The effect of nonlinear decompression history on H2O/CO2 vesiculation in rhyolitic magmas
The effect of nonlinear decompression history on H2O/CO2 vesiculation in rhyolitic magmas
复制标题
非线性减压历史对流纹质岩浆中H2O/CO2泡化的影响
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
C. Huber
中科院分区：
文献类型：
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作者：
Yanqing Su;C. Huber
岩浆上升速率是控制火山喷发方式、火山碎屑扩散和火山大气影响的关键参数之一。研究火山喷发过程中岩浆上升速率的方法很多，但大多数都依赖于平衡态热力学。结合混合H2O-CO2溶解度模型与正常流纹岩熔体的H2O和CO2的扩散系数，我们模拟了流纹岩喷发中涉及非线性减压速率的H2O和CO2的动力学。我们的研究重点是总岩浆上升时间的影响，减压路径的非线性，以及不同的初始CO2/H2O含量的影响posteruptive H2O和CO2浓度分布周围的气泡熔体。我们的研究结果表明，在大多数情况下，挥发性扩散配置文件不约束一个独特的解决方案，在喷发过程中的岩浆减压速率，但相反，提供了一个家庭的减压路径与上升时间和非线性之间的一个明确的权衡。我们的分析的一个重要结果是，一个恒定的减压速率（平均值）的共同假设往往低估了实际的岩浆上升时间。
Magma ascent rate is one of the key parameters that control volcanic eruption style, tephra dispersion, and volcanic atmospheric impact. Many methods have been employed to investigate the magma ascent rate in volcanic eruptions, and most rely on equilibrium thermodynamics. Combining the mixed H2O‐CO2 solubility model with the diffusivities of both H2O and CO2 for normal rhyolitic melt, we model the kinetics of H2O and CO2 in rhyolitic eruptions that involve nonlinear decompression rates. Our study focuses on the effects of the total magma ascent time, the nonlinearity of decompression paths, and the influence of different initial CO2/H2O content on the posteruptive H2O and CO2 concentration profiles around bubbles within the melt. Our results show that, under most circumstances, volatile diffusion profiles do not constrain a unique solution for the decompression rate of magmas during an eruption, but, instead, provide a family of decompression paths with a well‐defined trade‐off between ascent time and nonlinearity. An important consequence of our analysis is that the common assumption of a constant decompression rate (averaged value) tends to underestimate the actual magma ascent time.