Collaborative Research: Exploring the tempo of exhumation and relief development to investigate mantle-to-surface connections around the Yellowstone hotspot

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。黄石公园是一个地幔热点在大陆下方上升的地区，导致火山活动和该地区标志性的地热特征。此外，黄石热点的通过可能通过抬升区域地形引起了更大范围的地貌变化。这个项目将通过量化过去600多万年来蒙大拿州西南部加拉丁河的侵蚀历史来检验这一理论。地幔动力学和地球表面之间的联系的性质和强度仍然是构造学领域的一个广泛问题，黄石公园是研究这些相互作用的理想地点。加拉丁河从黄石高原流出，记录了随着该地区黄石热点的到来，地貌是如何抬升、侵蚀和变化的。对数万至数百万年时间尺度上的侵蚀历史的定量估计将被用来检验关于哪些地球动力学过程有助于地形隆起的假设。该项目的结果将促进我们对黄石地区景观形成的理解，该地区每年接待数百万游客。此外，该项目还支持为来自爱达荷州的未得到充分服务的高中生提供地球科学实习机会，旨在增加进入大学并攻读技术学位的学生人数。该项目还支持对三个机构的研究生和本科生进行培训，并帮助促进两名职业生涯早期的女教员的职业生涯。该项目的总体目标是跟踪在蒙大拿州西南部的加拉丁河流域，在黄石热点接近和到达期间，切割、挖掘和地形起伏的速度和演变。多山的水系上部正在积极地折返，而下部则包含了这次折返的中新世至更新世的沉积记录，最近正在被切割。基岩低温热年代学将与来自盆地的碎屑热年代学和河流阶地的发光测年相结合，以创建跨越时间尺度的切割和挖掘速度的完整记录。这些和其他地质观测将被整合到一个地貌演变模型中，以检验该地区地表抬升模式和驱动因素的假说。研究内容包括：1)盖拉丁上游白垩纪和始新世侵入岩山谷到脊线的磷灰石(U-Th)/He和4He/3He热年代学，并结合地质约束条件量化新生代折返和地貌演化；2)盖拉丁河沿横断面的阶地填图和发光测年，以约束第四纪的切割和变形；3)盖拉丁河谷中新世和第四纪沉积的碎屑磷灰石裂变径迹、U-铅和发光年龄，以量化该时间段的折返速率；以及4)将地质和年代学数据整合到数字景观演化模型中，以验证假设和利用反演方案量化地表隆起的幅度。从高中到研究生水平的学生将直接参与这项研究，包括通过暑期实习计划，贫困高中生将参与爱达荷大学的研究。该奖项反映了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 award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Yellowstone is an area where a mantle hotspot upwells beneath the continent causing volcanism and the region’s iconic geothermal features. In addition, the passage of the Yellowstone hotspot beneath the area is suggested to have caused larger scale landscape change by uplifting the regional topography. This project will test that theory by quantifying the erosion history of the Gallatin River, southwest Montana, over the last 6+ million years. The nature and strength of connections between mantle dynamics and Earth’s surface remains a broad question within the field of tectonics, and Yellowstone is an ideal location to study these interactions. The Gallatin River drains off the Yellowstone Plateau and records how the landscape has uplifted, eroded, and changed in response to the arrival of the Yellowstone hotspot in the region. Quantitative estimates of the erosion history on the timescales of tens of thousands to millions of years will be used to test hypotheses about which geodynamic processes contributing to topographic uplift. Results from the project will advance our understanding of the formation of the landscape in the Yellowstone region, an area that receives millions of visitors each year. In addition, the project supports a geoscience internship for underserved high school students from Idaho aimed at increasing the number of students who attend college and pursue technical degrees. The project also supports the training of graduate and undergraduate students at three institutions and helps to advance the careers of two early-career women faculty members. The overall goal of this project is to track the rates and evolution of incision, exhumation, and topographic relief in the Gallatin River drainage basin in southwest Montana during the approach and arrival of the Yellowstone hotspot in the region. The mountainous upper portion of the drainage is actively exhuming, whereas the lower portion contains a Miocene to Pleistocene sedimentary record of this exhumation, which is recently being incised. Bedrock low temperature thermochronology will be combined with detrital thermochronology from the basin and luminescence dating of river terraces to create a complete record of the tempo of incision and exhumation across timescales. These and other geologic observations will be integrated into a landscape evolution model to test hypotheses for patterns and drivers of surface uplift in the region. Research components include: 1) Apatite (U-Th)/He and 4He/3He thermochronology on valley to ridge transects of Cretaceous and Eocene intrusive rocks in the upper Gallatin drainage and integration with geologic constraints to quantify Cenozoic exhumation and relief evolution; 2) Mapping and luminescence dating of terraces along the transect of the Gallatin River to constrain Quaternary incision and deformation; 3) Detrital apatite fission track, U-Pb, and luminescence dating from Miocene and Quaternary sediments in the Gallatin valley to quantify exhumation rates over that timespan; and 4) Integration of geologic and chronologic data into a numerical landscape evolution model to test hypotheses and quantify magnitudes of surface uplift using an inversion scheme. Students ranging from high school to graduate level will be directly involved in this research, including through a summer internship program where underprivileged high school students will participate in research at the University of Idaho.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.