Tectonic controls of Holocene erosion in a glaciated orogen

Byron Adams*, Todd Ehlers

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

2 Citations (Scopus)
228 Downloads (Pure)

Abstract

Recent work has highlighted a strong, worldwide, alpine glacial impact on orogen erosion rates over the last 2Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen: the Olympic Mountains, USA. We present 14 new 10Be and 26Al analyses which constrain Holocene erosion rates across the Olympic Mountains. Basin-averaged erosion rates scale with basin-averaged values of 5km local relief, channel steepness, and hillslope angle throughout the range, similar to observations from non-glaciated orogens. These erosion rates are not related to mean annual precipitation or the marked change in Pleistocene alpine glacier size across the range, implying that glacier modification of topography and modern precipitation parameters do not exert strong controls on these rates. Rather, we find that despite spatial variations in glacial modification of topography, patterns of recent erosion are similar to those from estimates of long-term tectonic rock uplift. This is consistent with a tectonic model where erosion and rock uplift patterns are controlled by the deformation of the Cascadia subduction zone.
Original languageEnglish
Pages (from-to)595-610
Number of pages16
JournalEarth Surface Dynamics
Volume6
Issue number3
Early online date26 Jul 2018
DOIs
Publication statusPublished - Sep 2018

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