Collaborative Research: Determination of Slip Rates on the Death Valley-Fish Lake Valley Fault System: Toward an Understanding of the Spatial & Temporal Extent of Strain Transi

断层加载和应变释放速率在时间和空间上恒定(或非恒定)的程度是现代地球动力学中最基本、最悬而未决的问题之一。短期大地测量数据与长期(百万年)全球板块运动数据的比较表明，沿大多数板块边界，应变的储存和释放在大的时间范围内是相对连续的。然而，最近对加州东部剪切带莫哈韦段的大地测量和地质速率数据的比较表明，发生了显著的应变瞬变。这些观察提出了几个基本的重要问题，即应变是如何沿着主要的板块边界断层系统累积和释放的。来自南加州大学、辛辛那提大学和加州大学伯克利分校的一组科学家试图了解加州东部剪切带北半部应变积累和释放的时空稳定性。具体地说，这项工作将集中在死亡谷-鱼湖谷断裂带，这是该地区最大的断层系统，从加洛克断层向北延伸300多公里，一直延伸到内华达州西南部。通过用宇宙成因核素测年和光激发发光年代学确定沿断层系统长度的各种地质时间尺度(1000年至100000年)的断层滑动速率。变形的地貌特征是基于机载激光条带测绘数字地形数据识别、绘制和恢复的，这些数据是在沿断层的两公里宽的条带中获得的，以使研究小组能够确定断裂带的地貌背景，并捕获任何次级断裂带或断层外变形。将从死亡谷-鱼湖谷断裂带确定的地质滑动速率与该地区其他断层的短期大地测量数据(年代际)和地质滑动速率进行比较，研究小组将能够评估在加州东部剪切带的莫哈韦段观察到的瞬时应变积累是作为太平洋-北美板块边界的基本特征向北延伸，还是与圣安德烈亚斯断裂的大弯曲相关的构造复杂性区域有关。研究小组将与美国国家公园管理局在死亡谷国家公园密切合作，向公园游客传播该项目的成果。

The degree to which fault loading and strain release rates are constant (or non-constant) in time and space is one of the most fundamental, unresolved issues in modern geodynamics. Comparisons of short-term geodetic data with very long-term (million year) global plate motion data indicate that, along most plate boundaries, strain storage and release are relatively continuous over a large temporal range. Recent comparisons of geodetic and geologic rate data across the Mojave section of the eastern California shear zone however, point to the occurrence of a pronounced strain transient. These observations raise several fundamentally important questions about how strain accumulates and is released along major plate boundary fault systems. A team of scientists from the University of Southern California, University of Cincinnati, and University of California at Berkeley seeks to understand the spatial and temporal constancy of strain accumulation and release in the northern half of the eastern California shear zone. Specifically, the work will focus on the Death Valley-Fish Lake Valley fault zone, the largest fault system in the region, extending over 300 km from the Garlock fault northward into southwest Nevada. Fault slip rates are being determined at a variety of geologic time scales (1,000 - 100,000 years) along the length of the fault system by dating offset alluvial landforms with cosmogenic nuclide and optically stimulated luminescence geochronology. Deformed geomorphic features are identified, mapped, and restored based on airborne laser swath mapping digital topographic data, acquired in a two-kilometer-wide swath along the fault to allow the research team to determine the geomorphic context of the fault zone and to capture any secondary fault strands or off-fault deformation. Comparison of geologic slip rates determined from the Death Valley-Fish Lake Valley fault zone with short-term geodetic data (decadal) and geologic slip rates from other faults in the region will allow the team to evaluate if the transient strain accumulation observed in the Mojave segment of the eastern California shear zone extends northward as a fundamental feature of the Pacific-North America plate boundary or is alternatively, tied to the zone of structural complexity associated with the Big Bend of the San Andreas fault. The research team will work closely with the U.S. National Park Service in Death Valley National Park to disseminate results of this project to park visitors.