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

合作研究：西部大盆地沃克巷南部新近纪位移转移的时间、范围和空间进展

• 批准号: 0948542
• 负责人: John Oldow
• 金额: $ 19.98万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-15 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948542&HistoricalAwards=false
• 关键词: Collaborative; Research; Timing; Extent; Spatial

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.

内华达山脉相对于美国西部科迪勒拉的大盆地向西北移动已经持续了12到15 Ma。这种运动是由沿大盆地西缘的一条复杂的、尚不完全了解的变形带所调节的，这条变形带连接着加州东部和内华达州西部的主要的、错位的走滑断层。根据先前的研究和我们的初步工作，我们已经确定变形带位于近15,000平方公里的区域下方，其中包含大型构造块，这些构造块在地壳撕裂时向西北方向平移，并且还经历了20°至90°的垂直轴旋转。在这个项目中，我们将更好地了解构造块体的尺寸，它们横向移动了多远，它们经历了多大程度的垂直轴旋转以及变形的时空格局。北美西部边界的大部分地区和世界上其他大陆的许多地区都处于类似的构造环境中，并记录了类似的变形历史。这项研究将为更好地理解大陆地壳因岩石圈板块的相对运动而破碎时，大型地壳块体的平移和旋转是如何以及在多大程度上被适应的提供机会。在连接大震级横向断层错位段的构造断层中，地壳对位移传递的响应由平移和旋转位移和应变分量调节，从而形成复杂的三维构造阵列。转动和动应变由刚性块和/或分布应变调节的机制以及平移和动过程在时空中的耦合程度尚不清楚。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，揭示了分隔内华达山脉和中部大盆地的横向构造的历史。该工作的目的是表征横流和高角度正断层位移，估计低角度滑脱断层的滑动，并评估平移变形与差旋之间的关系。我们的研究结果将提供对变形空间和时间模式的详细了解，并提供区分同步和连续平移和旋转变形历史的约束条件，并提供评估刚体运动或分布应变过程是否或在多大程度上适应旋转的方法。