Insights for crystal mush storage utilizing mafic enclaves from the 2011-12 Cordón Caulle eruption.

Two distinct types of rare crystal-rich mafic enclaves have been identified in the rhyolite lava flow from the 2011-12 Cordón Caulle eruption (Southern Andean Volcanic Zone, SVZ). The majority of mafic enclaves are coarsely crystalline with interlocking olivine-clinopyroxene-plagioclase textures and irregular shaped vesicles filling the crystal framework. These enclaves are interpreted as pieces of crystal-rich magma mush underlying a crystal-poor rhyolitic magma body that has fed recent silicic eruptions at Cordón Caulle.

Out-of-sequence skeletal growth causing oscillatory zoning in arc olivines.

Primitive olivines from the monogenetic cones Los Hornitos, Central-South Andes, preserve dendritic, skeletal, and polyhedral growth textures. Consecutive stages of textural maturation occur along compositional gradients where high Fo-Ni cores of polyhedral olivines (Fo, Ni ~3500 ppm) contrast with the composition of dendritic olivines (Fo < 91.5, Ni < 3000 ppm), indicating sequential nucleation.

Feeding andesitic eruptions with a high-speed connection from the mantle.

Convergent margin volcanism is ultimately fed by magmas generated in the mantle, but the connection between the mantle and the eruption at the surface is typically obscured by cooling, crystallization and magma mixing within the crust. Geophysical techniques are also not very effective in the lower and middle crust, where seismic events are rare and resolution is generally poor. It has thus been unclear how fast mantle-derived magmas transit the crust and recharge crustal magma chambers.