AEROMAGNETIC TECHNIQUES FOR MAPPING BASEMENT STRUCTURE - ADVANTAGES AND DISADVANTAGES OF 6 DIFFERENT TYPES OF DATA DISPLAYS

The existence of the Precambrian basement fault block pattern and its influence on later geology has been proven, demonstrated, and discussed by innumerable geologists and geophysicists and is no longer a matter of contention. Yet many geologists are untrained in the application of aeromagnetic maps which are used to define basement faults/shear zones in covered areas. To remedy this, the author has prepared the present tutorial on aeromagnetic map displays. In covered areas, i.e. areas covered with a sedimentary rock sequence, can be found some of the best understood structural geology on earth, that is, areas of petroleum exploration that have a high density of petroleum wells and seismic data available. Therefore, it is extremely illustrative to compare such areas of detailed geology with the locations of basement faults defined by magnetic maps. I will first show a comparison of a magnetic total intensity map and a profile residual map to illustrate the differences between raw and enhanced magnetic data. Then six different types of displays of enhanced data will be shown as follows:

1. “3D” perspective map 2. Color banded map 3. Ordinary contour map 4. Shade relief map 5. Black and white banded map 6. Stereo 3D map.

The displays are listed in increasing order of usefulness for mapping basement, and their relative advantages and disadvantages will be discussed.