The Spectral Determination of Depths to Buried Magnetic Basement Rocks

The power spectrum of airborne magnetometer total intensity field profiles can be used to determine average depth values to buried magnetic rocks. These depths are established from the slope of the log-power spectrum at the lower end of the total wavenumber, or spatial frequency band. The method is based on the assumption that the magnetic effect of the basement surface can be simulated by an uncorrelated distribution of magnetic line sources, and is independent of the magnetic declination and inclination for straight-line profiles. Calculations carried out on profile data for an area in North-western Canada yielded good agreement with known basement depths.