Exploring the Early History of the South Tibetan Fault System in Bhutan

探索不丹藏南断层系的早期历史

• 批准号: 0838112
• 负责人: Kip Hodges
• 金额: $ 27.97万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838112&HistoricalAwards=false
• 关键词: Exploring; Early; History; South; Tibetan

This research focuses on the South Tibetan fault system, one of the most enigmatic tectonic features of the Himalaya, and one that stirs much controversy in the Tectonics community. The South Tibetan fault system appears to be unique in that its kinematics are those of a low-angle, normal fault system while all other Himalayan fault systems with comparable displacements (many 10s to 100s of kilometers) have the more predictable kinematics of thrust fault systems typically found in mountain belts. The very existence of a feature like the South Tibetan fault system is indicating something fundamental about how the Himalaya, and mountain ranges in general, evolve. The PI and his colleagues work to clarify this message through their research. Unfortunately, in many parts of the Himalaya, the early history of the South Tibetan fault system has been obscured by late-stage deformation. This is not the case in Bhutan, where the PI and others have identified erosional remnants of early faults of the system that have been relatively undisturbed by younger deformation. This proposal describes targeted studies of these remnants. A broad array of techniques will be used to probe the early history of the fault system using these rare exposures. They include geologic mapping and structural analysis; quantitative element-partitioning thermobarometry; 40Ar/39Ar and (U-Th)/He thermochronology; and laser-ablation (U-Th)/Pb geochronology. Because the Himalaya and Tibetan Plateau are still evolving, studies of this natural laboratory provide critical information regarding the role that mountainous regions play in earth system function. For example, we know that the physiography of the Tibetan Plateau defines the weather patterns of the Asian monsoon climate, and this climate is the enabling mechanism for agriculture that feeds roughly 60% of the people on Earth. By detailing the processes that led to the establishment of the modern-day Himalaya and Tibetan Plateau, studies such as the one proposed here inform more effective strategies for the co-evolution of human societies and mountain landscapes.

这项研究的重点是南藏断层系统，这是喜马拉雅山中最神秘的构造特征之一，以及在构造社区中引起了很多争议。南藏断层系统似乎是独一无二的，因为它的运动学是一个低角度，正常断层系统的运动学系统，而所有其他具有可比位移（许多10至100 s公里）的喜马拉雅断层系统具有更可预测的推力故障系统的动力学通常在山带中发现。像南藏族断层系统这样的功能的存在表明，喜马拉雅山和山区的一般范围是如何发展的。 PI和他的同事通过他们的研究来阐明这一信息。不幸的是，在喜马拉雅山的许多地方，南藏断层系统的早期历史被后期变形所掩盖。在不丹，情况并非如此，那里的PI和其他人已经确定了系统早期断层的侵蚀残留物，而这些残余物被年轻的变形相对不受干扰。该提案描述了对这些残留物的有针对性研究。大量的技术将使用这些罕见的暴露量来探测断层系统的早期历史。它们包括地质图和结构分析；定量元素分配热压法； 40AR/39AR和（u-th）/HE热量学；和激光燃烧（U-TH）/PB地质学。由于喜马拉雅山和藏族高原仍在不断发展，因此对这项自然实验室的研究提供了有关山区在地球系统功能中扮演的作用的关键信息。例如，我们知道，藏族高原的生理学定义了亚洲季风气候的天气模式，这种气候是农业的有效机制，可为地球上大约60％的人提供。通过详细介绍导致现代喜马拉雅山和藏族高原建立的过程，诸如此处提出的研究为人类社会和山景共同发展提供了更有效的策略。