Using Chemical Affinities to Understand Disequilibrium Textures of Plagioclase Preserved in Magmatic Systems

Abstract

Magmatic systems are susceptible to changes in their equilibrium state through mass and energy exchange.The implication of open-system behavior manifests in changes in rheologic properties of the magma, affecting magma ascent and eruption style (Cassidy et al., 2018;Métrich et al., 2010;Ruprecht & Bachmann, 2010). The perturbation away from chemical equilibrium during the course of magma evolution is most pronounced during syn-eruptive ascent, where rapid changes in dissolved volatiles have large effects on the equilibrium phase assemblage (

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

“…2008 eruption of Chaitén (Northern Patagonia, Chile). There has been discussion as to the reason of the lack of microlites in the products of this eruption (Andrews and Befus 2020,Huggins et al 2021). Andrews and Befus (2020), who in presenting their Supersaturation Nucleation and Growth of Plagioclase (SNGPlag) numerical model, suggested that the reason their model was unable to reproduce the crystal poor textures of the 2008 Chaiten eruption was the fact that they did not include nucleation delay in their calculations Castro and Dingwell (2009).…”