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

该奖项的全部或部分资金来源于《2021 年美国救援计划法案》（公法 117-2）。地球科学前沿的一个问题是：地球表面气候系统的变化如何与其内部的岩浆库相互作用？我们将采用现场观测、实验室测量和数值模型模拟的新颖方式，对过去 5 万年来冰川和地形变化以及智利几座活火山的行为之间的联系进行综合研究。这些火山部分被 3,000 英尺厚的巴塔哥尼亚冰盖覆盖，直到 18,000 年前开始迅速融化。这个自然实验室提供了无与伦比的手段来研究冰的快速流失如何影响这些火山的成分和喷发率。该项目将为几名博士生提供职业建设经验。火山与冰夏季计划将让来自美国和智利代表性不足群体的技术学校学生参与实地和实验室体验，包括用于数据收集和地质测绘的无人机技术培训。我们与智利科学家和教育工作者的合作旨在：(1) 增强对南美洲几座最危险火山的增长率和喷发历史的了解，从而改进灾害评估；(2) 生成新的气候代理数据，这对于校准我们的冰盖退缩数值模型至关重要；(3) 培训来自这些火山附近社区的学生。利用安第斯南部火山带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，我们的目标是结合一套数值模型来测试和完善三个假设：（1）在短时间尺度（10万年）内，喷发的成分、体积和时间受到气候驱动的表面负荷变化的强烈影响。这些短期反应调节长期（100,000年）平均喷发特征，该特征受地幔熔体通量控制，（2）与18,000年前局部快速消融和侵蚀相关的地壳应力变化通过增强挥发性出溶促进喷发，进而加压储存的岩浆并推动岩脉传播到地表，以及（3）火山之间对快速卸荷的反应会有所不同，反映了储存岩浆的成分、挥发性含量和可压缩性的对比，以及地壳储层从深度补给的速率。可以利用这种变化来揭示冰川弧对气候系统敏感性的基本控制。为了研究这些假设，我们将追求四个目标：(1) 生成过去约 50,000 年中沿着俯冲带跨越 250 公里的六座火山的锥体生长、喷发行为和地球化学演化的高分辨率记录，(2) 建立冰退缩的新记录，以及由于六座火山附近沉积物的侵蚀、迁移和沉积而导致的景观演化，(3) 使用在火山、气候和地形记录中观察到的化学和物理模式随着时间的推移限制地壳载荷，并探索这种强迫在数值模型中的影响，以及（4）整合研究结果以将大陆环境中的过程联系起来，并提供一个框架来检查弧火山活动对其他地方和整个地球历史上一系列气候状态的外部强迫的敏感性。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。

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.