Most explosive, silicic volcanoes spend thousands of years in repose between eruptive events. The timing of the switch from repose to eruption is key to interpreting monitoring signals and improving the safety of people living close to active volcanoes. We addressed this question using a novel technique based on lithium isotopic (δ⁷Li) and elemental concentration profiles within plagioclase crystals from the Mesa Falls Tuff of the Yellowstone volcanic system (Idaho and Wyoming, USA), constraining volatile degassing to occur on minimum time scales of tens of minutes prior to eruption. During this ephemeral time, Li abundances drop by a factor of four to 10 from crystal cores to rims, accompanied by an increase in δ⁷Li of as much as 10‰, reflecting diffusion-driven equilibration between plagioclase cores and outgassed, Li-poor melt. New times scales obtained in this study show the potential for rapid syneruptive changes in the volatile inventory of magmas.

中文翻译：

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锂同位素量化硅质岩浆中协同挥发损失的时标

大多数爆发性的硅质火山在爆发事件之间要花费数千年的时间。从安息过渡到喷发的时机是解释监测信号并提高居住在活火山附近人员安全的关键。我们解决使用一种新的技术这个问题基于锂同位素（δ ⁷ Li）和从黄石火山系统的梅萨瀑布凝灰岩（爱达荷州和怀俄明州，USA）斜长石晶体内的元素浓度分布，约束挥发性脱气最小时间发生爆发前数十分钟的鳞片。在这个短暂的时间，李丰度从晶核到轮缘掉落通过的四倍到10，在δ同时增加⁷Li高达10‰，反映了斜长石核与脱气的，贫锂熔体之间的扩散驱动平衡。在这项研究中获得的新的时间尺度显示了岩浆挥发性库存中快速协同变化的潜力。