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

板块边界断层系统(其中构造板块相互滑动)是世界上最大的地震的发源地，是渗透性增强和流体通过地壳流动的地带。我的团队研究断层系统中岩石和矿物变形的机制(从野外到纳米级)，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至关重要，因为它直接控制着地球的长期(即板块构造)和短期(即地震周期)演化，并通过引发地震、改变景观和形成/捕获自然资源(矿物、水文和碳氢化合物)来影响社会。在接下来的五年里，我的团队将致力于确定中下地壳走滑断层系统的强度。中下地壳中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在一起，从而产生地震。因此，了解韧性中、下地壳岩石的强度是理解地震周期的基础。尽管中下地壳的强度对地球动力学和地震物理很重要，但人们对它的了解很少，也存在争议，而且有几个相互竞争的概念模型。一种评估断裂系统强度的创新方法是对在中下地壳变形并在地质时期被挖掘到地球表面的岩石使用古地层测量方法(即古应力测量)。这项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限制鲜为人知的岩石类型的强度，并将观测结果整合到全球汇编中，以确定哪种地壳强度的概念模型最符合数据。这项研究将由9名高素质人员(5名本科生和4名硕士学生)完成，他们将接受使用现代数字现场方法和高质量微量分析仪器的培训，使他们成为工业、学术界或政府调查的高技能资产。这项工作解决了构造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.