Nucleation delay in water-saturated rhyolite during decompression in shallow volcanic systems and its implications for ascent dynamics

Monika K. Rusiecka (1, 2) , Caroline Martel (1, 2)

1 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327
2 Magma - UMR7327

We developed a model of feldspar nucleation delay during decompression in water-saturated rhyolite based on classical nucleation theory (CNT). With the thermodynamic and kinetic parameters proposed in this study, the model agrees with the experimental results of this study to within a factor of two. To account for the variety of conditions encountered by magma during ascent, we propose expanding the model, developed in this study for isothermal decompression, to a wider range of pressures and temperatures (i.e. non-isothermal conditions). We present new measurements of feldspar growth rates during decompression in water-saturated rhyolite, emphasizing the importance of accurately calculating the nucleation delay in order to estimate growth rates. Using these data, we propose a method for estimating the ascent rate of water-saturated rhyolite based on the nucleation delay of feldspar microlites. The findings of this study hold the promise of a better understanding of volcanic timescales during magma ascent in the conduit, as well as the possibility of extending our model to more complicated scenarios with changing pressure and temperature.

Keywords: Nucleation delay; Ascent rate; Crystallization; Decompression; Magmatic timescales

Domains: Sciences of the Universe [physics]; Sciences of the Universe [physics]; Earth Sciences

Monika K. Rusiecka, Caroline Martel. Nucleation delay in water-saturated rhyolite during decompression in shallow volcanic systems and its implications for ascent dynamics. Bulletin of Volcanology, 2022, 84, 326, p. 56-76. ⟨10.1007/s00445-022-01569-1⟩. ⟨insu-03691304⟩