Collaborative Research: Timing, Extent, and Spatial Progression of Neogene Displacement Transfer, Southern Walker Lane, Western Great Basin

内华达山脉相对于美国西部科迪勒拉大盆地的西北部位移在过去12至15 Ma期间一直在进行。这一运动是由沿大盆地西缘的一条复杂且未被完全理解的变形带所适应的，该带连接着加利福尼亚州东部和内华达州西部的主要的错位走滑断层。根据前人的研究和我们的初步工作，我们已经确定该变形带位于近15,000平方公里的区域之下，并包含大型构造块体，这些构造块体在地壳拉裂时既向西北方向移动，又经历20°~90°的垂直轴旋转。在这个项目中，我们将更好地了解构造块的尺寸、它们横向移动的距离、它们经历了多大程度的垂直轴旋转以及形变的时空模式。北美西部边界的大部分地区和世界其他大陆的许多地区都处于类似的构造环境中，并记录了可比的形变历史。这项研究将使我们有机会更好地了解，随着大陆地壳因岩石圈板块的相对运动而碎裂，如何以及在多大程度上适应了大型地壳块体的平移和旋转。地壳对连接大型横流断层错位段的构造贫瘠中的位移转移的响应由平移和转动位移和应变的分量所调节，并导致复杂的三维结构阵列。旋转和平移应变通过刚性块和/或分布应变来调节的机制，以及平移和旋转过程在时空中耦合的程度，人们还知之甚少。在这项研究中，我们将详细的区域地质填图与热年代学、构造和古地磁分析相结合，以揭示分隔内华达山脉和大盆地中心的横流构造的历史。这项工作的目的是刻画横流和大角度正断层位移，估计小角度滑脱断层上的滑动，并评估平移变形和差异旋转之间的关系。我们的研究结果将提供对变形的空间和时间模式所需的详细了解，并提供限制条件以区分跨越式系统内的同时代和系列平移和旋转变形历史，并提供评估旋转是否或在多大程度上被刚体运动或分布应变过程所适应的手段。

Northwesterly displacement of the Sierra Nevada with respect to the Great Basin in the western US Cordillera has been ongoing for the last 12 to 15 Ma. This motion is accommodated by a complicated and incompletely understood belt of deformation along the western margin of the Great Basin that links major, misaligned strike-slip faults in eastern California and western Nevada. Based on previous research and our preliminary work, we have identified that the deformed belt underlies a region of nearly 15,000 km2 and contains large tectonic blocks that both translate toward the northwest as the crust is pulled apart and also undergo vertical-axis rotations of 20° to 90°. In this project, we will provide a better understanding of the dimensions of the tectonic blocks, how far they have moved laterally, to what degree they experienced vertical-axis rotation, and the spatial-temporal pattern of deformation. Much of the western borderland of North America and many parts of other continents around the world reside in similar tectonic settings and record comparable histories of deformation. This study will provide the opportunity to better understand how and to what degree the translation and rotation of large crustal blocks is accommodated as the continental crust is fragmented in response to the relative movement of lithospheric plates.Crustal response to displacement transfer in structural stepovers linking misaligned segments of large-magnitude transcurrent faults is accommodated by components of translational and rotational displacement and strain and results in complex three-dimensional arrays of structures. The mechanisms by which rotational and translational strain are accommodated either by rigid-blocks and/or by distributed strain and to what degree the translational and rotational processes are coupled in space-time are poorly understood. In this study, we integrate detailed and regional geologic mapping with thermochronologic, structural, and paleomagnetic analysis to unravel the history of transcurrent structures separating the Sierra Nevada and central Great Basin. The objective of the work is to characterize transcurrent and high-angle normal fault displacement, estimate slip on low-angle detachment faults, and assess the relation between translational deformation and differential rotation. Our research results will provide the needed detailed understanding of the spatial and temporal pattern of deformation and supply the constraints to differentiate between coeval and serial translational and rotational deformation histories within the stepover system and provide the means to assess whether or to what degree rotation is accommodated by rigid-body motion or distributed strain processes.