MAGNETOTELLURIC MEASUREMENTS IN AN AREA OF WEST-CENTRAL ALBERTA WHEREDEEP ELECTRICAL-CONDUCTIVITY AND BASIN SEDIMENT GEOTHERMAL ANOMALIES COINCIDE

A magnetotelluric survey in the frequency range of approximately 0.01- 130 Hz was conducted in west-central Alberta, Canada, in an area where a deep electrical conductivity anomaly, discovered from geomagnetic d epth sounding studies, coincides with a geothermal gradient anomaly in the basin sediments. One-dimensional Fischer inversions of the determ inant invariants at each site were used to construct resistivity cross -sections for a number of profiles. The results indicate that a number of low-resistivity zones exists in the sediments. These zones appear to be associated with saline fluids which may have moved upward along faults and fractures from the southwest and transported heat to produc e the thermal anomaly and probably also carried hydrocarbons into the area. There is also evidence of a deeper low-resistivity zone (compare d with the basement resistivity values in the rest of central Alberta) that appears to extend to depth and may be related to the depth sound ing anomaly. It is unlikely that this conductive zone contributes subs tantially to the local geothermal anomaly in the upper sediments, but it may contribute to the slightly higher than normal heat flow in the area as a whole.