Global plate tectonics and mantle convection with damage memory

板块构造是地球演化和地幔对流地表表现的基础。然而，目前还不清楚更坚硬的板之间狭窄和强烈变形的边界是如何形成的。特别是板块边界的重新激活，给大陆板块带来了长期的滞后，对构造学有着深远的影响。该项目旨在更好地理解对流中损伤记忆的原因和后果。资助将支持一名女研究生，并就地球动力学以外的问题发表演讲，包括寻求描述从地震周期到地球长期演化的断层行为的一般规律。该项目还将支持新的国际合作，研究成果将得到广泛传播，包括德克萨斯大学奥斯汀分校的GeoFORCE K-12推广计划。该项目将在全球数值对流模式中实施应变相关的减弱，以探索由粘塑性地幔流动产生的“板块构造”风格。结合这种流变性记忆将允许研究全面的构造行为，包括板块边界演化和板块运动如何与深部地幔联系在一起。将探索一系列粘性损伤公式，并以颗粒尺寸演化理论和其他建议的应变局部化机制为基准，例如由于橄榄石晶格择优取向而形成的剪切带和机械各向异性。模型结果将与包括板块运动学在内的地质约束进行比较，特别侧重于板块边界几何形状、板块速度和大小以及海底年龄分布随时间的变化。总体目标是从理论上理解构造继承在类地行星演化和热传输中的作用。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。

Plate tectonics is fundamental for Earth's evolution and the surface expression of mantle convection. However, it is unclear how the narrow and strongly deforming boundaries between the more rigid plates form. The reactivation of plate boundaries, in particular, gives the continental plates a long-term hysteresis with profound implications for tectonics. This project seeks to better understand the causes and consequences of damage memory in convection. Funding will support a female graduate student and speak to issues outside geodynamics including the quest for a general law describing fault behavior from the seismic cycle to long-term Earth evolution. The project will also support new international collaborations, and research outcomes will be disseminated widely, including for UT Austin's GeoFORCE K-12 outreach program.This project will implement strain-dependent weakening into global, numerical convection models in order to explore the style of "plate tectonics" that is generated by visco-plastic mantle flow. Incorporating such rheological memory will allow study of the full range of tectonic behavior, including how plate boundary evolution and plate motions are linked with the deep mantle. A range of viscous damage formulations will be explored and benchmarked against grain-size evolution theories and other suggested mechanisms for strain-localization, such as formation of shear bands and mechanical anisotropy due to lattice preferred orientation of olivine. Model results will be compared with geological constraints including plate kinematics, with particular focus on the time-dependence of plate boundary geometry, plate speeds and sizes, and seafloor age distributions. The overall goal is to develop a theoretical understanding of the role of tectonic inheritance in terrestrial planet evolution and heat transport.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.