The influence of glacial topography on fluvial efficiency in the Teton Range, Wyoming (USA)

Sarah E. Johnson, Meredith L. Swallom, Ryan Thigpen, Michael McGlue, Jason M. Dortch, Sean Gallen, Edward Woolery, Kevin M. Yeager

Research output: Contribution to journalArticlepeer-review

Abstract

This study examines the role of topography as a dynamic boundary condition that limits the efficiency of fluvial erosion in the post-glacial Teton Range landscape. The volume of sediment currently stored in two major catchments was estimated using high-resolution LiDAR and geometric reconstructions of depth to bedrock. Seismic reflection data in Moran Bay reveals post-glacial sediment preserved behind a submerged moraine, which isolates the bay from the larger Jackson Lake depocenter. The volume of post-glacial sediment stored in the canyons and bay totals 173.82 ± 19.5336.0 (×10−3 km3), which translates to a catchment-wide sediment production rate of 0.17 ± 0.02 mm/yr. The rock-equivalent sediment volume in Moran Bay is 4.4 ± 0.9 (×10−3 km3), only ∼2.6% of the total post-glacial volume. While the estimated sediment production rate in the canyons is similar to the uplift rate, the denudation rate derived from Moran Bay sediment is 0.004 ± 0.001 mm/yr, implying highly inefficient post-glacial sediment transport. The fluvial system has been disequilibrated by glacial erosion such that interglacial valley profiles lack the steepness needed to transport sediment, delaying sediment evacuation until the next glacial advance, or until uplift sufficiently steepens the fluvial system so that it regains efficiency. Furthermore, colluvial production rates in the deglaciated valleys are close to long-term denudation and uplift rates, suggesting that once topography has been equilibrated to glacial erosion processes, subsequent glaciers do not need to produce much bedrock erosion, but mainly sweep out accumulated sediment to maintain equilibrium.

Original languageEnglish
Article number117643
JournalEarth and Planetary Science Letters
Volume592
DOIs
StatePublished - Aug 15 2022

Bibliographical note

Funding Information:
This work was supported by a UW-NPS seed grant and NSF-EAR 1932808 , the Overcash Field Fund at UK, and UK student research grants. We would also like to acknowledge Cooper Cearly, Ryan Goldsby, Autumn Helfrich, Hillary Johnson, and Giliane Rasbold for their work in the field. Comments from two anonymous reviewers greatly improved an earlier version of this manuscript.

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Teton Range
  • denudation
  • erosion rates
  • landscape evolution
  • post-glacial fluvial erosion
  • sediment budget

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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