Fig. 10
a Logarithm of the ratio of the total dissolved Mg content in mantle-derived fluid [log CMg (mantle)] to the total dissolved Si content in metapelite-derived fluid [log CSi (crust)] for the P–T conditions along the upper surface of the slab in the NE Japan, Nankai, and Cascadia subduction zones [log MS ratio = log CMg (mantle)/log CSi (crust)]. Labels 1 and 2 indicate the P–T conditions for the thermodynamic calculation of fluid-rock interaction in (b–c). The P–T paths along the upper surface of the slab in the NE Japan, Nankai, and Cascadia subduction zones are from van Keken et al. (2018; Fig. 3). b–e Results of the thermodynamic calculations on the infiltration of fluids equilibrated with ultramafic rocks into metasediments (left panel) and on the infiltration of fluids equilibrated with metasediments into ultramafic rocks (right panel). b Mineral mode (%) and c mass change (g) of 1 kg protolith with respect to moles of fluid added to 1 kg rock in NE Japan (230 °C and 1.0GPa; point 1 in Fig. 10a). d Mineral mode (%) and e mass change (g) of 1 kg protolith with respect to moles of fluid added to 1 kg rock in Nankai (468 °C and 1.0GPa; point 2 in Fig. 10a). F/R ratio means the fluid-to-rock mass ratio. The results for Cascadia at the same pressure (519 °C and 1.0 GPa) are shown in Additional file 1: Fig. S2. For the F/R ratio labeled by “Not calculated”, the thermodynamic calculations were failed due to the convergent problem. Arg: aragonite, Cpx: clinopyroxene, Ms: muscovite, Lws: lawsonite, Stp: stilpnomelane, Qz: quartz,Amp: amphibole, Chl: chlorite, Tlc: talc, Atg: antigorite, Ep: epidote, Ab: albite, Bt: biotite, Mgs: magnesite, Dol: dolomite