Post-6 Ma Tectonic Evolution of the Bhutan Himalaya

不丹喜马拉雅山6 Ma后构造演化

• 批准号: 1049888
• 负责人: Kelin Whipple
• 金额: $ 18.78万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1049888&HistoricalAwards=false
• 关键词: Post; Ma; Tectonic; Evolution; Bhutan; Post; Ma; Tectonic; Evolution; Bhutan

Despite the considerable amount of research conducted in collisional mountain belts over the past few decades, little consensus has been reached regarding the influence that climatic and tectonic processes have on the surface, or how these processes are intertwined. Recent studies in the central Himalaya - a well studied, archetypal collisional mountain belt - have produced conflicting ideas regarding what is the most significant control on surface processes. Farther to the east, the Bhutan Himalaya have not been studied in much detail, but are often labeled as an outlier when compared to the classic Himalayan form and geology. However, the apparently anomalous features of Bhutan make it an excellent environment to test some of the outstanding hypotheses regarding the interplay of climate, tectonics and surface processes. Atypical high-elevation, but low-relief landscapes are perched above and surrounded by deeply incised canyons in the middle latitudes of Bhutan. This study explores the proposition that these landforms represent a pulse of erosion that is sweeping through Bhutan and progressively changing the relief. Such a pulse of erosion signals a change in either tectonics or climate, or both and the characteristics of transient landscapes, including especially patterns of erosion rate, provide a framework to determine what the drivers for the change are. This research project focuses on determining basin-averaged millennial-scale erosion rates from the concentration of cosmogenic radionuclides within river sands. The sampling strategy will cover a wide range of mean annual precipitation, river channel steepness and basin relief. By combining these erosion rates with constraints from low-temperature thermochronology data, the research team will be able to discriminate between climate and tectonic-driven models in Bhutan and test hypotheses regarding the relationships between climate, erosion rate, topography and tectonics that carry implications well beyond the Bhutan field site.The active nature of the problem addressed in this research has ramifications for many societal concerns including: seismic hazards, landslide hazards, sedimentation, reservoir management, navigability, soil erosion, and response to climate change. These issues are at times painfully clear to those who live in or near active mountain ranges throughout the world. Bhutan, because of its complicated political history and access issues, is one of the most poorly understood regions of the Himalaya. The research team is working closely with the National Environmental Commission of Bhutan to share findings in a meaningful way that better informs decisions in land use management and hazard mitigation. In addition, this research tackles fundamental problems in the understanding of mountain building. Many of the classic models of mountain building in collisional settings make predictions about the relative timing of fault activity; however, these assumptions have been shown to fail in some areas. The broad sample collection scheme will allow examination of uplift patterns across Bhutan to determine if these classic models hold true. Very little is known about the history of fault activity in Bhutan and therefore, any information regarding the pattern of uplift is invaluable to the governing bodies of Bhutan, who determine hazard assessment and control building codes.

尽管在过去几十年中，在碰撞山带进行了大量研究，但就气候和构造过程对地表的影响或这些过程如何交织而言，几乎没有达成共识。最近在喜马拉雅河中部的研究 - 一项经过良好研究的原型碰撞山带 - 对表面过程中最重要的控制是什么是矛盾的想法。在东方更远的地方，不丹喜马拉雅山尚未进行详细研究，但与经典的喜马拉雅形态和地质学相比，经常被标记为异常值。但是，不丹的明显异常特征使其成为一个很好的环境，可以测试有关气候，构造和表面过程相互作用的一些出色假设。非典型的高海拔，但低浮雕的景观栖息在不丹的中纬度上的峡谷上方和包围。这项研究探讨了这些地形代表侵蚀脉冲的主张，该腐蚀正在通过不丹扫荡并逐渐改变救济。这种侵蚀的脉冲信号标志着构造或气候的变化，或两者兼而有之，以及瞬态景观的特征，包括尤其是侵蚀率的模式，提供了一个框架，以确定变化的驱动因素是什么。该研究项目的重点是确定盆地平均千年尺度侵蚀率，从河沙中的宇宙源性放射性核素的浓度来确定。采样策略将涵盖广泛的年度降水，河道陡度和盆地浮雕。通过将这些侵蚀率与低温热量学数据的限制相结合，研究团队将能够区分不丹的气候和构造驱动的模型，以及关于气候，侵蚀率，地形和构造学之间的关系的关系，这些涉及到范围内的社会范围。危害，滑坡危害，沉积，水库管理，可通道，土壤侵蚀以及对气候变化的反应。这些问题有时对于生活在世界各地或附近的山脉附近或附近的人来说是痛苦的。不丹由于其复杂的政治历史和访问问题，是喜马拉雅山最了解的地区之一。研究小组正在与不丹国家环境委员会紧密合作，以有意义的方式分享发现，以更好地为土地使用管理和缓解危害的决策提供了信息。此外，这项研究解决了对山区建筑的理解的基本问题。碰撞环境中山区建筑的许多经典模型都可以预测断层活动的相对时机。但是，这些假设已显示在某些领域失败。广泛的样本收集方案将允许检查不丹各地的隆升模式，以确定这些经典模型是否成立。关于不丹的故障活动的历史知之甚少，因此，有关隆重模式的任何信息对于不丹的理事机构来说都是无价的，后者确定危害评估和控制建筑物代码。