Lundstern Jens-Erik, Zoback Mark D
Department of Geophysics, Stanford University, 397 Panama Mall, Mitchell Bld. 3rd Flr., Stanford, CA, 94305, USA.
Geosciences and Environmental Change Science Center, U.S. Geological Survey, P.O. Box 25046, MS 980, Denver, CO, 25046, USA.
Nat Commun. 2020 Apr 23;11(1):1951. doi: 10.1038/s41467-020-15841-5.
The Earth's crustal stress field controls active deformation and reflects the processes driving plate tectonics. Here we present the first quantitative synthesis of relative principal stress magnitudes throughout North America together with hundreds of new horizontal stress orientations, revealing coherent stress fields at various scales. A continent-scale transition from compression (strike-slip and/or reverse faulting) in eastern North America to strike-slip faulting in the mid-continent to predominantly extension in western intraplate North America is likely due (at least in part) to drag at the base of the lithosphere. Published geodynamic models, incorporating gravitational potential energy and tractions from plate motions or relative mantle flow, successfully predict most large-wavelength stress rotations but not the shorter-wavelength (<~200 km) rotations observed in the western USA. The stresses resulting from glacial isostatic adjustment appear to be much smaller than the magnitude of ambient tectonic stresses in the crust at depth.
地壳应力场控制着活动变形，并反映了驱动板块构造的过程。在此，我们首次对整个北美地区的相对主应力大小进行了定量综合分析，并给出了数百个新的水平应力方向，揭示了不同尺度上的连贯应力场。北美大陆尺度上从东部的压缩（走滑和/或逆断层作用）到中部大陆的走滑断层作用，再到北美西部板内主要为伸展作用的转变，可能（至少部分）是由于岩石圈底部的拖曳作用。已发表的地球动力学模型，结合了引力势能以及板块运动或相对地幔流产生的牵引力，成功预测了大多数大波长的应力旋转，但未能预测到美国西部观测到的较短波长（<~200 km）的旋转。冰川均衡调整产生的应力似乎远小于地壳深部的环境构造应力大小。
