Investigating the volatile evolution and decompression rate of high-intensity basaltic eruptions

对高爆炸性火山喷发的驱动因素的了解主要集中在长硅（高硅熔体）喷发上。然而，尽管基性火山活动是地球上最常见的火山活动类型，它们也可能引发毁灭性的社会和环境影响，但类似爆炸性强度的基性火山（镁含量较低的熔体）爆发尚未得到研究。该项目旨在通过重建熔体包裹体的化学演化和挥发性收支来提高对基性火山作用的理解，熔体包裹体是在晶体生长过程中被捕获的小液滴，保存了地质记录中最具爆炸性的基性火山喷发的历史。这项研究将提供关于岩浆上升到爆发的时间尺度的见解，这可以用于通知喷发响应工作和预测。研究小组将与美国地质调查局夏威夷火山观测站（HVO-USGS）合作，在全球火山监测和风险评估机构之间传播知识。这项工作还将通过支持活火山研究中心（CSAV）夏季课程的一个模块，扩大地球化学技术在火山监测和反应方面的全球应用。该项目将支持研究生和本科生在康奈尔大学和HVO接受不同微分析技术的培训，并应用这些技术来了解火山喷发。这个项目的成果将被纳入康奈尔大学的地球材料和火山学课程。最后，该项目将通过与康奈尔大学、HVO-USGS、曼彻斯特大学、ldeo -哥伦比亚大学、奥克兰大学、加州理工学院和锡拉丘兹大学建立合作关系，加强研究和教育的基础设施。高强度火山爆发（亚普林尼期、普林尼期和超普林尼期，火山爆发指数为6+）造成全球环境影响，并具有巨大的破坏性社会影响潜力。在这些喷发中，基性喷发是研究最少的，是一个迫切需要进一步研究的关键端元。特别令人感兴趣的是它们的岩浆减压率（dP/dt）的测定，因为这个参数在确定玄武岩岩浆喷发动力学中的火山作用类型方面起着至关重要的作用。本项目将研究玄武岩普林尼期至次普林尼期喷发的挥发演化和减压。这些喷发代表了玄武岩火山活动中最具灾难性和最不为人所知的末端成员。重建它们的喷发历史将解决以下问题：1)玄武岩普林尼火山喷发的喷发前条件和脱气记录是什么？为了准确地限制岩浆条件，喷发前和喷发期间挥发性饱和度和脱气的演变，以及减压途径，研究小组将使用橄榄石为主的MIs。2)玄武岩普林尼火山喷发的减压率是多少？对所提出的喷发案例研究的岩浆减压率估计需要通过数值模型、实验和晶体结构来改进或间接限制。这项工作的目的是利用两种基于时间依赖性化学反应的岩石学工具来补充挥发物演化史：挥发物在橄榄石基质上的扩散和橄榄石晶体中H+的浓度梯度。3)高强度基性火山喷发减压率与喷发震级是否存在相关性？目前的资料表明，低度和轻度爆炸性玄武岩喷发减压率与喷发震级呈明显的正相关。然而，这些数据并不适用于更大规模的喷发。该项目将通过新的减压率研究和文献数据来回答这个问题。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Knowledge of the driving factors in generating highly explosive volcanic eruptions has been mostly focused on felsic (evolved melts high in silica) eruptions. Nevertheless, mafic (less evolved melts high in magnesium) eruptions of similar explosivity intensity have yet to be studied, even though mafic volcanism is the most common type of volcanic activity on Earth, and they could also trigger devastating societal and environmental impacts. This project aims to improve understanding of mafic volcanism by reconstructing the chemical evolution and volatile budgets from melt inclusions, small droplets of melt trapped during crystal growth that preserved the history of the most explosive mafic eruptions in the geologic record. This study will provide insights on the timescales over which mafic magmas ascend to erupt explosively, which can be used to inform eruption response efforts and forecasts. The research team will collaborate with the U.S. Geological Survey’s Hawaiian Volcanic Observatory (HVO-USGS) to disseminate knowledge among global volcanic monitoring and risk assessment agencies. The work will also broaden the global use of geochemical techniques in volcano monitoring and response by supporting a module in the Center for the Study of Active Volcanoes (CSAV) summer course. This project will support graduate and undergraduate students through training in different micro-analytical techniques at Cornell and HVO, and their applications to understand eruptions. Results from this project will be incorporated into Earth Materials and Volcanology courses at Cornell. Finally, this project will enhance the infrastructure for research and education by establishing collaborations between Cornell University, HVO-USGS, the University of Manchester, LDEO-Columbia University, the University of Auckland, Caltech, and Syracuse University.High-intensity explosive eruptions (sub-Plinian, Plinian, and ultra-Plinian, with a volcanic explosivity index of 6+) result in global environmental effects and have great potential for devastating societal impacts. Among these eruptions, mafic eruptions are the least studied and represent a critical end-member urgently needing further investigation. Of particular interest is the determination of their magma decompression rates (dP/dt), as this parameter plays a crucial role in setting the style of volcanism in the eruption dynamics for basaltic magmas. This project will study the volatile evolution and decompression of basaltic Plinian to sub-Plinian eruptions. These eruptions represent some of basaltic volcanism's most catastrophic and least understood end-members. Reconstructing their eruption histories will address the following questions: 1) What is the record of pre-eruptive conditions and degassing that characterizes basaltic Plinian eruptions? To accurately constrain magmatic conditions, the evolution of volatile saturation and degassing before and during the eruption, and decompression pathways, the team will use olivine-hosted MIs. 2) What are the decompression rates of basaltic Plinian eruptions? Estimates of magma decompression rates for the proposed eruption case studies need to be improved or constrained indirectly using numerical models, experiments, and crystal textures. This work aims to complement the volatile evolution history with two petrological tools based on time-dependent chemical reactions: volatile diffusion across olivine-hosted embayments and concentration gradients of H+ in olivine crystals. 3) Do high-intensity mafic eruptions display a correlation between decompression rate and eruption magnitude? Current data suggest low and mildly explosive basaltic eruptions show a clear positive correlation between decompression rate and eruption magnitude. However, these data are not available for higher-magnitude eruptions. This project will answer this question with new decompression rates studies supplemented with literature data.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.