Abstract : 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.
https://hal-insu.archives-ouvertes.fr/insu-03691304 Contributor : Nathalie POTHIERConnect in order to contact the contributor Submitted on : Thursday, June 16, 2022 - 9:57:03 AM Last modification on : Thursday, June 16, 2022 - 9:57:05 AM
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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⟩