Elbrus active Volcano and its geological history

Abstract

Using the new geological map of the Elbrus Volcano (scale 1:50 000) and the new isotopic datings of the volcanic rocks, the formation history of Elbrus Volcano was found to include a pre-caldera, a caldera, and a post-caldera cycle, during which the modern Elbrus stratovolcano was formed. The Early and The Late period of the volcano's evolution have been identified in the two latter cycles. ignimbrite horizons, as well as breaks in volcanic activity, represented by moraine deposits resting on the surface of lava flows in the same volcanic rock sequence. This map shows that the formation history of the Elbrus Volcano included a pre-caldera cycle, a caldera cycle, the onset of which was marked by a powerful explosive eruption, responsible for the caldera formation, and a post-caldera cycle which resulted in the formation of the present-day Elbrus stratovolcano. It is important to note that each of the two latter cycles in- cluded The Early and The Late period of the evolution of the volcano. No pre-caldera volcanic rocks have been found confidently thus far. These are supposed to include the outliers of tra- chyandesite lava flows found in the mouth of the Khudes River (up to 200 m thick) and of trachybasalt lava flows (120-150 m thick) in the upper reaches of the Tyzyl River.