title: High-resolution lithosphere viscosity and dynamics revealed by magnetotelluric imaging.
abstract: An accurate viscosity structure is critical to truthfully modeling lithosphere dynamics. Here, we report an attempt to infer the effective lithospheric viscosity from a high-resolution magnetotelluric (MT) survey across the western United States. The high sensitivity of MT fields to the presence of electrically conductive fluids makes it a promising proxy for determining mechanical strength variations throughout the lithosphere. We demonstrate how a viscosity structure, approximated from electrical resistivity, results in a geodynamic model that successfully predicts short-wavelength surface topography, lithospheric deformation, and mantle upwelling beneath recent volcanism. We further show that this viscosity is physically consistent with and better constrained than that derived from laboratory-based rheology. We conclude that MT imaging provides a practical observational constraint for quantifying the dynamic evolution of the continental lithosphere.
authors.affiliation: Department of Geology, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA. ljliu@illinois.edu.
authors.forename: Lijun
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Earth Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors.forename: Derrick
authors.initials: D
authors.lastname: Hasterok