Large silicic eruptions result from rapid evacuation of large, upper crustal reservoirs of silicic magmas. These silicic magmas are thought to be replenished by melt extracted from underlying crystal‐rich source mushes, but the timescales and mechanisms of such melt extraction are unclear. Geochemical observations suggest that the replenishing melt is often more primitive than the eruptives and must thus cool and crystallize to generate the highly silicic magmas that eventually lead to large eruptions. Motivated by these observations, we use thermal models to explore the replenishment conditions capable of building an eruptible silicic reservoir to generate a large eruption. Results show that the minimum melt replenishment rate required for a silicic reservoir to start growing increases with the effective thermal diffusivity of the overlying crust and decreases with the depth of the reservoir. For an eruptible reservoir at 6 km depth to grow, the initial replenishment rate needs to be greater than 2 × 10⁻⁹ m/s. High replenishment rates are required to provide enough advected heat to counterbalance rapid heat loss and consequent freezing that would prevent the eruptible reservoir from growing. However, these high initial replenishment rates must then subside over time for the eruptible reservoir to cool, crystallize, and evolve to highly silicic melts. Thermal histories of some natural systems suggest assembly of large eruptible reservoirs in <20 kyr. The rapid replenishment followed by its decay suggests that replenishment was triggered by a pronounced but ephemeral increase in the porosity and permeability of the underlying crystal‐rich source mush, allowing for rapid melt expulsion. We speculate that this perturbation may be driven by the sudden incursion of deep‐seated, hotter magmas into the base of the crystal‐rich source mush.

中文翻译：

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大型硅爆发，间歇性补给和跨壳岩浆系统

大型硅质岩浆的大型上地壳储层快速撤离导致了大型的硅质喷发。这些硅质岩浆被认为是通过从潜在的富含晶体的源性麝香中提取熔体来补充的，但这种熔体提取的时间尺度和机理尚不清楚。地球化学观测表明，补充性熔体通常比火山喷发物更为原始，因此必须冷却和结晶以生成高度硅化的岩浆，最终导致大型火山喷发。受这些观测结果的激励，我们使用热模型来探索能够建立可爆发的硅质油藏以产生大喷发的补给条件。结果表明，硅质储层开始生长所需的最小熔体补充速率随上覆地壳的有效热扩散率而增加，并随储层深度而降低。为了使6公里深度处的喷发性水库能够生长，初始补给率需要大于2×10⁻⁹ 多发性硬化症。需要较高的补给率​​以提供足够的对流热量，以抵消快速的热损失和随之而来的冻结，这将阻止可爆发的储层生长。但是，随着时间的流逝，这些高的初始补给率必须逐渐降低，以使可喷出的储层冷却，结晶并演变成高硅质熔体。一些自然系统的热史表明，在小于20年的时间里组装了大型可喷出油藏。快速补给及其随后的衰减表明，补给是由下面的富含晶体的源岩浆的孔隙度和渗透率的明显但短暂的增加触发的，从而可以快速排出熔体。我们推测这种扰动可能是由于深层，较热的岩浆突然侵入富含晶体的源岩浆的基底而引起的。