Olivine diffusion chronometry: recent developments and future directions

Diffusion chronometry is used to estimate timescales of magmatic processes by modeling the relaxation of chemical gradients in volcanic crystals. Using olivine for diffusion chronometry is popular due to its abundance in ultramafic to andesitic magmas, well constrained diffusion rates for key elements (e.g., Fe–Mg) and its ability to resolve timescales from minutes to hundreds of years. In recent years, new programmes for diffusion modeling have been developed, for example DFENS and AUTODIFF, which help to resolve uncertainties surrounding intensive parameters. There has also been an increasing popularity of pairing olivine diffusion chronometry data with geophysical monitoring data, often revealing correlations between diffusion timescales and patterns of pre-eruptive unrest. Other recent developments include the application of olivine diffusion chronometry to exotic magmas like kimberlites, and the increasing use of trace elements such as H+ to resolve rapid ascent. In the future, it is anticipated that there will be advances which capitalize on developments in micro-analytical techniques, for instance the integration of diffusion modeling with X-ray micro-tomography to understand how the 3D shape of olivine affects diffusion. There is also potential for increasing use of trace element diffusion such as Li, Cu and P as knowledge of their diffusion mechanisms improves.