根据岩浆对冰消作用的响应，冰岛之下的熔体上升速率
Rate of Melt Ascent beneath Iceland from the Magmatic Response to Deglaciation
摘要：
对冰岛最后一次冰消期和火山活动激增之间的时间差的观测限制了平均融化上升速度为$\geq50$ $\mathrm{m/yr}$。虽然现有的理论工作已经解释了为什么在喷发率激增增加$5$ - $30$倍，从稳定状态的利率在最后一次冰消期，他们不能解释大的变化，稀土元素（REE）的浓度在冰岛熔岩。熔岩爆发在最后一次冰消期耗尽稀土元素的$70\%$，而现有的模型，假设瞬时熔体输送，只能产生最多$20\%$耗尽。在这里，我们开发了一个有限的熔体上升速度的数值模型，并表明稀土元素的变化强烈依赖于熔体上升速度。当平均熔体上升速度为$100$ $\mathrm{m/yr}$时，用本模型计算的$\mathrm{La}$的变化与观测值相当。相反，当熔体上升速度为$1,000$ $\mathrm{m/yr}$或以上时，$\mathrm{La}$的模型变化变得明显低于观察到的，这解释了为什么先前的瞬时熔体输送模型没有再现大的变化。我们提供的第一个模型，考虑到冰川消退的火山作用的历时性反应。我们通过比较我们的模型计算的相对体积不同的喷发类型（冰下，冰末和冰后期）和火山爆发的时间在不同的火山区，冰岛的平均融化上升速度在末次冰消期的观测结果很可能是$\sim100$ $\mathrm{m/yr}$。
英文摘要：
Observations of the time lag between the last deglaciation and a surge in volcanic activity in Iceland constrain the average melt ascent velocity to be $\geq50$ $\mathrm{m/yr}$. Although existing theoretical work has explained why the surge in eruption rates increased $5$-$30$ fold from the steady-state rates during the last deglaciation, they cannot account for large variations of Rare Earth Element (REE) concentrations in the Icelandic lavas. Lavas erupted during the last deglaciation are depleted in REEs by up to $70\%$; whereas, existing models, which assume instantaneous melt transport, can only produce at most $20\%$ depletion. Here, we develop a numerical model with finite melt ascent velocity and show that the variations of REEs are strongly dependent on the melt ascent velocity. When the average melt ascent velocity is $100$ $\mathrm{m/yr}$, the variation of $\mathrm{La}$ calculated by our model is comparable to that of the observations. In contrast, when the melt ascent velocity is $1,000$ $\mathrm{m/yr}$ or above, the model variation of $\mathrm{La}$ becomes significantly lower than observed, which explains why previous models with instantaneous melt transport did not reproduce the large variations. We provide the first model that takes account of the diachronous response of volcanism to deglaciation. We show by comparing our model calculations of the relative volumes of different eruption types (subglacial, finiglacial and postglacial) and the timing of the bursts in volcanic eruptions with the observations across different volcanic zones that the Icelandic average melt ascent velocity during the last deglaciation is likely to be $\sim100$ $\mathrm{m/yr}$.
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