A PARTICULAR TYPE OF CATASTROPHIC EXPLOSIVE ERUPTIONS WITH REFERENCE TO THE HOLOCENE SUBCALDERA ERUPTIONS AT KHANGAR, KHODUTKA MAAR, AND BARANIY AMFITEATR VOLCANOES IN KAMCHATKA

Abstract

The catastrophic explosive eruptions at Khangar ~7000 14C years ago, Khodutka Maar ~2800 14C years ago, and Baraniy Amfiteatr ~1500 14C years ago are classified as a particular type of subcaldera eruptions. Although they resembled caldera-forming eruptions in terms of dynamics and the volume, habit, facies, and composition of the pyroclastics, they were not accompanied by the formation of collapse calderas. The discrepancy between the caldera habitat of the pyroclastics and the type of the eruption vent (explosive crater) can be explained by the considerable depths of acid magma reservoirs that were 'galvanized' by the injection of high-temperature basalt magma into them. It is believed that there subcaldera eruption had a considerable climatic impact and left their signatures as synchronous acid peaks in the Greenland ice sheet.