The Strength of Strike-Slip Fault Systems: Constraints from the Rock Record

板块边界断层系统（构造板块相互滑动的地方）是世界上最大的地震的所在地，也是渗透性和流体流经地壳的区域。我的团队研究断层系统中岩石和矿物变形的力学（从现场到纳米尺度），以约束地震周期，构造板块运动和岩石圈强度的模型。了解岩石和矿物如何变形是至关重要的，因为它直接控制长期（即，板块构造）和短期（即，地震周期）的演变，并通过产生地震，改变景观，形成/捕获自然资源（矿产，水文和碳氢化合物）影响社会。在接下来的五年里，我的团队将致力于确定中地壳到下地壳的走滑断层系统的强度。中地壳至下地壳的岩石通过韧性机制变形。中下地壳岩石的韧性变形与脆性上地壳的幕式变形耦合，后者产生地震。因此，了解韧性中下地壳岩石的强度是了解地震周期的基础。尽管它对地球动力学和地震物理学很重要，但中地壳到下地壳的强度却知之甚少，存在争议，并且有几个相互竞争的概念模型。评估断层系统强度的一种创新方法是使用古压力测量方法（即，古应力的测量）在中地壳到下地壳变形并在地质时期被挖掘到地球表面的岩石上。拟议的研究旨在批判性地评估测压方法并产生新的最佳方法，应用这些新的最佳方法来约束对岩石类型知之甚少的强度，并将观测结果整合到全球汇编中，以确定哪种地壳强度概念模型最适合数据。这项研究将由9名高素质的人员（5名本科生和4名硕士生）完成，他们将接受培训，使用现代数字现场方法和高质量的微量分析仪器，使他们成为工业界，学术界或政府调查的高技能资产。这项工作解决了结构地质学和构造学中的几个重大挑战，包括确定从地球表面到岩石圈底部的断层系统强度，以及更好地理解岩石圈中应力和应变之间的关系。

Plate boundary fault systems (where tectonic plates slide past one another) host the world's largest earthquakes and are zones of enhanced permeability and fluid flow through the crust of the Earth. My group studies the mechanics of rock and mineral deformation in fault systems (from the field- to nano-scale) to constrain models of the seismic cycle, tectonic plate motion, and the strength of the lithosphere. Understanding how rocks and minerals deform is critical because it directly controls the long term (i.e., plate tectonics) and short term (i.e., earthquake cycle) evolution of our planet, and impacts society by producing earthquakes, modifying landscapes, and forming/trapping natural resources (mineral, hydrological, and hydrocarbon). Over the next five years my group will work to determine the strengths of strike-slip fault systems in the middle to lower crust. Rocks in the middle to lower crust deform through ductile mechanisms. The ductile deformation of middle to lower crustal rocks is coupled to episodic deformation in the brittle upper crust which produces earthquakes. Understanding the strengths of ductile middle to lower crustal rocks is therefore fundamental to understanding the earthquake cycle. Despite its importance to geodynamics and earthquake physics, the strength of the middle to lower crust is poorly understood and controversial, and there are several competing conceptual models. One innovative way to assess fault system strength is to use paleopiezometric methods (i.e., measurements of paleo-stress) on rocks that deformed in the middle to lower crust and have been exhumed to Earth's surface over geologic time. The proposed research aims to critically assess piezometric methods and produce new best methods, apply these new best methods to constrain the strengths of poorly understood rock types, and to integrate observations into global compilations to determine which conceptual model of crustal strength best fits the data. The research will be completed by nine highly qualified personnel (5 undergraduates and 4 master's students), who will be trained to use modern digital field methods and high-quality microanalytical instruments, making them highly skilled assets for industry, academia, or government surveys. The work addresses several grand challenges in structural geology and tectonics, including determining fault system strength from Earth's surface to the base of the lithosphere and developing a better understanding of the relationship between stress and strain in the lithosphere.