Collaborative Research: Ice Forcing in Arc Magma Plumbing Systems (IF-AMPS)

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。地球科学的一个前沿问题是：地球表面气候系统的变化是如何与地球内部的岩浆库相互作用的？我们将对冰川和地形变化之间的联系以及过去5万年智利几座活火山的行为进行一项综合研究，将实地观测、实验室测量和数值模型模拟结合起来。这些火山部分被3000英尺厚的巴塔哥尼亚冰盖覆盖，直到18000年前冰盖迅速融化。这个天然实验室提供了无与伦比的手段来研究冰的迅速消失是如何影响这些火山的成分和喷发速度的。该项目将为几名博士生提供职业发展经验。一个火山和冰川暑期项目将吸引来自美国和智利代表性不足群体的技术学校学生进行实地和实验室体验，包括无人机技术数据收集和地质测绘的培训。我们与智利科学家和教育工作者的合作旨在：(1)提高对南美洲几座最危险火山的增长率和喷发历史的了解，从而改进危害评估；(2)生成新的气候代理数据，这对校准我们的冰盖退缩数值模型至关重要；(3)培训生活在这些火山附近社区的学生。利用安第斯南部火山区内新的和现有的地质年代学、地球化学、冰川和侵蚀/沉积观测，我们的目标是将一套数值模型结合起来，以测试和完善三个假设：(1)在短时间尺度（10万年）内，火山喷发的组成、体积和时间受到气候驱动的地表负荷变化的强烈影响。这些短期响应调节了长期（10万年）平均喷发特征，这些特征受地幔熔体通量控制；(2)与1.8万年前局部快速消冰和侵蚀有关的地应力变化，通过增强挥发性析出促进了喷发，挥发性析出反过来又对储存的岩浆施加压力并推动岩脉向地表扩展；(3)不同火山对快速卸载的响应不同，反映了成分的差异。挥发性含量，储存岩浆的可压缩性，以及地壳储层从深处补给的速率。这种变率可以用来揭示冰川弧对气候系统敏感性的基本控制。为了调查这些假设，我们将追求四个目标：(1)生成近5万年来横跨250 km俯冲带的6座火山的锥生长、喷发行为和地球化学演化的高分辨率记录；(2)建立6座火山附近沉积物侵蚀、搬运和沉积导致的冰退缩和景观演化的新记录；(3)利用火山、气候和地形记录中观测到的化学和物理模式来约束地壳随时间的加载。(4)将研究结果整合到大陆背景下的过程中，并提供一个框架，用于研究其他地方和整个地球历史上一系列气候状态下弧火山作用对外部强迫的敏感性。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。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).A question at the frontier of Earth science is: how do changes in the climate system on our planet's surface interact with magma reservoirs housed within its interior? We will conduct a novel blend of field observations, lab measurements, and numerical model simulations in an integrated study of links between changes in glaciers and topography, and the behavior of several active volcanoes in Chile during the last 50,000 years. These volcanoes were partly covered by the 3,000 foot thick Patagonian ice sheet until it melted rapidly beginning 18,000 years ago. This natural laboratory offers unparalleled means to investigate how the rapid loss of ice impacted the composition and rates of eruptions from these volcanoes. This project will provide career-building experience for several PhD students. A volcano & ice Summer program will engage technical school students from underrepresented groups in the US and Chile in field- and lab-based experiences, including training in drone technology for data collection and geologic mapping. Our collaborations with Chilean scientists and educators aim to: (1) enhance knowledge of the growth rates and eruptive histories of several of the most dangerous volcanoes in South America, thereby improving hazard assessment, (2) generate new climate proxy data critical to calibrating our numerical model of ice sheet retreat, and (3) train students from the communities living near these volcanoes. Utilizing new and existing geochronologic, geochemical, glacial and erosion/deposition observations within the Andean Southern Volcanic Zone, we aim to couple a suite of numerical models to test and refine three hypotheses: (1) Over short timescales (100,000 year), the composition, volume, and timing of eruptions are strongly influenced by climate-driven changes in surface loading. These short-term responses modulate the long-term (100,000 year) average eruptive characteristics, which are governed by mantle melt flux, (2) Crustal stress changes associated with the local onset of rapid deglaciation and erosion at 18,000 years ago promoted eruptions by enhancing volatile exsolution that in turn pressurized stored magma and propelled dike propagation to the surface, and (3) Responses to rapid unloading will vary among volcanoes, reflecting contrasts in the composition, volatile contents, and compressibility of stored magma, as well as the rate at which crustal reservoirs are recharged from depth. This variability can be exploited to reveal fundamental controls on the sensitivity of glaciated arcs to the climate system. To investigate these hypotheses, we will pursue four objectives: (1) Generate high-resolution records of cone growth, eruptive behavior, and geochemical evolution of six volcanoes during the last ~50,000 years spanning 250 km along the subduction zone, (2) Build new records of ice retreat, and landscape evolution owing to the erosion, transport, and deposition of sediment adjacent to the six volcanoes, (3) Use the observed chemical and physical patterns in the volcanic, climatic, and topographic records to constrain crustal loading through time, and explore the effects of this forcing in numerical models, and (4) Integrate findings to contextualize processes in continental settings, and provide a framework for examining the sensitivity of arc volcanism to external forcing elsewhere and across a spectrum of climate states throughout Earth history.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.