Cataclysmic erasure of mountain topography and major unrealized seismic hazards in the northern Basin and Range

这个多学科项目将调查与黄石火山热点有关的火山活动在多大程度上截断了落基山脉北部的高起伏山脉。随着时间的推移，热点向东北方向发展，它以比自然侵蚀过程快得多的速度“抹去”了先前存在的构造地形，并通过这样做，从根本上重塑了整个地区的地形、河流和气候演变。这项研究将集中在怀俄明州西北部的今天的南部提顿山脉，据推测，该山脉已经进一步向南延伸，随后被200万年后的黄石火山口喷发所移除。此外，该项目将解决新生断层与活跃迁移的黄石热点期间形成的地震活动之间的联系；因此，该项目有可能极大地加强对与提顿断层相关的潜在地震危险的了解。提顿和黄石每年吸引了700万游客，通过将这两个看似互不相关的地质特征联系起来，研究人员可以为公众提供一种新的方式来理解世界上最独特和最多样化的自然景观之一。这项研究的结果将被纳入新的公众意识运动和非正式的公共教育，包括游客中心展览、公共讲座以及开发一个网站和一系列迷你纪录片。该项目还将通过支持两名博士生的高级实地和实验室培训、多名本科生的研究培训和协作经验，促进预期的社会成果，重点是将代表性不足的少数群体纳入STEM教育。在项目的最后一年，所有成果将在一个研讨会上发布，该研讨会包括所有地区利益相关者，包括蒂顿县和杰克逊市代表、大学研究人员、国家公园管理局、美国地质调查局和美国开垦局。传统上，蒂顿正断层活动被解释为沿着山脉前缘和邻近的杰克逊山谷之间的地形断裂，这一点已被最近的激光雷达研究证实。普遍认为，断层必须始终存在于山脉前缘的地形断裂处附近，因此，断层北侧的滑动通常被解释为随着泰顿山脉北部地形的后退而减弱。然而，两个关键数据集表明，今天保存下来的残余地形可能没有反映提顿断层的北部范围，包括：记录长期断层滑动和山脉隆起历史的新数据表明，提顿断层最初可能比之前认为的向北延伸得更远；最近获得的激光雷达图像显示，多个候选断层陡峭可能代表提顿断层的活动北部范围。为了验证提顿山脉最初延伸到更北的假设，研究人员正在使用热年代学结合逆热历史和热运动学模型来进一步精炼提顿断层主段的滑动历史，并确定提顿断裂北部投影的可能长度。其次，研究人员将使用从杰克逊湖获得的高分辨率地震反射数据网格来确定主要的提顿断层与不同的断层陡峭是如何联系在一起的，这些断层陡峭显示出类似的现代偏移。这项调查还将使调查人员能够开发下盘和上盘取心靶标，其产品将与放射性碳地质年代学一起用于开发幕式断层滑移历史，该历史可与先前对拟议研究区域南部和北部其他断层段的沟槽研究相比较。将沿着主蒂顿断层、湖泊断层段和北段的滑动事件的时间联系起来，将使研究人员能够确定所有这些段是否在地震发生上都有联系。目前的断层滑动事件目录仅基于沟槽研究，但细粒湖泊沉积物很可能保存了更完整的孕震记录，从而为识别以前未发现的滑动事件提供了可能性。最后，调查人员将获得多条陆上断层-正常地震反射线，以证明提顿断层的北部延伸。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This multidisciplinary project will investigate the extent to which progression of volcanism associated with the Yellowstone hot spot has truncated high-relief mountain ranges of the northern Rocky Mountains. As the hotspot has progressed northeastward through time, it has “erased” preexisting tectonic topography at rates significantly faster than natural erosional processes and by doing so, fundamentally reshape the topographic, fluvial, and climatic evolution of an entire region. The research will focus on the present-day southern Teton Range in northwest Wyoming, which is hypothesized to have extended farther south and was subsequently removed by the post-2 million-year eruptions of the Yellowstone caldera. In addition, the project will address the link between nascent faults and seismic activity that have formed during the actively migrating Yellowstone hotspot; thus, this project has the potential to greatly enhance the understanding of potential seismic hazards associated with the Teton fault. The Tetons and Yellowstone attract 7,000,000 visitors annually and by linking these two seemingly unrelated geologic features the investigators can provide the public with a new way of understanding one of the most unique and diverse natural landscapes in the world. The results of this research will be incorporated into new public awareness campaigns and informal public education, including visitor center exhibits, public talks, and development of a website and a series of mini-documentaries. The project will also advance desired societal outcomes by supporting advanced field and laboratory training for two doctoral students, research training and collaboration experience for at multiple undergraduate students, with an emphasis on including underrepresented minorities in STEM education. In the final year of the project, all results will be disseminated at a workshop that includes all regional stakeholders, including Teton County and Jackson city representatives, university researchers, National Park Service, U.S. Geological Survey, and the U.S. Bureau of Reclamation.Traditionally, the active Teton normal fault is interpreted to follow the topographic break between the range front and the adjacent Jackson Valley and this has been confirmed by recent LiDAR studies. The commonly held belief is that the fault must always be present near the topographic break at the range front, and thus slip on the northern extent of the fault is often interpreted to diminish as the topography recedes in the northern Teton Range. However; two key datasets indicate that the relict topography preserved today may not reflect the northern extent of the Teton fault, including: new data documenting the long-term fault slip and range uplift history suggests that the Teton fault may have originally extended much farther north than previously thought; and, recently acquired LiDAR imagery reveals multiple candidate fault scarps that may represent the active northern extent of the Teton fault. To test the hypothesis that the Teton Range originally extended much farther north, the investigators are using thermochronology combined with inverse thermal history and thermal-kinematic modeling to further refine the slip history along the main segment of the Teton fault and determine the possible lengths of a northern Teton fault projection. Second, the researchers will use a grid of high-resolution seismic reflection data acquired from Jackson Lake to define how the main Teton fault links with disparate fault scarps that display similar modern offset. This survey will also allow the investigators to develop footwall and hanging wall coring targets, the products of which will be used with radiocarbon geochronology to develop an episodic fault slip history that can be compared with previous trenching studies of other fault segments both south and north of the proposed study area. Linking the timing of slip events along the main Teton fault, the lake fault segments, and the northern segments will allow the researchers to determine whether or not all of these segments are seismogenically linked. The current catalog of fault slip events is based solely on trenching studies, but it is likely that the fine-grained lake sediments preserve a more complete seismogenic record, thus providing the possibility for identifying slip events that have not been previously identified. Finally, the investigators will acquire multiple onshore fault-normal seismic reflection lines to demonstrate a northern extension of the Teton fault.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.