Anyui Volcano in Chukotka: Age, structure, pecularities of rocks’ composition and eruptions

Abstract

⎯The study of lavas and pyroclastics from Anyui Volcano made it possible to reconstruct succession of its eruption events. The age of the eruption is estimated by isotopic methods to be 0.248 ± 0.030 Ma. It is established that the last episode of volcanic activity in northeastern Russia occurred 0.2-0.5 Ma ago (in its continental part, 0.2-0.3 Ma ago). This episode is chronologically close to the last peak in activation of volcanism in the Arctic and Subarctic regions. The absence of features indicating glacial influence on lavas from Anyui Volcano provides grounds for an assumption that no significant glaciations took place in the continental areas of western Chukotka during the last 250 ka.

Catastrophic Processes in River Valleys of Volcanic Regions: Geomorphologist’s Point of View

“…If a river flows in a fault zone with eruption centers of its own (moderatesize shield volcanoes), the latter appears to be within the valley itself. Such phenomena may be seen, for example, in the upper reaches of the Bolshoy and Maly Yenisey, in the Jom-Bolok (Zhom-Bolok) river valley in the Eastern Sayan mountains (Southern Baikal volcanic region, Russia) [15][16][17], in the Bolshoy Anyuy river valley in Chukotka (the Northeast of Russia-see Figure 1) [18].…”

“…As to morphologically distinct valleys, they may be completely or partially filled with lava, with both mainstream and its tributaries dammed. Because of the main river displacement and tributary valleys partly flooded, dammed lakes develop as we can see in the Bolshoy Anyuy river valley in Chukotka (the Northeast of Russia) [18]. They may be considerably deep (up to tens of meters), depending on the initial topographic dissection and the lava thickness.…”