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Deciphering topographic signals of glaciation and rock uplift in an active orogen: a case study from the Olympic Mountains, USA

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Original languageEnglish
Number of pages13
JournalEarth Surface Processes and Landforms
Early online date8 Mar 2017
DOIs
DateAccepted/In press - 26 Jan 2017
DateE-pub ahead of print (current) - 8 Mar 2017

Abstract

Estimating recent patterns of erosion and rock uplift within Cenozoic orogens has proven difficult as signals of these processes have been obfuscated by Plio-Pleistocene glaciation. The topography of many mountain ranges integrates the effects of long-lived rock uplift, Late-Cenozoic climate variation, and post-glacial landscape adjustment. In this study, we employ a suite of topographic analyses to study the relief of an active mountain range on a sub-catchment scale in an effort to the separate the long-term signal of rock uplift from perturbations due to shorter-lived climate signals. We focus on the Olympic Mountains, USA, where patterns of exhumation and glaciation have been previously estimated; however, our methods and results are broadly applicable to other orogens.

Our analysis shows that Plio-Pleistocene alpine glaciers and the Cordilleran Ice Sheet have reduced the elevations of channel profiles and created anomalously low channel relief in the Olympic Mountains. Large low-gradient areas formed at lower elevations where ice sheets were present and alpine glaciers widened and deepened valleys. In the more rugged core of the range, near-threshold hillslopes along the margins of the oversteepened glacially-carved valleys, dominate the range. This implies a strong Plio-Pleistocene glacial climate control on the topography over the more recent evolution of the Olympic Mountains. However, the broad relief structure of the range appears to still record the regional rock uplift pattern and is suggestive of an east-plunging antiform, consistent with folding of the subducting plate or underplating of accreted rocks.

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    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Wiley at http://onlinelibrary.wiley.com/doi/10.1002/esp.4120/full. Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 22 MB, PDF document

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  • Supplementary information PDF

    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Wiley at http://onlinelibrary.wiley.com/doi/10.1002/esp.4120/full. Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 6 MB, PDF document

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