Geochemical evolution of volcanism of the Matua Island (Central Kuril Islands)
The first comprehensive geochemical study of the Matua Island allows the authors to reveal the general stages of the magmatic evolution of the subduction system. The petrological similarity of the studied rocks with those from the northern Kuril Islands testifies that the formation of both of them above the “hot”, geochemically enriched, but isotopically depleted mantle of southern Kamchatka. The change in the composition of Matua island volcanic rocks in the Pleistocene-Holocene gives ground to suggest the change of the geodynamic regime in the formation of the subduction system. To account for the similar regularity previously established in the southern Kuril islands, Mutnovsky and Gorely volcanoes of the southern Kamchatka, a global Pleistocene-Holocene tectonic event in the geological history of the Kuril-Kamchatka subduction system may be proposed. The presence of “adakite-like” tephra among volcanoclasts of the Sarychev Pick volcano provides the important information about magma genesis of the Kuril island arc, such as relatively high temperatures on the subduction plate surface and involvement of basalts from the upper oceanic plate into magma genesis.