Collaborative Research: How faithfully are melt embayments wedded to magma ascent?

爆炸性喷发可能造成广泛的社会影响。火山喷发的爆炸性在一定程度上取决于岩浆在管道中上升的速度。直接测量岩浆上升是具有挑战性的，因为它发生在地下和危险的环境中。被困在晶体中的冻结岩浆小气泡，被称为洞穴，可能会以化学扩散梯度的形式保存上升速度的记录，科学家可以将其用作一种岩浆速度计。这种埋藏技术越来越多地被用来了解古代火山喷发的动力学。随着这种速度计技术越来越受欢迎，验证其准确性非常重要。在这里，利用真实岩浆在岩浆温度和压力下进行的一系列实验室实验将在受控条件下重现岩浆上升，以测试海湾记录这一过程的程度。在受控实验室条件和实验海湾扩散梯度之间的仔细比较将澄清“如果”和“如何？”洞穴忠实地记录了岩浆的上升。研究生和本科生将在纽约州立大学和贝勒接受研究方法培训。此外，还将在国家自然历史博物馆和纽约虚拟火山观测站开展公众宣传活动，形式为“科学家在”会议和关于岩浆上升的短格式教育视频。量化火山导管中岩浆上升的速度对于了解火山喷发的时间、规模和行为至关重要。保存在海湾内的淬火熔体被认为保留了由扩散平衡控制的成分梯度等速率。过去使用海湾来确定岩浆上升速率的研究使用了几个精心挑选的样品，并做出了合理但未经检验的假设，涉及扩散和减压途径。在可以自信地用来推进对火山喷发动力学的理解之前，必须通过实验验证作为海湾地质测速基础的关键假设。在这里，将针对自然样品的聚焦套件以及使用自然和合成海湾进行的一系列减压实验来系统地检验海湾地质测速的理论基础。重要的测试包括(1)发现单个海湾代表一批岩浆的程度，以及(2)观察到的扩散剖面是否与实验条件和关键假设所预测的相符。如果实验证明海湾是坚固的，那么海湾地质测速将成为了解火山喷发期间管道条件的有价值的工具。相反，如果实验扩散曲线与实验条件预测的结果不匹配，那么实验将为探索入侵者记录的复杂性提供一个经验框架。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Explosive eruptions can cause wide-ranging societal impacts. The explosivity of a volcanic eruption is controlled in part by how fast magma rises in the conduit. Directly measuring magma ascent is challenging because it takes place underground and in a dangerous environment. Small blebs of frozen magma trapped in crystals, called embayments, may preserve a record of ascent rate in the form of chemical diffusion gradients that scientists can apply as a kind of magma speedometer. This embayment technique has been increasingly used to understand the dynamics of ancient volcanic eruptions. As this speedometer technique grows in popularity, validating its accuracy is important. Here, a series of laboratory experiments conducted using real magma at magmatic temperatures and pressures will recreate magma ascent under controlled conditions to test how well embayments record this process. Careful comparison between the controlled lab conditions and the diffusion gradients in the experimental embayments will clarify “if” and “how?” embayments faithfully record magmatic ascent. Graduate and undergraduate students will be trained in research methods at CUNY and Baylor. In addition, public outreach will be performed at the National Museum of Natural History and the NY Virtual Volcano Observatory in the form of “Scientist-is-In” sessions and short-format educational videos on magma ascent. Quantifying the rate of magma ascent in the volcanic conduit is critical to understanding the timing, magnitude, and behavior of eruptions. Quenched pockets of melt preserved within embayments are thought to preserve such rates as compositional gradients controlled by diffusive equilibration. Past studies using embayments to determine magma ascent rates have used a few, carefully selected samples and have made reasonable, but untested, assumptions involving diffusion and decompression pathway. The key assumptions underlying embayment geospeedometry must be experimentally validated before it can be confidently used to advance the understanding of volcanic eruption dynamics. Here, the theoretical basis for embayment geospeedometry will be systematically tested against focused suites of natural samples and a series of decompression experiments using natural and synthetic embayments. Important tests include (1) discovering how well a single embayment represents a batch of magma, and (2) whether observed diffusion profiles match those predicted from experimental conditions and key assumptions. If the experimental embayments are shown to be robust, then embayment geospeedometry will become a valuable tool for understanding the conditions in volcanic conduits during eruption. If experimental diffusion profiles are instead shown to not match those predicted by experimental conditions then the experiments will provide an empirical framework for exploring the complexities recorded by embayments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.