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.

爆炸性爆发会引起广泛的社会影响。火山喷发的爆炸性部分通过导管中的岩浆上升的速度来控制。直接测量岩浆上升是挑战的，因为它发生在地下和危险环境中。被困在晶体中的冰冻岩浆的小泡泡（称为胚胎）可以保留科学家可以用作岩浆速度表的化学扩散梯度的上升速率记录。这种嵌入技术越来越多地用于了解古代火山喷发的动态。随着这种速度计技术的越来越受欢迎，验证其准确性很重要。在这里，在岩浆温度和压力下使用真实岩浆进行的一系列实验室实验将在受控条件下重新创建岩浆上升，以测试胚胎记录该过程的效果。仔细比较实验室条件和实验胚胎中的扩散梯度将澄清“ if”和“ how？”胚胎忠实地记录了岩浆上升。研究生和本科生将接受CUNY和Baylor的研究方法的培训。此外，公共宣传将在国家自然历史博物馆和纽约虚拟火山天文台上以“科学家IS-IN”会议的形式和有关岩浆上升的简短教育视频的形式进行。量化火山导管中岩浆上升的速度对于理解喷发的时机，幅度和行为至关重要。认为保存在胚胎中的熔融熔体被认为可以保留诸如由不同等效控制的复合梯度的速率。过去使用胚胎来确定岩浆上升速率的研究使用了一些精心选择的样品，并做出了涉及扩散和减压途径的合理但未测试的假设。在可以自信地使用对火山喷发动力学的理解之前，必须对其进行实验验证的基础地理呼吸法基础的关键假设。在这里，将针对自然样品的聚焦套件进行系统的测试，并使用天然和合成胚胎进行一系列的减压实验，对体进行的地理轴测测定法的理论基础进行系统的测试。重要的测试包括（1）发现单个胚胎代表一批岩浆的很好，（2）观察到的扩散曲线是否与从实验条件和关键假设中预测的扩散曲线相匹配。如果证明实验性胚胎是健壮的，则胚胎地理测定法将成为理解喷发过程中火山导管条件的有价值工具。如果证明实验性扩散曲线与实验条件所预测的剖面不匹配，那么实验将为探索胚胎记录的复杂性提供一个经验框架。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子和更广泛的影响审查标准来通过评估来诚实地认为通过评估来诚实地支持。