T294 Physical and Numerical Modeling of Geologic Processes

Wednesday, 28 September 2016
8:00 AM - 12:00 PM
Mile High Ballroom 3B

HIGH-RESOLUTION LITHOSPHERE VISCOSITY AND DYNAMICS REVEALED BY MAGNETOTELLURIC IMAGING

Paper number: T294-7
Program: Technical Sessions
Time: 9:30 AM – 9:45 AM

Authors

  • Lijun Liu Presenting Author
    University of Illinois at Urbana-Champaign, Champaign, IL
  • Derrick Hasterok
    University of Illinois at Urbana-Champaign, Champaign, IL

Abstract

An uncertain viscosity structure is a major impediment to correctly modeling the behavior and evolution of the lithosphere. This problem is particularly acute at the sub-100 km scale where active deformation and volcanism occur. Here we report an attempt to infer the effective lithospheric viscosity from a high-resolution magnetotelluric (MT) survey across the western United States. The increased sensitivity of MT fields to the presence of electrically conductive fault-occupying fluids makes it a promising proxy for dictating small-scale variations in the mechanical strength of the lithosphere. We demonstrate how a viscosity structure, approximated from electrical resistivity, results in a geodynamic model that successfully predicts short-wavelength topography, deformation across the Basin & Range province, and localized mantle upwelling beneath a region of late Cenozoic volcanism. Comparison with observations suggests that MT imaging provides a powerful constraint on both the net strength and lateral variation of lithospheric viscosity. We propose that MT imaging represents a novel observational constraint for revealing the dynamic evolution of the crust and upper mantle.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-285452

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