Derrick P. Hasterok

High-resolution lithosphere viscosity and dynamics revealed by magnetotelluric imaging

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.

Marine heat flow

John G. Sclater*, Derrick Hasterok, Bruno Goutorbe, John Hillier and Raquel Negrete Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA Department of Geosciences, University of Adelaide, Adelaide, Australia Instituto de Geosciencias, Universidade Federal Fluminense, Niteroi, Brazil Department of Geography, Loughborough University, Leicestershire, UK Departamento de Geologia, CICESE, Baja California, Mexico