Magnetotelluric prospecting in the Matagami mining camp

In this thesis, 2D MT modeling program was modified to include a varying complex resistivity with frequency by implementing the Cole-Cole equation in the forward code. The code was validated with analytical solutions and some existing results to MT models with resistivity dispersion. Bodies with induced polarization (IP) effects were found to be detectable but only for bodies at depths less than their geometrical dimensions. The electrical and inductive properties (i.e. chargeability (m), time constant (tau) ...) of the body greatly influence the outcome of the MT response and the ability to be detected by the MT.;The capability of mapping structures in the Matagami mining camp was investigated by modelling and by interpretation of a very large existing MT survey. Strong presence of distortion and noises were found in the magnetotelluric (MT) survey data at the Matagami southern flank region. Various methods were used to quantify the dimensionality of the surveyed region as 2D/3D and 3D. 2D inversion was done parrallel and perpendicular to the determined strike direction. We have found the MT surveyed area to contain 2D medium size structures of mixed size, orientation and shape in a 3D medium. The inversion results were then interpolated to build a 3D model. 3D forward response was done to verify the fit of the 3D model responses with the survey data. The 3D model responses resemble the survey data. By adjusting the 1D earth crust model and by adding a static shift correction, it is possible to produce responses that better fit the survey data.