Geochronology of Neogene-Quaternary volcanism of the Geghama Highland (Lesser Caucasus, Armenia)

Abstract

This work continues the systemic isotopic‐geochronological studies of Late Cenozoic volcanism in the Lesser Caucasus [1‐5] undertaken to elaborate the general regional scale of magmatic activity in this region during the Neogene‐Quaternary and to establish neovolcanic centers potentially hazardous in terms of possible catastrophic eruptions. The young magmatism in the Caucasian segment of the Alpine belt that developed in the course of collision between the Eurasian and Arabian lithospheric plates is genetically related to the activity of the mantle “hot field” [6], which determined the prevalence of basic rocks among volcanics. The most intense pulses of volcanic activity during the Neogene‐Quaternary are recorded in the Lesser Caucasus and eastern Anatolia, while young igneous rocks are distributed only in small areas of the Greater Caucasus. The Lesser Caucasus volcanic province, which extends in the arcuate manner from Ajaria to Nagornyi Karabakh and includes abundant Neogene‐Quaternary volcanics [7], is divided into six neovolcanic areas (from the northwest to southeast): Erusheti‐Arsiani, Javakheti, Aragats, Geghama, Vardenis, and Syunik. Young volcanics of the Lesser Caucasus are highly variable in terms of their chemical composition with varieties of normal and elevated alkalinity being most abundant. Our previous studies [1‐5] provided ages for Neogene‐Quaternary igneous rocks from several reference volcanic centers of the Aragats and Javakheti areas. These dates allowed us to define regional geochronological scales for young volcanism. In this work, we consider isotopic‐geochronological data obtained for Neogene‐Quaternary igneous rocks from the Geghama neovolcanic area located in the territory of the Republic