MAFIC AND ULTRAMAFIC INCLUSIONS IN VOLCANIC ROCKS OF A NEW TYPE FOR KAMCHATKA

Abstract

The island arc-type association of plutonic inclusions in Kamchatka is represented most completely on the Avacha and the Shiveluch volcanoes. While studying Late Cenozoic volcanism on the Valovayam River, Kamchatka Isthmus, we found a type of mafic-ultramafic inclusions that are new both for Kamchatka and for island-arc regions in general. These finds with an anomalous composition in volcanic rocks seem to be related to volcanism that occurs in island-arc systems in zones of rifting (sea-floor spreading), involving special silica-undersaturated high-titanium basalt, accompanied by the appearance of inclusions of a special kimberlitic type.