Fig. 4: Cumulative frequency plots of Boku and Ziway olivine Fe–Mg interdiffusion timescales.

a–f, Diffusion-only (a–d) and growth–diffusion (e and f) models (n is the number of profiles). Diffusion-only timescales (log-mean ± 1 log-standard-deviation) are separated by olivine population (Pop.), with population 1 timescales illustrated in a and c, and population 2 timescales in b and d; crystals of the other population at the same locality are included as faded markers and curves. The growth–diffusion timescales illustrated in e and f (Bou and Ziway, respectively) include both populations. Faded curves in e and f represent all diffusion-only timescales at Boku and Ziway, respectively. Diffusion-only timescales are calculated at fixed temperatures, shown within a–d. Growth–diffusion timescales are obtained at variable initial olivine–melt system temperature (Methods). Kernel density curves in log-space use Gaussian approximation to determine bandwidth, and relative probability density is consistent across all panels. Note that some timescales are recorded from the same crystal.