Collaborative Research: Geological Investigations of Non-Andersonian Conjugate Strike-slip Faults in Central Tibet

合作研究：西藏中部非安德森共轭走滑断层地质调查

• 批准号: 0911740
• 负责人: An Yin
• 金额: $ 14.88万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911740&HistoricalAwards=false
• 关键词: Collaborative; Research; Geological; Investigations; Non

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).A foundation of Earth Sciences is the ability to relate spatial arrangements of geologic features such as tectonic plate boundaries, earthquake-related ruptures, mountain uplifts and fault patterns in general to their causative forces. In this regard, geoscientists have long used the experimentally established Coulomb fracture criterion, which predicts certain angular relationships between faults, to explain the dynamic causes of fault formation. This approach has faced increasing difficulties as more and systematic observations show that many natural faults defy these angular relationships. This research will involve the use of a new experimental apparatus to simulate natural faulting, as well as an examination of the geometric evolution of large fault systems in central Tibet, to determine if a mechanical principle different to the Coulomb criterion is needed to explain the geometry of natural faults. Our ability to interpret lithospheric deformation, and perhaps more importantly the coupling between the flowing middle and fracturing upper crust, depends critically on the knowledge that relates observed fault geometries to causative dynamic conditions. The most commonly used relationship in this regard is the Coulomb fracture criterion that predicts X-shaped conjugate faults oriented at ~30° from the maximum compressive-stress direction. In nature, X-shaped conjugate fault geometries in strike-slip systems are rarely observed, and while fault geometries can be complex and difficult to interpret due to post-faulting deformation, V-shaped geometries with faults orientated at 60-75º from sigma one have been essentially overlooked. These V-shaped fault systems are common in nature with prominent large-scale examples in the Alpine-Himalayan collision zone. These investigators will test whether V-shaped conjugate faults in central Tibet were created by vertical-axis rotation or paired-general-shear flow by performing structural mapping and paleomagnetic analysis. The results and associated models should have important implications for whether the large-scale deformation of continents is fundamentally plate-like or fluid-like over geologic timescales.

该奖项是根据2009年的《美国复苏与再投资法》（公法111-5）资助的。地球科学的基础是与地质特征相关的空间安排，例如构造板块边界，与地震相关的破裂，山地升高，山地升高和一般对关键部队的断层模式。在这方面，地球科学家长期以来一直使用实验建立的库仑断裂标准，该标准可以预测断层之间的某些角度关系，以解释故障形成的动态原因。随着越来越多的系统观察表明，许多自然断层违背了这些角度关系，这种方法面临着越来越多的困难。这项研究将涉及使用新的实验设备来模拟自然断层，并检查中央西藏中部大断层系统的几何演化，以确定是否需要与库仑标准不同的机械原理来解释自然断层的几何形状。我们解释岩石圈变形的能力，更重要的是，流动的中层和破裂的上皮之间的耦合取决于将观察到的断层几何形状与严重的动态条件相关的知识。在这方面，最常用的关系是库仑断裂标准，该标准可预测X形偶联断层，从最大压缩应力方向〜30°定向。在本质上，很少观察到滑滑系统中的X形共轭断层几何形状，尽管由于后托架变形后，故障几何形状可能是复杂的，难以解释，但V形的几何形状在Sigma中以60-75º的断层为导向。这些V形断层系统在本质上是常见的，在高山 - 希马拉亚碰撞区域中具有显着的大规模示例。这些研究者将通过进行结构映射和古磁分析来测试中央西藏中的V形共轭断层。结果和相关的模型对于持续的大规模变形是从根本上类似板块还是类似于地质时间的时间尺度上的大规模变形。