An analysis of geophysical and geological data from the Iso/New Insco test site, Quebec, Canada

The MEGATEM^II system was flown over a site containing the Iso and New Insco deposits. The existing geological information for these sites was compiled and the MEGATEM response was found to be consistent with the geological information and previous geophysical information. The MEGATEM system was found to provide better information than the historical INPUT data. Height attenuation tests infer the MEGATEM system could see the Iso deposit if it were buried 230 m deep, whereas the INPUT could only see it if it were buried less than 60 m deep. A comparison of 90 and 30 Hz data shows that 30 Hz is better for discriminating the better conductors (e.g. New Insco), while 90 Hz sees the poorer conductors more clearly. A number of EM modeling packages were used to see if the known geology was consistent with the measured data. New Insco was determined to be something between a plate and a sphere (a thick prism). Iso was best modeled with multiple plates. The more conductive plates correspond to the more copper rich parts of the body and the less conductive parts to thinner, smaller zones. © 2005 Society of Exploration Geophysicists.