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: 0948552
• 负责人: John Geissman
• 金额: $ 14.59万
• 依托单位: University of New Mexico
• 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 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948552&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.

在过去的12至15 Ma中，内华达州山脉相对于美国西部科迪勒拉大盆地的西北位移一直在进行。 这种运动是由一个复杂的和不完全理解的变形带，沿着大盆地的西缘，连接主要的，错位走滑断层在东部加州和西部内华达州。 根据以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平方公里的区域之下，并且包含大型构造块体，这些构造块体随着地壳被拉开而向西北方向平移，并且还经历20°至90°的垂直轴旋转。 在这个项目中，我们将提供一个更好的了解的构造块体的尺寸，多远，他们已经横向移动，到什么程度，他们经历了垂直轴旋转，以及时空模式的变形。 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。 本文的研究将有助于更好地理解大陆地壳在岩石圈板块相对运动的作用下如何以及在多大程度上适应了大地壳块体的平移和旋转。平移和旋转位移和应变的分量可调节大小横向断层，并产生复杂的三维结构阵列。 旋转和平移应变被刚性块体和/或分布应变调节的机制，以及平移和旋转过程在时空中耦合到什么程度，人们还知之甚少。 在本研究中，我们将详细的区域地质测绘与热年代学、构造和古地磁分析相结合，以揭示分隔内华达州和大盆地中部的横流构造的历史。 这项工作的目的是横向和高角度的正断层位移的特点，估计滑动低角度拆离断层，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所需的变形的空间和时间模式的详细了解和供应的约束条件，以区分同时期和串行平移和旋转变形的历史内的跨越系统，并提供评估是否或在何种程度上旋转是由刚体运动或分布式应变过程容纳的手段。