Origin of alkaline volcanic rocks occuring on the volcanic front of the Izu-Mariana arc, northwest Pacific

Yasuo IKEDA, Makoto YUASA
1994 JOURNAL OF MINERALOGY PETROLOGY AND ECONOMIC GEOLOGY  
Iwojima and adjacent area located in the southern part of the Izu-Ogasawara arc and the northern part of the Mariana arc, alkaline volcanic rocks occurs on the volcanic front . These rocks are characterized by a extreme enrichment in K2O and LILE, relatively constant concentra tions of HFSE, and high 87Sr/86Sr and low 143Nd/144 Nd ratios compared to tholeiitic rocks occuring along the volcanic front of the northern part of the Izu-Ogasawara arc and the southern part of the Mariana arc. The
more » ... ine magma is interpreted to have been generated by partial melting of a mantle source depleted in HFSE but enriched in LILE. The enriched processes in the source mantle might involve additions of LILE-rich H2O fluids released from a mica+apatite metasomat ized mantle.
doi:10.2465/ganko.89.233 fatcat:p4i7qbotqfhgxopiz7dvuj4aja