MCA: Destroying continental plates - unraveling the role of magmatism

MCA：摧毁大陆板块——揭示岩浆作用的作用

• 批准号: 2120812
• 负责人: Mousumi Roy
• 金额: $ 32.42万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2120812&HistoricalAwards=false
• 关键词: MCA; Destroying; continental; plates; unraveling

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.

板块构造学的基本思想是，大多数“活动”（地震、火山、断层）发生在板块边界，并且构造板块的内部是稳定且不变形的，而对于大陆内部来说，这基本上是正确的。地质证据表明，在适当的情况下，先前稳定的大陆板块可能会变形、移动，甚至可能裂开，并伴随着板块内部地震和火山活动。将研究可能导致这种不稳定的关键过程之一：有浮力的热熔岩（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中期女性科学家提供研究和职业提升，使她能够重返地球。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对两名女研究生（其中一名有残疾记录）进行培训，帮助她们为多元化、具有全球竞争力的 STEM 劳动力队伍做出贡献该项目将加强妇女、残疾人和代表性不足的少数群体对 STEM 的参与。该项目将结合数据分析、数值建模和机器学习，以形成对岩浆期间热和化学不平衡后果的面向过程的理解。 -渗透到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物理和化学状态的逐步转变：从早期（60 Ma）俯冲开始。与当前（20 Ma 后）伸展/变形状态相关的变形和岩浆作用以及相关的岩浆作用该研究将检验新生代过渡的观点。北美西南部物理和化学状态的变化反映在火山岩中区域一致的成分转变中，特别是 Ta/Th 值，以这种转变为起点，将开发一种统计方法来揭示火山岩中的其他模式。与监督学习类似，该团队将根据北美的典型火山岩化学和同位素模式“训练”其统计方法。将应用这些方法来“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，地球化学解释将为渗透岩浆与周围岩石圈地幔之间的热和化学不平衡的数值模型提供信息。产生对岩浆-岩石圈相互作用及其在改变和潜在降解先前稳定的大陆岩石圈中的作用的面向过程的理解。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Assessing the role of thermal disequilibrium in the evolution of the lithosphere–asthenosphere boundary: an idealized model of heat exchange during channelized melt transport

评估热不平衡在岩石圈-软流圈边界演化中的作用：通道化熔体传输过程中热交换的理想化模型

• DOI: 10.5194/se-13-1415-2022
• 发表时间: 2022
• 期刊: Solid Earth
• 影响因子: 3.4
• 作者: Roy, Mousumi