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

合作研究：熔体海湾与岩浆上升的关系有多忠实？

• 批准号: 2015424
• 负责人: Benjamin Andrews
• 金额: $ 2.36万
• 依托单位: Smithsonian Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2015424&HistoricalAwards=false
• 关键词: Collaborative; Research; How; faithfully; melt

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.

爆炸性喷发会造成广泛的社会影响。火山爆发的爆炸性部分取决于岩浆在管道中上升的速度。直接测量岩浆上升具有挑战性，因为它发生在地下和危险的环境中。被冻结的岩浆被困在晶体中的小气泡，称为海湾，可能以化学扩散梯度的形式保存了上升速度的记录，科学家可以将其用作一种岩浆速度计。这种海湾技术已越来越多地用于了解古代火山爆发的动力学。随着这种速度计技术越来越受欢迎，验证其准确性很重要。在这里，一系列的实验室实验使用了处于岩浆温度和压力下的真实的岩浆，将在受控条件下重现岩浆上升，以测试海湾如何记录这一过程。仔细比较受控实验室条件和实验海湾中的扩散梯度，将澄清“如果”和“如何”？海湾忠实地记录了岩浆的上升。研究生和本科生将在纽约市立大学和贝勒大学接受研究方法的培训。此外，还将在国家自然历史博物馆和纽约虚拟火山观测站以“科学家在场”会议和关于岩浆上升的短格式教育录像的形式开展公众宣传活动。 量化岩浆在火山管道中上升的速度对于了解喷发的时间、规模和行为至关重要。被认为是保存在海湾内的熔体淬火袋保持这样的速率作为扩散平衡控制的成分梯度。过去使用海湾来确定岩浆上升速率的研究使用了一些精心挑选的样本，并做出了合理但未经检验的假设，涉及扩散和减压途径。海湾geoseedometry的关键假设，必须通过实验验证，才能有信心地用于推进火山喷发动力学的理解。在这里，海湾geoseedometry的理论基础将系统地测试对集中套件的天然样品和一系列的减压实验，使用天然和合成海湾。重要的测试包括（1）发现一个单一的海湾如何代表一批岩浆，以及（2）观察到的扩散轮廓是否与实验条件和关键假设预测的相匹配。如果实验海湾被证明是强大的，那么海湾geoseedometry将成为一个有价值的工具，了解火山喷发期间的火山管道的条件。如果实验扩散曲线与实验条件预测的不匹配，那么实验将为探索海湾记录的复杂性提供一个经验框架。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。