Timescales of magnetite exsolution in plagioclase and implications for paleointensity reliability

Silicate-hosted magnetite particles are often ideal paleomagnetic recorders due to their size and high chemical and magnetic stability. In particular, exsolved magnetite in plagioclase is typically uniformly-sized and fine-grained, however the time-temperature paths of magnetite growth in plagioclase are poorly known. Exsolution models based on Fe diffusion data in plagioclase are used to calculate magnetite growth curves for various combinations of cooling rate and exsolution temperature. These models are used to evaluate the potential for chemical remanence acquisition at certain conditions that may undermine the integrity of paleointensity determinations.