EAR-PF: Measuring the Effects of Large Volcanic Eruptions on a Shallow Magma Reservoir using Microanalytical Techniques

马德琳·刘易斯 (Madeline Lewis) 博士获得了 NSF EAR 博士后奖学金，以研究大型火山喷发如何影响地球表面下储存的潜在危险岩浆。她的研究、专业发展和公共宣传将在斯坦福大学与科学导师艾拉·帕慕克博士 (Ayla Pamukçu) 一起进行。火山中心与地壳内的岩浆储存库相连，但并非所有岩浆都会立即喷发。岩浆储存条件（压力、温度和溶解水含量）强烈影响岩浆喷发的可能性。然而，人们对喷发对岩浆储存条件的影响程度知之甚少。喷发后储存的岩浆是否容易移动并准备喷发，还是几乎凝固？刘易斯博士将利用内华达州已灭绝的斯蒂尔沃特火山口复合体（SCC）来解决这些问题，该复合体暴露了火山岩和现已凝固的岩浆储存系统的一部分。她将收集地球化学数据来计算SCC岩浆活动不同阶段的岩浆储存条件。刘易斯博士的早期研究确定了 SCC 岩浆活动的顺序和持续时间，她将用它来评估岩浆储存条件因重大喷发而发生的变化。刘易斯博士将通过设计一次虚拟实地考察来扩大她的工作的更广泛影响，这将通过斯坦福地球实地教育成为公开的教育资源。此外，她还将完成 STEM 教育培训，并志愿担任地球科学女性协会帕洛阿尔托分会的导师，以提高对追求地球科学学位和职业的女性的保留和支持。通过研究浅层硅质岩浆系统的侵入和喷出部分，可以改善火山口形成喷发后可喷发岩浆是否仍保留在浅层储存中的不确定性。内华达州渐新世（约 25 Ma）斯蒂尔沃特火山口复合体保留了一系列喷发前和喷发后的侵入体（约 106 年的岩浆历史），以及两个非常大（350 平方公里）的爆炸沉积物，记录了最终可喷发熔体的快照。刘易斯博士将收集并分析喷发（喷出）和未喷发（侵入）晶体和熔体包裹体的成分，以根据矿物平衡建立岩浆储存条件（例如温度、压力、挥发物含量）。她将把这些计算出的参数应用于基于热力学和扩散的模型，以估计岩浆结晶度和可喷发岩浆体的停留时间。将这些结果与她现有的高精度地质年代学数据相结合，将能够跟踪岩浆系统生命周期内的储层状况。如果发现火山喷发在浅层储层中留下了贫晶岩浆，则表明火山系统有能力在几乎没有地震预警的情况下产生“无声”喷发。相反，如果可喷发的岩浆在喷发后没有浅层保留，这对于将岩浆注入信号解释为即将喷发的指标具有重大意义。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Madeline Lewis has been awarded an NSF EAR Postdoctoral Fellowship to investigate how large volcanic eruptions affect potentially hazardous magma stored beneath the surface of the Earth. Her research, professional development, and public outreach will take place at Stanford University alongside scientific mentor Dr. Ayla Pamukçu. Volcanic centers are connected to magma storage reservoirs within Earth’s crust, yet not all magma is immediately eruptible. Magma storage conditions (pressure, temperature, and dissolved water content) strongly influence the potential for magma to erupt. However, the extent to which eruptions influence magma storage conditions is poorly understood. Is magma stored after an eruption easily mobile and primed to erupt, or is it nearly solidified? Dr. Lewis will address these questions using the extinct Stillwater Caldera Complex (SCC), Nevada, which exposes both volcanic rocks and portions of the now solidified magma storage system. She will collect geochemical data to calculate magma storage conditions during different stages of SCC magmatic activity. Dr. Lewis’s earlier research established the sequence and duration of magmatic activity in the SCC, which she will use to evaluate changes to the magma storage conditions in response to major eruptions. Dr. Lewis will expand the broader impacts of her work by designing a virtual field trip, which will be a publicly available educational resource through Stanford Earth Field Education. In addition, she will complete training in STEM education and volunteer as a mentor with the Palo Alto chapter of the Association for Women in Geoscience to improve retention and support for women pursing geoscience degrees and careers. The uncertainty surrounding whether eruptible magmas remain in shallow storage after caldera forming eruptions will be improved by investigating both the intrusive and extrusive portions of a shallow silicic magma system. The Oligocene (~25 Ma) Stillwater Caldera Complex, Nevada, preserves a sequence of pre- and post-eruptive intrusions (magmatic history of ~106 yrs), as well as two very large (350 km3) explosive deposits that record snapshots of definitively eruptible melts. Dr. Lewis will collect and analyze the compositions of erupted (extrusive) and unerupted (intrusive) crystals and melt inclusions to establish magma storage conditions (e.g., temperatures, pressures, volatile contents) from mineral equilibria. She will apply these calculated parameters to thermodynamic and diffusion-based models to estimate magma crystallinity and the residence time of eruptible magma bodies. Coupling these results with her existing high-precision geochronology data will enable tracking of reservoir conditions over the lifetime of the magma system. If eruptions are found to leave behind crystal-poor magmas in the shallow reservoir, this indicates the capacity of volcanic systems to produce “silent” eruptions with little seismic warning. Conversely, if eruptible magma is not retained shallowly after eruption, this has significant implications for interpretation of magma injection signals as an indicator of impending eruptions.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.