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Constraining the Uplift of the Southeastern Sierra Nevada, CA using Multi-Mineral Detrital Thermochronology from Active Catchments
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  • Jacqueline Giblin,
  • Kip Hodges,
  • Kerry Gallagher,
  • Alexandra Horne
Jacqueline Giblin
Arizona State University

Corresponding Author:[email protected]

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Kip Hodges
Arizona State University
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Kerry Gallagher
University of Rennes
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Alexandra Horne
ADM Associates, Inc.
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Most thermochronological studies aimed at constraining exhumation rates rely on bedrock datasets. Often, they involve the analysis of samples collected along an elevation profile in terrains with high relief. However, there are several limitations to this approach, most importantly access to an appropriately steep traverse and sufficient relief to overcome uncertainties, and to have a broad enough range in closure ages as a function of elevation. Detrital thermochronology offers an alternative approach which can mitigate these challenges through coordinated dating of modern river sediments using multiple thermochronologic methods. Modern detrital sediments from active catchments provide an excellent source of material, typically rich in rock-forming and accessory minerals. Detrital thermochronologic data for material in sedimentary basins has been used widely to infer exhumation histories of sedimentary source terrains, reconstruct paleorelief, and evaluate spatial and temporal variations in erosion rates; however, there have been comparably fewer studies that apply this technique to evaluate regional exhumation patterns using detrital samples from active catchments. Based on the approach presented in Gallagher and Parra, (2020), we are exploring the capability of detrital thermochronologic data to infer regional exhumation patterns in the southeastern Sierra Nevada, CA. Here the uplift history remains debated and the potential mechanism of uplift has yet to be thoroughly constrained. Many catchments along the eastern side of the Sierra Nevada exhibit advantageous characteristics for detrital thermochronologic studies, including steep topography and high relief (that make it more difficult to sample bedrock), limited lithologic variability (which minimizes point-source biasing), relatively simple geologic structure, and relatively easy access to detrital sampling localities. Additionally, the dominant source of the southeastern Sierra Nevada catchments, the igneous units of the Sierra Nevada batholith, include abundant rock-forming minerals for 40Ar/39Ar thermochronology (hornblende, biotite, and sometimes muscovite) as well as abundant accessory minerals for (U-Th)/Pb geochronology(zircon), (U-Th)/Pb thermochronology (apatite), and (U-Th)/He thermochronology (zircon and apatite). Collectively, detrital thermochronological data from these minerals can elucidate much of the post-crystallization thermal history of the eastern flank of the Sierra Nevada. Preliminary results of this technique demonstrate the potential of this cost- and labor-efficient approach for exhumation history studies.