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.

该研究项目将定义喜马拉雅山脉西北部部分活动断层的 3D 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与印度和欧亚构造碰撞相关的聚合。重点将放在横跨印度河和恒河系统之间跨喜马拉雅河流域的约 500 公里长的区域，初步数据表明，那里可能存在明显的范围平行。该研究项目将测试区域向西总缩短量的减少，这是历史上由于印度和欧亚板块碰撞而发生的造山总量的测量。喜马拉雅山的活动断层一直难以识别，因为许多地震活动断层并未暴露在地球表面，而且也难以成像。为了克服这些挑战，本研究将使用多种代理方法的组合。识别活动断层及其随时间的演变，这些方法包括：1）分析河流系统的形状以及断层对它们的影响；2）测量整个景观的侵蚀和剥落率；3）剖面平衡将提供总缩短的估计，该研究项目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，该研究项目都将在我们的研究中取得重大进展。理解考虑到该地区公认的地震风险和人口稠密（例如，人口超过 1000 万），整个喜马拉雅系统如何演化，以及该地区的地震学、地貌、构造和人类，对地震周期的影响尤其重要。 ，由于地震震级与断层大小有关，因此活动断层系统的几何形状对于评估可能发生最大地震的位置以及在哪个断层面上发生的预测是重要的信息，因为预测该地区早该发生大地震。 （并且可能是毁灭性的）地震，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与地貌学相关的尖端技术。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此类技能，该方法可用于了解任何活动中的活动变形和地震灾害的分布。地球上的变形区域，包括加拿大西海岸的卡斯卡迪亚俯冲带。