Figure F6. A. K2O vs. SiO2 of lavas of the volcanic front (Oshima, Miyake-jima, Mikura-jima, Hachijojima, Aoga-shima, Myojin Knoll, Sumisu, and Torishima), the rear arc (Kan’ei, Manji, Enpo, Genroku, and Horeki), and average continental crust (Rudnick and Gao, 2004). Data from Tamura and Tatsumi (2002) and references therein, Machida and Ishii (2003), Tamura et al. (2005, 2007), and Machida (unpubl. data). Data for the Enpo chain are similar to other rear-arc type magmas. No data are shown for rift-type magmas (<3 Ma) for reasons of clarity. B. Chondrite-normalized rare earth element (REE) abundances in the volcanic front and the rear-arc basalts and andesites and average continental crust (Rudnick and Gao, 2004). Volcanic front (Oshima, Miyake-jima, Hachijojima, Aoga-shima, Sumisu, and Torishima) data from Taylor and Nesbitt (1998) and Tamura et al. (2005, 2007). Rear-arc (Kan’ei, Manji, Enpo, Genroku, and Horeki) data from Ishizuka et al. (2003b), Hochstaedter et al. (2001), Machida and Ishii (2003), and Ishizuka (unpubl. data). Data for the Enpo chain similar to other rear-arc type magmas. Rear-arc patterns are similar to average continental crust in heavy REE.
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