Bulk conductivity versus fluid fraction at various salinities at 800 K and 1 GPa. The variables were calculated from the HS + model (dotted lines), cube model (solid lines), and Archie’s law (dashed-dotted lines). The solid circles show experimental data points obtained in this study. The open circle and open squares show the conductivities of NaCl with salinity of 0.3 wt.% at 0.4 GPa and 800 K (Quist and Marshall 1968) and KCl with salinities of 3.6, 13.5, and 24.7 wt.% at 0.3 GPa and 773 K (Nesbitt 1993), respectively. The gray region indicates the range of the crustal high-conductivity anomalies (10−3 to 10−1 S/m).