed in the article. It was found that in the formation of rocks of the andesite-dasite-rhyolite association found in the central part of the Lesser Caucasus, the role of rock-forming minerals in intermediate foci - plagioclase, clinopyroxene, amphibole, olso titanium magnetite, apatite is quite large. Based on computer modeling, it was determined that the calcium-alkali trend of the andesite-dasite-riolit series is controlled not only by the fractionation of magnetite, but also by the crystallization of hornblende with a high Fe/Mg ratio and unsaturated with SiO2. Hornblen's early crystallization is a key factor in the formation of the calc-alkaline series during the evolution of Neogene magmatism. Keywords: Central part of the; Lesser Caucasus; Neogene volcanism; Fractional crystallization; Hornblende crystallization.