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.

Mots clés: Nucleation delay; Ascent rate; Crystallization; Decompression; Magmatic timescales

Domaines: Planète et Univers [physics]; Sciences de la Terre

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⟩