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

该奖项全部或部分由2021年美国救援计划法案（公法117 - 2）资助。黄石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，该地区下方的黄石热点的通道被认为是通过抬升该地区的地形造成了更大规模的景观变化。该项目将通过量化蒙大拿州西南部加拉廷河在过去600多万年的侵蚀历史来测试这一理论。地幔动力学和地球表面之间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。加拉廷河从黄石高原流出，记录了黄石高原的地貌是如何随着黄石热点的到来而抬升、侵蚀和变化的。将使用对数万年至数百万年时间尺度上的侵蚀历史的定量估计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，目的是增加上大学和攻读技术学位的学生人数。该项目还支持在三个机构培训研究生和本科生，并帮助两名职业生涯初期的女教师晋升。该项目的总体目标是跟踪在蒙大拿州西南部的加拉廷河流域的切口，挖出来，和地形起伏的速度和演变过程中的方法和黄石热点在该地区的到来。排水系统的山区上部正在积极挖掘，而下部包含了中新世至更新世的沉积记录，最近正在切割。基岩低温热年代学将与盆地的碎屑热年代学和河流阶地的发光测年相结合，以创建跨时间尺度的切割和折返速度的完整记录。这些和其他地质观测将被整合到一个景观演变模型中，以测试该地区地表隆起模式和驱动因素的假设。研究内容包括：1）上加勒廷河流域白垩纪和始新世侵入岩河谷-山脊剖面的磷灰石（U-Th）/He和4He/3He热年代学，并结合地质约束条件，量化新生代剥露和地貌演化; 2）加勒廷河沿着剖面阶地的测绘和发光测年，以约束第四纪切割和变形; 3）碎屑磷灰石裂变径迹，U-Pb，和发光测年从中新世和第四纪沉积物在加拉廷山谷，以量化折返率在该时间跨度;和4）整合地质和年代学数据到一个数字景观演化模型，以测试假设和量化的幅度表面隆起使用反演方案。从高中到研究生的学生将直接参与这项研究，包括通过暑期实习计划，贫困高中学生将参与爱达荷州大学的研究。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.