Preliminary report for the geochemical characteristics of Quaternary magma from Futagoyama volcano, northeast Kyushu, Japan

Abstract

We determined the trace element compositions of Quaternary magma from Futagoyama volcano, northeast Kyushu, Japan. From the results, geochemical characteristics of island arc magma are observed, such as enrichment of LILE and negative anomaly of Nb. Primitive mantle normalized trace element pattern is similar that of Himeshima volcanic group. Sr/Y ratios of Himeshima are 5 to 70, and most of the ratios are >25. The Sr/Y ratio of Futagoyama is 30 indicating the signature of adakite. From these observations, adakite is distributed from Himeshima to Futagoyama to Yufu Ttsurumi, and the duration of the activity is from 1.5 - 1.1 Ms to <10kyr.