Along-strike variations in active faulting in the northwest Himalaya with implications for the evolution of the Himalaya

喜马拉雅西北部活动断层的沿走向变化及其对喜马拉雅演化的影响

• 批准号: RGPIN-2014-04260
• 负责人: Morell, Kristin
• 金额: $ 1.89万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633772
• 关键词: Along; strike; variations; active; faulting

This research program will define the 3-D geometry of active faults across a portion of the northwestern Himalayan mountain range and evaluate how these faults have moved through time. It is these faults that accommodate the convergence associated with the collision of the Indian and Eurasian tectonic plates. The focus will be on a ~500 km long region astride the trans-Himalayan drainage divide between the Indus and Ganges river systems, where preliminary data indicate that there could be marked range-parallel changes in fault structure and associated landscape evolution. The research program will test for a regional westward decrease in total shortening, a measurement of the total amount of mountain building that has occurred due to the collision of the Indian and Eurasian tectonic plates. Historically, the active faults in the Himalaya have been difficult to identify because many of the faults that are seismically active are not exposed at the Earth’s surface and are also difficult to image. To overcome these challenges, this study will use a combination of proxies that together will identify the active faults and how they have evolved through time. These methods include: 1) analysis of the shape of river systems and how they are affected by faulting; 2) measurement of rates of erosion and unroofing across the landscape; and 3) cross section balancing that will provide estimates of total shortening. The research program will link these rates of erosion and shortening amounts to rock uplift caused by the active faulting, whether the faults intersect the Earth’s surface or not. This research program will provide significant advances in our understanding of how the entire Himalayan system has evolved, with relevance to seismology, geomorphology, tectonics and humankind in the region. The implications for the seismic cycle are particularly relevant given the region’s recognized seismic risk and dense population (> 10 million people). For instance, because earthquake magnitude is related to fault size, the geometry of active fault systems is important information in assessing where the largest earthquakes are likely to occur, and on which fault planes. Given the prediction that this region is overdue for large (and likely devastating) earthquakes, the region’s seismic potential has relevance to the many that inhabit the region and to India’s geopolitical partners, including Canada. An important aspect of the program will be to train Canadian students in the cutting-edge techniques that link geomorphology to active tectonics. Students will have the opportunity to gain such skills based on digital, laboratory and field datasets that they will be involved in collecting. The approach can be applied to understand the distribution of active deformation and seismic hazards in any actively deforming region on Earth, including the Cascadia subduction zone along the west coast of Canada.

这项研究计划将确定喜马拉雅山脉西北部一部分活动断层的三维几何形状，并评估这些断层如何随时间移动。正是这些断层适应了印度和欧亚构造板块碰撞所带来的汇聚。重点将放在横跨印度河和恒河水系之间跨喜马拉雅流域分水岭的约500公里长的区域，初步数据表明，断层结构和相关景观演变可能会发生明显的范围平行变化。该研究计划将测试区域向西减少的总缩短量，这是由于印度和欧亚构造板块碰撞而发生的造山总量的测量。从历史上看，喜马拉雅山的活动断层很难识别，因为许多地震活跃的断层并没有暴露在地球表面，也很难成像。为了克服这些挑战，本研究将使用多种代理的组合，这些代理将共同识别活动断层以及它们如何随着时间的推移而演变。这些方法包括：1）分析河流系统的形状以及它们如何受到断层的影响; 2）测量整个景观的侵蚀和去顶率; 3）横截面平衡，这将提供总缩短的估计。这项研究计划将把这些侵蚀率和缩短量与活动断层引起的岩石隆起联系起来，无论断层是否与地球表面相交。这项研究计划将为我们了解整个喜马拉雅系统如何演变提供重大进展，与该地区的地震学，地貌学，构造学和人类有关。考虑到该区域公认的地震风险和人口密集（超过1 000万人），这对地震周期的影响尤其重要。例如，由于地震震级与断层的大小有关，因此活动断层系统的几何形状是评估最大地震可能发生的地点和断层面的重要信息。考虑到该地区早该发生大地震（可能是毁灭性的）的预测，该地区的地震潜力与居住在该地区的许多人以及包括加拿大在内的印度地缘政治伙伴有关。该计划的一个重要方面将是培训加拿大学生掌握将地貌学与活动构造联系起来的尖端技术。学生将有机会根据他们将参与收集的数字，实验室和现场数据集获得这些技能。该方法可用于了解地球上任何活动变形区域的活动变形和地震灾害的分布，包括加拿大西海岸沿着的卡斯卡迪亚俯冲带。