Magma decompression rate has profound impacts on volcanic eruption style as it determines the time available for most kinetic processes (e.g., volatile exsolution, crystal nucleation and growth) that influence the explosive‐effusive eruption transition. Thus, accurately quantifying decompression rate is a critical goal for understanding volcanic eruption dynamics. A recently developed technique uses crystal‐hosted pockets of melt that remain open to the host magma (melt embayments) to calculate an average decompression rate. Diffusion of volatile elements (e.g., H₂O, CO₂) out of the embayment during decompression creates “frozen” concentration gradients upon quenching that can be modeled to calculate the time needed to create the gradients. This geospeedometer is increasingly used, but inherent assumptions associated with the modeling and their impact on calculated decompression rates are poorly quantified. Therefore, we have conducted a numerical investigation to assess the impact of three common model simplifications pertaining to rhyolitic magmas: 1D diffusion models, equilibrium degassing, and isothermal decompression. We find that the greatest deviation between imposed and calculated decompression rates occur when 1D models are applied to “necked” embayments that have a constriction where the embayment joins with the far field melt. Simplifying to equilibrium degassing can also introduce modeling errors when disequilibrium conditions exist, though the prevalence of one or the other condition in nature is currently under debate. Assuming isothermal conditions introduces little error into modeled timescales. All of our modeling results are summarized into a list of best practices to minimize error in modeled timescales due to modeling assumptions.

中文翻译：

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使用晶体寄主熔体中的挥发性元素浓度分布来估算岩浆减压速率：假设和继承的错误

岩浆减压速率对火山喷发方式有深远的影响，因为它决定了影响爆炸性喷发过渡的大多数动力学过程（例如，挥发物释放，晶体成核和生长）可用的时间。因此，准确量化减压速率是了解火山喷发动力学的关键目标。一项最新开发的技术使用晶体承载的熔体袋，这些熔体对主体岩浆保持开放（熔体沉积物），以计算平均减压速率。挥发性元素（例如H ₂ O，CO _2）的扩散）在减压期间从隔间出来时会在淬火时创建“冻结”浓度梯度，可以对其进行建模以计算出创建梯度所需的时间。越来越多地使用这种地球速度计，但是与建模相关的固有假设及其对计算的减压率的影响却很难量化。因此，我们进行了一项数值研究，以评估与流纹岩浆有关的三种常见模型简化的影响：一维扩散模型，平衡脱气和等温减压。我们发现，当将一维模型应用于“颈缩”式嵌入物时，最大压缩量与计算出的减压率之间会出现最大偏差，该收缩物会在收缩物与远场融化相结合的地方产生收缩。当存在不平衡条件时，简化为平衡脱气也会引入建模误差，尽管目前正在讨论自然界中一种或另一种条件的普遍性。假设等温条件在建模时标中引入的误差很小。我们所有的建模结果均汇总为一系列最佳实践，以最大程度地减少由于建模假设而在建模时标中产生的误差。