Journal ArticlePetrologic imaging of the architecture of magma reservoirs feeding caldera-forming eruptionsBlack, Benjamin A; Andrews, BenjaminnullCaldera footprints and erupted magma volumes provide a unique constraint on vertical dimensions of upper crustal magma reservoirs that feed explosive silicic eruptions. Here we define a Vertical Separation (VS) ratio in which we compare the geometric vertical extent with the range of depths indicated petrologically by melt inclusion water and CO2 saturation pressures for fifteen caldera-forming eruptions spanning ∼10^0 km3 to ∼10^3 km3 in volume. We supplement melt inclusion saturation pressures with rhyolite-MELTS barometry and plagioclase-melt hygrometry to generate a petrologic image of magma reservoir architecture. We find that pre-eruptive upper crustal magma reservoirs range from contiguous bodies (where petrologic and geometric estimates match closely) to vertically dispersed structures. Vertically dispersed pre-eruptive reservoirs are more common among intermediate-volume eruptions than among the smallest and largest caldera-forming eruptions. We infer that the architecture of magma reservoirs tracks the thermomechanical evolution of large volcanic systems.2020-12-1510290474Earth and planetary science letters5520012-821Xhttps://doi.org/10.1130/abs/2020AM-3577182015322National Science Foundation