Composition of sources in the Kinkil complex of Western Kamchatka based on the isotopic-geochemical data

Abstract

The authors studied the isotope-geochemical composition of the Eocene volcanic rocks from the Kinkilsk complex of Western Kamchatka. The peculiarities of the distribution of high field strength and heavy rare-earth elements and their ratio, as well as the isotopic composition of Sr, Nd and Pb suggest the formation of primary melts from depleted or poorly enriched in isotopic composition of the mantle wedge sources in different contaminated quartz-feldspathic sialic sediments. Two types of dependences of εNd in volcanic rocks of the complex on the degree of differentiation of rocks and inter-element relations are revealed. The first is associated with strong contamination of igneous melts with quartz-feldspathic sediments, the second relates to the fractionation of an isotopic (Nd)-enriched magmatic source with weak contamination of the melts with a crustal terrigenous material. The distribution of large-ion (LILE) elements is typical for sources of melts enriched with aqueous fluid and formed with the participation of a substance of a metasomatized mantle wedge.

Keywords

• calc-alkaline volcanism
• active continental margin
• Eocene