Datafit for seismic (left-hand panel) and thermodynamic (right-hand panel) inversions. Shown are fits of PP (a, e) and SS waveform stacks (b, f) and Rayleigh wave phase velocities (c, g) for cap #54 (Indian Ocean). Panels (d) and (h) show phase velocity residuals relative to the observations (in per cent), that is positive/negative residuals indicate higher/lower synthetic phase velocities, respectively. The thermodynamic datafit is shown for inversions based on an equilibrium assemblage (EA) and mechanical mixture (MM) model. Synthetics are randomly picked from the posterior distribution. Entire datafit sections for all caps are shown in Figs S25–S34.