Magnetotelluric Imaging of Precambrian Lithosphere Beneath Southern Alberta

Magnetotelluric (MT) data were collected at 67 stations during the 2008, 2009, and 2010 field seasons in southern Alberta. These have been combined with more than 300 MT stations previously collected in Alberta, allowing a three dimensional electrical resistivity model of the lithosphere to be developed to depths of 250 km. Initial modelling attempts of the MT data in southern Alberta showed that two dimensional data analysis could not be used to model these data. Therefore this study was undertaken to determine a three dimensional model that fits the data.;The resulting 3-D resistivity model has shown a regionally pervasive conductor in the upper mantle below the Loverna Block, coincident with a north dipping reflector. A similar regional conductor and north dipping reflector occurs below part of the Medicine Hat Block, further characterizing the Precambrian subduction zones below southern Alberta.