Rapid river incision across an inactive fault—Implications for patterns of erosion and deformation in the central Colorado Plateau

Joel Pederson, Neil Burnside, Zoe Shipton, Tammy Rittenour

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

The Colorado Plateau presents a contrast between deep and seemingly recent erosion and apparently only mild late Cenozoic tectonic activity. Researchers have recently proposed multiple sources of epeirogenic uplift and intriguing patterns of differential incision, yet little or no quantitative constraints exist in the heart of the plateau to test these ideas. Here, we use both optically stimulated luminescence (OSL) and uranium-series dating to delimit the record of fluvial strath terraces at Crystal Geyser in southeastern Utah, where the Little Grand Wash fault crosses the Green River in the broad Mancos Shale badlands of the central plateau. Results indicate there has been no deformation of terraces or surface rupture of the fault in the past 100 k.y. The Green River, on the other hand, has incised at a relatively rapid pace of 45 cm/k.y. (450 m/m.y.) over that same time, following a regional pattern of focused incision in the “bull’s-eye” of the central plateau. The Little Grand Wash fault may have initiated during Early Tertiary Laramide tectonism, but it contrasts with related structures of the ancestral Paradox Basin that are presently active due to salt dissolution and focused differential erosion. We also hypothesize there may be a Pliocene component of fault slip in the region linked to broad-wavelength erosional unloading, domal rebound, and extension. An apparent rapid decrease in incision rates just upstream through Desolation Canyon suggests the Green River here may have recently experienced an upstream-migrating wave of incision.
Original languageEnglish
Pages (from-to)513-520
Number of pages8
JournalLithosphere
Volume5
Issue number5
Early online date3 Sep 2013
DOIs
Publication statusPublished - 1 Oct 2013

Keywords

  • rapid river incision
  • inactive fault
  • central Colorado Plateau
  • patterns of erosion
  • deformation
  • absolute age
  • carbonate rocks
  • chronostratigraphy
  • geomorphology

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