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

该奖项的全部或部分资金来自《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？我们将进行一项新的结合实地观察、实验室测量和数值模型模拟的综合研究，研究冰川和地形变化与智利几座活火山在过去50,000年间的行为之间的联系。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迅速消失如何影响这些火山的成分和喷发速度。该项目将为几名博士生提供职业发展经验。一个火山和冰川夏季项目将让来自美国和智利代表性较低群体的技校学生参与实地和实验室体验，包括针对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)加强对南美洲几个最危险的火山的增长率和喷发历史的了解，从而改进风险评估，(2)生成对校准我们的冰盖消退数字模型至关重要的新的气候代理数据，以及(3)培训居住在这些火山附近的社区的学生。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，我们的目标是耦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、体积和时间强烈地受到气候驱动的地表负荷变化的影响。这些短期反应调节了长期(100000年)平均喷发特征，这由地幔熔体流量控制；(2)与18,000年前局部快速冰川消融和侵蚀有关的地壳应力变化通过增强挥发分出溶促进喷发，而挥发分出溶反过来对储存的岩浆施加压力并推动岩墙向地表扩散；(3)对快速卸荷的反应在不同的火山之间会有所不同，反映了储存的岩浆的成分、挥发分含量和可压缩性以及地壳储藏从深处重新注入的速度的对比。这种可变性可以用来揭示冰川弧对气候系统的敏感性的基本控制。为了研究这些假设，我们将追求四个目标：(1)生成过去50,000年来沿俯冲带跨越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)建立由于六座火山邻近的沉积物的侵蚀、运输和沉积而产生的冰消退和景观演变的新记录，(3)使用火山、气候和地形记录中观察到的化学和物理模式来限制地壳负荷，并在数值模式中探索这种强迫的影响，以及(4)整合研究结果以了解大陆环境中的过程。并提供了一个框架，用于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。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.