Tracking ascent rates in an open-vent volcano: Testing textural and geochemical ascent speedometers

跟踪露天火山的上升速率：测试结构和地球化学上升速度计

• 批准号: 2147714
• 负责人: Philipp Ruprecht
• 金额: $ 26.83万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147714&HistoricalAwards=false
• 关键词: Tracking; ascent; rates; open; vent

Volcanic eruptions are sourced from magma chambers in the crust. At what depth magmas are stored and how fast they move to the surface prior to an eruption is of great importance to assess the hazards associated with individual volcanoes. Open-vent volcanoes are particularly hazardous for their lack of unrest signals prior to an eruption. This project specifically focuses the 2018 eruption of the open-vent volcano Mt Veniaminof on the Alaska Peninsula, which poses substantial risk to local communities and aviation through ash emissions. Volatile elements that exsolved on ascent (especially H2O) are the drivers of explosive eruptions. Thus, constraining the volatile element budget in these magmas as well as how fast the volatiles are lost provide important constraints for eruption models and the eruptive behavior of this and similarly behaving volcanoes. A variety of techniques are used to estimate magma ascent and in this study, those techniques will be compared to improve their robustness and test their underlying assumptions. In addition to the scientific benefits, this project will foster collaboration between the USGS/AVO and the academic community, while this collaboration will ensure that existing data sets and samples will continue to be exploited. The Alaska Peninsula is a focus site of geologic research (GeoPRISMS) and our work will complement ongoing geophysical research activities (Amphibious Array). Volatile element data is of importance for geophysics and will inform crustal and upper mantle seismic and magnetotelluric studies. The project supports a collaboration with journalism colleagues to improve science communication and help build a new generation of science-literate journalists. The interplay between magma ascent and textural evolution of basaltic andesites of the 2018 Veniaminof eruption will be studied. Existing estimates for magma ascent rates during the 2018 eruption derived from microlites, will be compared against independently determined ascent rates from melt embayments hosted in olivine. To interpret the embayment and textural record, we will also collect melt inclusion volatile data to constrain the volatile element budget in the crustal storage region prior to ascent. The work includes a series of analytical techniques (Raman, x-ray computed tomography, SIMS, FTIR, EPMA, LA-ICPMS) to fully characterize and correct the volatile budget. Fundamental assumptions related to embayment studies will be tested: 1) the uniformity of ascent rates among embayments, 2) changes over the course of an eruptive episode, 3) the effect of embayment necking. The project will be complemented with the development of a thermodynamic model that captures the driving forces for crystallization and dissolution through the calculation of chemical affinities along any preferred P-T-X-time path.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.

火山喷发来自地壳中的岩浆室。在岩浆中存储了什么深度岩浆，以及在喷发前向表面移动的速度，对于评估与单个火山相关的危害非常重要。开放式火山在喷发前缺乏动乱信号特别危险。该项目专门集中于2018年在阿拉斯加半岛上开放式火山火山山的爆发，这通过灰分排放给当地社区和航空带来了重大风险。在上升时出现的挥发性元素（尤其是H2O）是爆炸的驱动因素。因此，限制这些岩浆中的挥发性要素预算以及浪费的速度损失的速度为喷发模型和该爆发行为和类似行为的火山提供了重要的限制。使用多种技术来估计岩浆上升，在这项研究中，将进行比较以提高其鲁棒性并测试其基本假设。除了科学的好处外，该项目还将促进USGS/AVO与学术界之间的合作，而该合作将确保现有的数据集和样本将继续被利用。阿拉斯加半岛是地质研究的重点地点（地理化主义），我们的工作将补充正在进行的地球物理研究活动（两栖阵列）。挥发性元素数据对于地球物理学至关重要，将为地壳和上地幔地震和磁铁性研究提供信息。该项目支持与新闻业同事的合作，以改善科学沟通并帮助建立新一代的科学识字记者。将研究岩浆上升与质地演化之间的相互作用，并研究2018年爆发的玄武岩安山岩。将岩浆上升速率的现有估计值与从橄榄石中宿主的熔体嵌入的独立上升速率进行比较。为了解释嵌入和纹理记录，我们还将收集融合的挥发性数据，以限制上升前地壳存储区域的挥发性元素预算。这项工作包括一系列分析技术（拉曼，X射线计算机断层扫描，SIMS，FTIR，EPMA，LA-ICPMS），以完全表征和纠正挥发性预算。将测试与胚胎研究有关的基本假设：1）胚胎之间上升速率的均匀性，2）在喷发性发作过程中的变化，3）胚胎颈部的效果。该项目将与热力学模型的开发相辅相成，该模型通过沿任何首选的P-T-X时间路径的化学亲和力来捕获驱动力，以捕获结晶和溶解。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的智力和更广泛影响的评估来通过评估来获得支持的，并被认为是值得的。