Fig. 3: Liquid immiscibility in El Laco andesite.
From: Genetic model of the El Laco magnetite-apatite deposits by extrusion of iron-rich melt
Back-scattered electron images of plagioclase-hosted (plg) melt inclusions from ore-hosting andesites; a Fe-rich globules in Si-rich matrix; b higher magnification image shows high-SiO2 dacite glass matrix with some clinopyroxene micro-phenocrysts (micro-cpx), and Fe-rich globules comprised of Fe-clinopyroxene (Fe-cpx) with some nanocrystalline magnetite (nano-mt); plagioclase shows pillar structures indicative of melt unmixing during crystallisation19. Modelling of closed-system isobaric cooling in alphaMELTS shown at 50 °C intervals from 1050 °C (darker) to 850 °C (lighter) in (c) predict Si-rich melt (blue) similar to analyses of high-SiO2 dacite glass (green, error bars ± 1 standard deviation), Fe-rich melt (red)16 on mixing line between analyses of Fe-cpx (pink, error bars ± 1 standard deviation) and magnetite (amber) from inclusions15, with reconstructed Fe-cpx-mt globules from 80% Fe-cpx + 20% mt shown as asterisk; approximate miscibility gap (dashed) according to experimental results18 (grey symbols). Modelled phase fractions (d) show similar crystal types and abundances to observations and experiments.
