Figure 2

Relation between H ₂ O concentration in melt and (a) anorthite content of coexisting near-liquidus plagioclase or (b)${\mathit{K}}_{\mathbf{D}\mathbf{pl}\mathbf{-}\mathbf{melt}}^{\mathbf{Ca}\mathbf{-}\mathbf{Na}}$. At 1.0, 1.5, and 2.0 kbar. (b) Dashed lines represent the range in typical basalt from the Northeast Japan and Izu arcs (0.32 < Al₂O₃/SiO₂ < 0.39). When the H₂O content was estimated by Equation 1, the expected error was within that indicated by the dashed lines. Source: Berndt et al. (2005) and Sisson TW et al. 1993b.