This is a repository copy of A cascade of magmatic events during the assembly and eruption of a super-sized magma body.

Understanding the origins of the mantle melts that drive voluminous silicic volcanism is challenging because primitive magmas are generally trapped at depth. The central Taupō Volcanic Zone (TVZ; New Zealand) hosts an extraordinarily productive region of rhyolitic caldera volcanism. Accompanying and interspersed with the rhyolitic products, there are traces of basalt to andesite preserved as enclaves or pyroclasts in caldera eruption products and occurring as small monogenetic eruptive centers between calderas. These mafic materials contain MgO-rich olivines (Fo79–86) that host melt inclusions capturing the most primitive basaltic melts fueling the central TVZ. Olivine-hosted melt inclusion compositions associated with the caldera volcanoes (intracaldera samples) contrast with those from the nearby, mafic intercaldera monogenetic centers. Intracaldera melt inclusions from the modern caldera volcanoes of Taupō and Okataina have lower abundances of incompatible elements, reflecting distinct mantle melts. There is a direct link showing that caldera-related silicic volcanism is fueled by basaltic magmas that have resulted from higher degrees of partial melting of a more depleted mantle source, along with distinct subduction signatures. The locations and vigor of Taupō and Okataina are fundamentally related to the degree of melting and flux of basalt from the mantle, and intercaldera mafic eruptive products are thus not representative of the feeder magmas for the caldera volcanoes. Inherited olivines and their melt inclusions provide a unique “window” into the mantle dynamics that drive the active TVZ silicic magmatic systems and may present a useful approach at other volcanoes that show evidence for mafic recharge.

<div><strong><strong>Large-volume rhyolitic eruptions are characteristically crystal-poor yet are thought to originate from crystal rich magma mush bodies. This contradiction is explained by the interstitial melt being extracted prior to the eruption, generating large volumes of crystal-poor magmas. The timescale for melt extraction is inversely correlated to the permeability of the mush, defined by the shape of the crystals. Yet, existing approaches for estimating the crystal framework permeability do not account for crystal shape. Here, we represent magma mush by using numerically generated packs of hard cuboids with a range of aspect ratios and at their maximally dense random packing. We use lattice-Boltzmann simulations to constrain the permeability of the cuboid packs, showing that crystal shape exerts a first-order control on both the melt fraction at maximum packing, and on the constitutive relationship between permeability and melt </strong>fraction. Using percolation theory and a validation dataset, we develop a predictive scaling framework to compute permeability for mush comprised of crystals that can be approximated by cuboids, valid at melt fractions down to, and including the random maximum packing of crystals. We show that for packs of prolate cuboids, the melt extraction timescale can be reduced by almost two orders of magnitude relative to a pack of oblate cuboids, implying that rejuvenation timescales leading to eruption</strong> <strong>could be much shorter than previously predicted, using our novel permeability model that is sensitive to crystal shape.</strong></div>