The subcrustal lithosphere underlying the southern Archean Churchill Province (ACP) in western Canada is at Least one order of magnitude more electrically conductive than the Lithosphere beneath adjacent Paleoproterozoic crust. The measured electrical properties of the Lithosphere underlying most of the Paleoproterozoic crust can be explained by the conductivity of olivine. Mantle xenolith and geological mapping evidence indicate that the Lithosphere beneath the southern ACP was substantially modified as a result of being trapped between two nearly synchronous Paleoproterozoic subduction zones. Tectonically induced metasomatism thus may have enhanced the subcrustal Lithosphere conductivity of the southern ACP.