Two Stages of Explosive Volcanism of the Elbrus Area: Geochronology, Petrochemical and Isotopic–Geochemical Characteristics of Volcanic Rocks, and Their Role in the Neogene–Quaternary Evolution of the Greater Caucasus

摘要

The chronology of evolution of the young explosive volcanism in the Elbrus area of the Greater Caucasus is revealed. The isotopic–geochronological data indicate that ignimbrites and associated volcanic rocks were formed during the Middle Pliocene (3.0–2.75 Ma) and Early Pleistocene (0.84–0.70 Ma) stages of magmatic activity of the Greater Caucasus. The presence of two groups of pyroclastic rocks significantly different in age and analysis of their location indicate two spatially combined volcanic centers different in age in this part of the Elbrus volcanic area: Pliocene Tyrnyauz center localized in the eastern and southern parts and Quaternary Elbrus volcanic center which is the only newest center of volcanic activity both in the Elbrus and in the entire neovolcanic area. The analysis of chronology of magmatic events and compositional peculiarities of the young igneous rocks of the Elbrus area for the period from 3 Ma to the Holocene shows that the caldera stage of the evolution of the Elbrus Volcano has not come yet and future catastrophic magmatism is highly possible.