Ultramafic Rocks Of The Rakovaya Bay (Eastern Kamchatka): Composition And Geodynamic Classification

Abstract

We present results of detailed mineralogical and geochemical investigations of peridotites from the allochthonous plate in Rakovaya Bay (north of the Gulf of Avacha, Eastern Kamchatka). In geologic position and composition the studied rocks are much similar to ultramafic rocks of other massifs of the East Kamchatkan ophiolite belt and are referred to as restite peridotites of the so-called suprasubduction type, transformed by multistage metamorphism. It is suggested that the peridotites of the Rakovaya Bay, along with ultramafic rocks of the Ganaly Ridge and ultrabasic xenoliths of the Avachinsky Volcano form a linear NW-oriented zone, which spatially coincides with the Avacha-Kolpakova zone of structural deformation and marks the southern margin of the area of occurrence of ophiolite-type ultramafic rocks in Eastern Kamchatka.