Evolution of the interior for different initial mantle temperatures between 1600 and 1800 K, initial water concentrations () between 250 and 1000 ppm, and an oxygen fugacity corresponding to the IW buffer. Panel a: Mantle temperature is shown; b) corresponding mantle viscosity is shown; c) thickness of the crust (solid lines), the stagnant lid (dashed lines), and distribution of the melt zone and melt fraction (coloured area) are shown; and d) water concentration in the mantle is shown. The different colours, from grey to dark blue, indicate increasing initial water concentrations; the thick black lines in the four panels and the coloured melt zone in panel c indicate the reference model (ref.) with T_m,0 = 1700 K, ppm, and f_O2 at the IW buffer. The different initial mantle temperatures, which can be identified in panel a, are not indicated with distinct colours.