Abstract 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 ∼100 km3 to ∼103 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.

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火山口形成喷发的岩浆储层结构的岩石学成像

摘要 火山口足迹和喷发的岩浆体积对上地壳岩浆储层的垂直尺寸提供了独特的约束，这些岩浆储层为硅质爆炸性喷发提供了养料。在这里，我们定义了一个垂直分离 (VS) 比率，在该比率中，我们将几何垂直范围与由熔体包裹体水和 CO2 饱和压力从岩石学上指示的深度范围进行比较，这些火山喷发的体积跨度约为 100 平方公里至 103 平方公里。我们用流纹岩-熔体气压计和斜长石-熔体湿度计补充熔体包裹体饱和压力，以生成岩浆储层结构的岩石学图像。我们发现喷发前上地壳岩浆储层的范围从毗连体（其中岩石学和几何估计密切匹配）到垂直分散的结构。垂直分散的喷发前水库在中等体积的喷发中比在最小和最大的火山口形成喷发中更常见。我们推断岩浆储层的结构跟踪了大型火山系统的热机械演化。