AGE OF THE HIGH-TEMPERATURE GNEISS CORE OF THE CENTRAL CAUCASUS

Abstract

Different pre-Mesozoic formations dominated by metamorphic complexes are widespread in the mountainous Central Caucasus. Knowledge of their ages is essential for interpretation of the pre-Mesozoic structure, evolution, and geodynamics of the Crimean–Caucasian segment at the southern active margin of Eurasia. These issues are still highly debatable. It is widely accepted that metamorphic rocks are of Proterozoic age in all zones of the Central Caucasus. The most widespread gneiss–migmatite complex (GMC) of the Main Range composed of para- and orthogneisses, amphibolites, and migmatites, which outcrop in its northern part, is also attributed to the Proterozoic based on the following facts: (1) its location in the deepest (core) part of the range; (2) the highest grade of metamorphism in the Greater Caucasus corresponding to high-temperature stages of the amphibolite facies; and (3) several U–Pb zircon ages corresponding to the Precambrian, although they have remained debatable for a long time.