BASIC MAGMATISM IN THE GEOLOGICAL HISTORY OF THE ELBRUS NEOVOLCANIC AREA, GREATER CAUCASUS: EVIDENCE FROM K-AR AND SR-ND ISOTOPE DATA

Abstract

The age and genesis of basic rocks in the magmatic evolutionary series are of principal significance for regions with predominant acid, mainly crustal volcanism. The appearance of basic volcanic rocks in the rhyolite–dacite volcanic sequences is usually a sensitive indicator of a change in the conditions of magma generation, the involvement of different mantle and/or crustal reservoirs, or a change in the geotectonic and geodynamic settings of the volcanic activity. This is evident from the abundance of Neogene–Quaternary acid and moderately acid volcanism in the Elbrus neovolcanic area, Greater Caucasus.