Fig. 3: Models of bridgmanite transformation kinetics in D″.

a Transformation characteristic times \(\tau\) measured in the experiments vs. P and T. The figure also indicates the final weight proportions of pPv by the size of the symbol. Solid line: reference for the Pv/pPv phase boundary (defined by a reference point at \(P=128\) GPa, \(T=3300\) K, and a Clapeyron slope of 8.5 MPa K\({}^{-1}\)). Inset: \(\pm\! 1\sigma\) uncertainties on \(P\) and \(T\). Solid and dashed lines represent relative and absolute uncertainties on \(P\), respectively. b–d Extrapolated transformation characteristic times vs. \(P\) and \(T\) for the shear (b) or nucleation and growth (c, d) phase transformations models. Red, green, and blue dashed lines are the hot, warm and cold geotherms of ref. ⁵. The shear transformation model is independent of grain size. d Extrapolation of the nucleation and growth model to mm grain sizes.