A Four-Dimensional Geodynamic Reconstruction of Cenozoic Tectonics in the Western United States

这项研究的目的是了解美国西部大陆弥漫变形的原因。这项研究将解决以下问题：1)北美科迪勒拉地区早第三纪构造由地壳缩短向广泛伸展转变的原因；2)变质核杂岩建造与盆地和山脉伸展的动力学关系；3)盆地应变局部化的控制和东加州剪切带的伸展和启动；4)板块边界剪切耦合和盆地重力塌陷在控制美国西部地壳活动变形中的相对作用。将开发一系列准稳态地球动力学模型，以探索在美国西部新生代演化的各个关键阶段控制大陆变形的驱动力、岩石圈结构和关键构造边界条件。这些模型将是完全三维的，具有足够的空间分辨率，以纳入包括主要断裂带在内的岩石圈结构的重要一阶变化。为了更好地模拟地壳中的应变局部化，将使用粘塑性流变学。模型将使用有限元方法和先进的算法和求解器建立，计算机代码将基于消息传递接口标准完全并行化，以便在功能强大的PC集群上高效运行。受地壳变形和板块边界演化的地质学运动边界条件的约束，这套模型将产生美国西部新生代构造演化的三维地球动力学重建，它经历了近4000万年来的各个关键阶段。这项研究将解决什么原因和控制扩散大陆变形的根本问题。板块构造理论预测，包括地壳变形和地震在内的构造过程集中在狭义的板块边界上。虽然这通常是正确的，但在许多板块边界发现了广泛的弥散变形，特别是在大陆。在美国西部，地壳变形从板块边界延伸数千公里。了解这种扩散变形的动力学不仅对地球科学，而且对地质灾害管理都很重要，因为广泛的地震活动、火山活动和滑坡都与这种变形有关。需要先进的计算机模型，例如将在本研究中开发的模型，以便能够集成和解释由新的观测技术和多学科研究倡议产生的大容量多尺度三维数据集

The goal of this research is to understand the cause of diffuse continental deformation in the western United States. This study will address the following problems: 1) The cause of Early Tertiary tectonic transition from crustal shortening to widespread extension in the North American Cordillera; 2) dynamic relationship between metamorphic core-complex formation to Basin and Range extension; 3) control of strain localization during the Basin and Range extension and initiation of the Eastern California Shear Zone; and 4) the relative roles of shear coupling across the plate boundary zone and gravitational collapse of the Basin and Range in controlling active crustal deformation in the western U.S. A sequence of quasi steady-state geodynamic models will be developed to explore the driving forces, lithospheric structures, and key tectonic boundary conditions that control continental deformation in the western U.S. at various critical stages of its Cenozoic evolution. These models will be fully three-dimensional with sufficient spatial resolution to incorporate important first-order variations of lithospheric structure including major fault zones. Viscoplastic rheology will be used for better simulation of strain localization in the crust. The models will be built using the finite element method with advanced algorithm and solvers, and the computer codes will be fully parallelized based on the Message Passing Interface standards to run efficiently on powerful PC clusters. Constrained by geologically derived kinematic boundary conditions of crustal deformation and plate boundary evolution, this suite of models will produce a 3D geodynamic reconstruction of Cenozoic tectonic evolution in the western U.S. through various critical stages in the last 40 million years.This research will address the fundamental question of what causes and controls diffuse continental deformation. Plate tectonics theory predicts that tectonic processes, including crustal deformation and earthquakes, are concentrated along narrowly-defined plate boundaries. While this is generally true, broad diffuse deformation is found in many plate boundaries, especially in the continents. Crustal deformation extends thousands of kilometers from the plate boundary in western U.S. Understanding the dynamics of such diffuse deformation is important not only for geosciences but also for geohazards management, because widespread seismicity, volcanism, and landslides are associated with such deformation. Advanced computer models, such as the ones to be developed in this research, are needed to enable integration and interpretation of large volume multi-scale three-dimensional data sets generated by new observational technologies and multidisciplinary research initiatives