MCA: Destroying continental plates - unraveling the role of magmatism

板块构造学的一个基本观点是，大多数‘作用’(地震、火山、断层)发生在板块边界，构造板块内部是稳定和不变形的。虽然大陆内部(如北美)的情况大多如此，但地质证据表明，在适当的情况下，以前稳定的大陆构造板块可以变形、移动，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：漂浮的、热的、熔岩(岩浆)渗入大陆构造板块的底部。这个项目将探索岩浆在渗入时如何与大陆地幔岩石相互作用，以及这种熔岩相互作用如何深刻地改变构造板块。该奖项将为一位面临研究障碍的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。此外，该项目将在批判性思维、数据分析、数值建模和机器学习方面培训两名女研究生(其中一名有记录的残疾)，为她们为多元化、具有全球竞争力的STEM劳动力做出贡献做好准备。总体而言，该项目将加强妇女、残疾人和代表不足的少数群体在STEM中的参与。该项目将结合数据分析、数值模拟和机器学习，以过程为导向理解岩浆渗入大陆地幔岩石圈期间热和化学不平衡的后果。该小组将利用北美西南部新生代火山岩的最新发现，确定岩浆渗透如何有助于岩石圈的物理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，到目前(20 Ma后)的伸展/拉张和相关的岩浆活动状态。这项研究将检验这一观点，即北美西南部物理化学状态的新生代转变反映在火山岩中区域一致的成分转变中，特别是在Ta/Th值上。以这一转变为起点，将开发一种统计方法，以揭示火山岩成分的其他模式，以确定不同类型的岩浆-岩石圈相互作用。与监督学习类似，该团队将对其在北美典型的火山岩化学和同位素模式的统计方法进行“培训”，然后将这些方法用于“测试”来自青藏高原的数据，青藏高原是另一个新生代大陆火山活动和岩石圈退化丰富的地区。这些地球化学解释将提供渗入岩浆与周围岩石圈地幔之间热不平衡和化学不平衡的数值模型。这一综合方法将对岩浆-岩石圈相互作用及其在改变和潜在退化先前稳定的大陆岩石圈中的作用产生面向过程的理解。该奖项反映了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。

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.