Crustal Evolution of a Paleozoic Intra-oceanic Island-Arc-Back-Arc Basin System Constrained by the Geochemistry and Geochronology of the Yakuno Ophiolite, Southwest Japan

Figure 5

Variation diagram of N-MORB normalized La/Nb ratio versus La/Y ratio for the metabasalt in the Yakuno-cho area [11] and the noncumulitic metagabbro in the Asago area [7]. Also plotted for comparative purposes are the compositions of Cenozoic back-arc basin basalts (BABBs) in various areas [31], MORBs (N-MORB [34]; T- and E-MORBs [35]), and island-arc basalt (IAB) [36].