The mafic Curacautín ignimbrite of Llaima volcano, Chile

Mafic volcanism accounts for 80% of magmas erupted on Earth. Although the majority these eruptions are effusive to Strombolian and fountain-fed, large explosive mafic do occur. This work uses deposits pyroclast textures from 12.6 ka Curacautín ignimbrite eruption Llaima volcano constrain conditions that drove this extrapolate findings provide insights into promote large-volume, elsewhere. The (Ci) consists four massive coarse ash lapilli tuff flow units; Unit 1 is at least 30 m thick in proximal exposures, Units 2–4 range 4 thick. New 14C dates field observations suggest Ci result a single eruptive episode ~12.6 ka. A lack fall presence abundant clast agglutination suggests was boil over event. We estimate tephra volume be between 6 9 km3 (equivalent 3.5–4.5 DRE), which less than previous estimates. Even with our lower estimate, still larger Masaya Triple Layer, Pucón ignimbrite, Tarawera 1886, Etna 122 BCE eruptions. Average vesicularities pyroclasts 43 71%, all but one exposure have ≤56%. phenocryst content ≤1–3%, plagioclase microlite crystallinities 29 44%, volumetric number densities 8.21 × 106 1.84 107 mm−3. Such high disequilibrium resulting rapid magma ascent decompression. interpret combination increased viscosity due crystallization microlites caused gases remain coupled magma. This, textures, explosivity driven by brittle fragmentation. Assuming mass rates exceeded 2.0 10 8 kg s − produce complete column collapse, we an duration ~15–17 h. study further supports interpretation extensive nucleation can lead