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扩散变形的原因。本研究将探讨北美科迪勒拉山脉早第三纪由地壳缩短向大范围伸展的构造转换的原因，变质核杂岩形成与盆山伸展的动力学关系，盆山伸展过程中应变局部化的控制和东加州剪切带的形成，构造变形的控制和构造变形的控制。4）板块边界带剪切耦合和盆地山脉重力塌陷在控制美国西部活动性地壳变形中的相对作用。将建立一系列准稳态地球动力学模型来探索驱动力、岩石圈结构以及在新生代演化的各个关键阶段控制美国西部大陆变形的关键构造边界条件。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级变化。粘塑性流变学将用于更好地模拟地壳中的应变局部化。 这些模型将使用有限元法和先进的算法和求解器建立，计算机代码将根据消息传递接口标准完全并行化，以便在功能强大的PC集群上有效运行。在地质学导出的地壳变形和板块边界演化的运动学边界条件的约束下，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，通过过去4000万年的各个关键阶段，这项研究将解决什么导致和控制扩散大陆变形的基本问题。板块构造理论预测，包括地壳变形和地震在内的构造过程都集中在沿着狭窄的板块边界。虽然这通常是正确的，但在许多板块边界，特别是在大陆上，发现了广泛的扩散变形。地壳变形从美国西部的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很重要，而且对地质灾害管理也很重要，因为广泛的地震活动，火山活动和山体滑坡都与这种变形有关。需要先进的计算机模型，如本研究中将要开发的模型，以整合和解释新观测技术和多学科研究倡议产生的大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