We have investigated the thermomechanical structure in strongly chaotic non-Newtonian thermal convection for both base-heated and internally-heated systems. Temperature can build up in stagnant regions and a non-Newtonian mantle can tolerate less internal-heating. Viscosity fields of strongly chaotic regime show a granular structure. The horizontal spectra of viscosity fluctuations obey a power-law and yield a fractal dimension of 1.6 to 1.8 for the isoviscosity lines, providing evidence for two-dimensional turbulence. Long wavelength viscosity variations are smoothed out by the turbulent non-Newtonian flows. ¿American Geophysical Union 1992