Trace and rare earth elements compositions of granitic rocks in Awaji Island, Southwest Japan Arc

Abstract

Seven trace elements (As, Cr, Ga, Pb, S, Th and V) compositions of granitic rocks in Awaji Island were analyzed using X-ray fluorescence spectrometer at Fukuoka University. Rare earth elements (REE) compositions of some samples of the Granitic Rocks II and III from the island were also determined by instrumental neutron activation analysis at Ehime University. The variation trends of most trace elements of Granitic Rocks I, II and III overlap in Harker’s diagrams. Samples, which were off main trend of major and trace elements in Harker’s diagrams in previous analyses (Yuhara et al., 1998), are often off the variation trends of these trace elements in this study as well. Therefore, these trace elements are also useful for investigation of chemical variations of granitic rocks. Chondrite-normalized REE patterns are enriched in LREE and flat in HREE, and fit in those of granitic rocks in the Ryoke metamorphic belt.