New discovered Late Miocene Verkhneavachinsksya caldera on Eastern Kamchatka

Abstract

During 2009, 2010, 2014 field works the new obtained caldera complex descripted in springheads of Levaya Avacha and Kavycha rivers (Eastern Range, Kamchatka) (Kuvikas & Rogozin, 2009; Leonov et al., 2011). Natural outcrops represented by thick interbedded layers of welded tuffs and ignimbrite (>500 meters thickness). The interbedded layers cover nearly 10 km area (Fig. 1). Volume of pyroclastic deposits was calculated as 220-230 km3, based on size of caldera (Mason et al., 2004). These ejected volumes correspond to strong explosive eruptions with VEI 7 or more. The age of caldera-forming eruption was determined by Ar-Ar method to be of Late Miocene (5.78~5.58 Ma BP).