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Imaging a paleovalley with passive seismic methods: Evidence for glacial carving of Unaweep Canyon (Colorado, US)
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  • Deepankar Dangwal,
  • Michael Behm,
  • Xiaowei Chen,
  • Gerilyn Soreghan
Deepankar Dangwal
University of Oklahoma Norman Campus

Corresponding Author:[email protected]

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Michael Behm
School of Geosciences, University of Oklahoma
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Xiaowei Chen
University of Oklahoma
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Gerilyn Soreghan
University of Oklahoma
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Abstract

High-resolution passive seismic imaging of shallow subsurface structures is often challenged by the scarcity of coherent body-wave energy in ambient noise recorded at surface stations. We show that autocorreleation (AC) of teleseismic P-wave coda extracted from just 1-month of continuous recording at 5 Hz geophones can overcome this limitation. We apply this method to investigate the longitudinal subsurface structure of Unaweep Canyon, a paleovalley in western Colorado (US) with complex evolution. Both fluvial and glacial processes have been proposed to explain the canyon’s genesis and morphology. The teleseismic P-wave coda AC retrieves zero-offset reflections from the shallow (200 – 500 m depth) basement interface at 120 stations along a 5 km long profile. Additionally, we invert interferometrically retrieved surface wave dispersion for the shear-wave structure of the sedimentary fill. Combined interpretation of these results and other geophysical and well data suggests an overdeepened basement geometry due to glacial processes.