Each geologic province has unique geological or geophysical parameters and therefore prospective gravity and magnetic signatures associated with each individual province will vary accordingly. Pattern recognition of anomaly signatures is of vital importance to all interpretation sciences. The following discussion is one of a series of six on the importance of pattern recognition. Basement is sometimes described as a mosaic of crystalline blocks at different depths with varying density and magnetization. The block depths, local structuring, and magnetic properties, together with an area’s location in the earth’s magnetic field, govern the local magnetic anomaly patterns. The block depths, density variations, and local structuring govern the gravity anomaly patterns. Variations in basement block density and magnetization are normally due to petrological differences but could also be due to variations in internal fracturing, crystal orientation, or magnetic remanence.
Geoscientists need to have a working knowledge of which types of anomaly patterns are important for the purpose of better integration of gravity and magnetic data with seismic and geological data to develop exploration targets. Using an integration process in exploration is known to reduce risk and evaluation time, thereby reducing the total cost of exploration.
In this module, density or density contrast units are expressed as gm/cc and magnetic susceptibility or susceptibility contrasts are expressed in micro-cgs units, sometimes abbreviated to cgs.