MCA: Destroying continental plates - unraveling the role of magmatism

板块构造学的一个基本思想是，大部分的“活动”（地震、火山、断层）发生在板块边界，构造板块的内部是稳定的、不变形的。虽然这对大陆内部（如北美）来说基本是正确的，但地质证据表明，在适当的情况下，先前稳定的大陆构造板块会变形、运动，并可能分裂——伴随着板块内部的地震和火山活动。这个项目将研究可能导致这种不稳定的关键过程之一：浮力强、热的熔融岩石（岩浆）渗透到大陆构造板块的底部。该项目将探索岩浆在渗透时如何与大陆地幔岩石相互作用，以及这种熔融岩石相互作用如何深刻地改变构造板块。该奖项将为面临研究障碍的处于职业生涯中期的女性科学家提供研究和职业提升，使她能够重返前沿研究领域。此外，该项目将培训两名女研究生（其中一名有残疾记录），包括批判性思维、数据分析、数值建模和机器学习，为培养多样化、具有全球竞争力的STEM劳动力做好准备。总体而言，该项目将提高妇女、残疾人和代表性不足的少数民族在STEM领域的参与度。该项目将结合数据分析、数值模拟和机器学习，对岩浆渗入大陆地幔岩石圈过程中热和化学不平衡的后果进行以过程为导向的理解。该团队将利用北美西南部新生代火山岩地球化学的最新见解来确定岩浆渗透如何帮助岩石圈的物理和化学状态的逐步转变：从早期（60 Ma）与俯冲有关的变形和岩浆作用到当前（20 Ma后）的伸展/张拉和相关岩浆作用状态。该研究将验证北美西南部新生代物理和化学状态的转变反映在区域一致的火山岩成分转变上，特别是在Ta/Th值上。以这种转变为起点，将开发一种统计方法，以揭示火山岩成分中的其他模式，以确定岩浆-岩石圈相互作用的不同风格。与监督学习类似，该团队将“训练”其在北美典型火山岩化学和同位素模式上的统计方法，然后将这些方法应用于来自青藏高原的“测试”数据，青藏高原是另一个具有丰富的新生代大陆火山活动和岩石圈退化的地区。地球化学解释将为渗透岩浆与周围岩石圈地幔之间的热化学不平衡的数值模型提供信息。这种综合方法将对岩浆-岩石圈相互作用及其在改造和潜在退化先前稳定的大陆岩石圈中的作用产生过程导向的理解。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。

A fundamental idea of plate tectonics is that most of the ‘action’ (earthquakes, volcanoes, faulting) happens at plate boundaries and that the interiors of tectonic plates are stable and undeforming. While this is mostly true for the interiors of continents (such as North America), geologic evidence shows that under the right circumstances previously stable continental tectonic plates can deform, mobilize and possibly rift apart—with accompanying plate-interior earthquake and volcanic activity. This project will investigate one of the key processes that may lead to this destabilization: the infiltration of buoyant, hot, molten rock (magma) into the base of a continental tectonic plate. This project will explore how magma interacts with the continental mantle rocks as it infiltrates and how such melt-rock interaction may profoundly alter tectonic plates. This award will provide research and career enhancement to a female mid-career scientist who has faced barriers to research, allowing her to return to cutting-edge research. Additionally, the project will train two female graduate students (one of whom has a documented disability) in critical thinking, data analysis, numerical modeling, and machine learning, preparing them to contribute to a diverse, globally competitive STEM workforce. Overall, the project will enhance the participation of women, persons with disabilities, and underrepresented minorities in STEM. This project will combine data analysis, numerical modeling, and machine learning to develop a process-oriented understanding of the consequences of thermal and chemical disequilibrium during magma-infiltration into the continental mantle lithosphere. The team will exploit recent insights from the geochemistry of Cenozoic volcanic rocks in southwestern North America to determine how magma-infiltration aided in a progressive transformation of the physical and chemical state of the lithosphere: from earlier (60 Ma) subduction-related deformation and magmatism to the current (post 20 Ma) state of extension/transtension and associated magmatism. The research will test the idea that the Cenozoic transition in the physical and chemical state of southwestern North America is reflected in a regionally-consistent compositional transition in volcanic rocks, specifically in Ta/Th values. Using this transition as a starting point, a statistical methodology will be developed for uncovering other patterns in volcanic rock compositions in order to identify different styles of magma-lithosphere interaction. In analogy with supervised learning, the team will “train” its statistical methods on canonical volcanic rock chemical and isotopic patterns in North America, and then will apply these methods to “test” data from the Tibetan Plateau, another region of abundant Cenozoic continental volcanism and lithosphere degradation. The geochemical interpretations will inform numerical models of thermal and chemical disequilibrium between infiltrating magma and the surrounding lithospheric mantle. This integrative approach will yield a process-oriented understanding of magma-lithosphere interaction and its role in modifying and potentially degrading previously stable continental lithosphere.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.