Abstract

Diffusion chronometry has become increasingly popular in the (igneous) petrologic community over the past two decades as it offers cost-effective yet powerful insight into pre-eruptive magma dynamics and timescales. Any element in any compositionally zoned mineral can be modelled if the respective diffusion rate and magmatic conditions (e.g., temperature) are known; extracted timescales are commonly used to constrain mixing-to-eruption timescales and ascent rates. However, the vast majority of diffusion models only consider the outermost crystal rims as long-term magmatic conditions relevant to crystal interiors are much harder to reconstruct. Here, I present two approaches to diffusion chronometry that allow us to dive deeper into the crystal record and reconstruct magmatic processes beyond the final stages prior to eruption. We will explore how every crystal’s journey towards the surface is different, lasting days to millennia; we will reconstruct how frequent magma recharge into the shallow crust may (or may not) prime a volcano for eruption; and we will fathom whether such long-term injection patterns and durations control eruption magnitude and style. This work highlights the largely untapped potential of diffusion chronometry, and similar studies for volcanoes in different tectonic settings will be crucial to further illuminate deep-seated controls on volcanic activity.