Black, Benjamin A. and Andrews, Benjamin J. 2020. "Petrologic imaging of the architecture of magma reservoirs feeding caldera-forming eruptions." Earth and Planetary Science Letters 552:116572-116572. https://doi.org/10.1016/j.epsl.2020.116572
Caldera 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 similar to 10(0 )km(3) to similar to 10(3) km(3) 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. (C) 2020 Elsevier B.V. All rights reserved.