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: 2015322
• 负责人: Benjamin Black
• 金额: $ 15.72万
• 依托单位: CUNY City College
• 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 2022-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2015322&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。火山喷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，因为它发生在地下且环境危险。被困在晶体中的冰冻岩浆小气泡（称为海湾）可以以化学扩散梯度的形式保存上升速率的记录，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喷发的动态。随着这种速度计技术的日益普及，验证其准确性非常重要。在这里，使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效果。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培训。此外，国家自然历史博物馆和纽约虚拟火山观测站还将以“科学家就在”会议和有关岩浆上升的简短教育视频的形式进行公众宣传。 量化火山管道中岩浆上升的速度对于了解喷发的时间、强度和行为至关重要。人们认为，在海湾内保存的淬火熔体袋可以保持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一些精心挑选的样本，并做出了涉及扩散和减压路径的合理但未经测试的假设。海湾地球速度测量的关键假设必须经过实验验证，然后才能放心地用于增进对火山喷发动力学的理解。在这里，海湾地球速度测量的理论基础将针对自然样本的集中套件以及使用天然和合成海湾的一系列减压实验进行系统测试。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预测的相符。如果实验海湾被证明是稳健的，那么海湾地球速度测量将成为了解火山喷发期间火山管道状况的宝贵工具。如果实验扩散概况与实验条件预测的不相符，那么实验将为探索海湾记录的复杂性提供一个实证框架。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Petrologic imaging of the architecture of magma reservoirs feeding caldera-forming eruptions

火山口形成喷发的岩浆库结构的岩石学成像

• DOI: 10.1130/abs/2020am-357718
• 发表时间: 2020
• 期刊: Earth and planetary science letters
• 影响因子: 5.3
• 作者: Black, Benjamin A;Andrews, Benjamin
• 通讯作者: Andrews, Benjamin

Global climate disruption and regional climate shelters after the Toba supereruption

• DOI: 10.1073/pnas.2013046118
• 发表时间: 2021-07-20
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Black, Benjamin A.;Lamarque, Jean-Francois;Bardeen, Charles G.
• 通讯作者: Bardeen, Charles G.

Reckoning with the Rocky Relationship Between Eruption Size and Climate Response: Toward a Volcano-Climate Index

• DOI: 10.1146/annurev-earth-080921-052816
• 发表时间: 2022-05
• 期刊: Annual Review of Earth and Planetary Sciences
• 影响因子: 14.9
• 作者: A. Schmidt;B. Black