VOLCANISM OF THE EARLY FORMATION STAGE OF ITURUP ISLAND (GREAT KURILE CHAIN)

The article presents new petrogeochemical data on the Middle Miocene-Pliocene volcanic rocks from central part of Iturup Island (Great Kurile Chain). It is shown that volcanism Miocene-Early Pliocene age in took place a suprasubduction setting. distribution high field strength elements (HFSE) and their ratio basaltoids indicate formation upon partial melting depleted upper mantle, while enrichment with large ionic lithophilic (LILE) indicates both fluid mantle additive introduced into melts during evolution primary magma participation low-temperature fluid. established differences composition frontal rear zones due to limited number analyzed samples are considered preliminary. Thus, zone distinguished by higher concentrations Th, Pb, HFSE (Nb, Zr, Y, Hf), relative LREE, pronounced negative Zr Hf anomalies, positive Eu.