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

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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.