The utility of potential field enhancements for remote predictive mapping

Abstract

Potential field (gravity and magnetic) data are fundamental to geologic mapping approaches based on geophysical interpretations. Lithologic and structural information can be extracted from amplitudes and trends of the gravity and magnetic anomalies. To assist in the interpretation, data enhancements are commonly used to transform the original data into new quantities that emphasize or suppress some specified component, resulting in a more easily interpreted representation. The number of available enhancements is rapidly increasing and begs the following question: Are they all useful and effective? Based on modelling, theoretical arguments, and real data examples, we evaluate 12 enhancements in terms of their effectiveness. Four of the 12 are found to be redundant, giving almost identical results when used for quantitatively mapping the edges of magnetic sources or, equivalently, geologic contacts. Two others produce similar levels of detail, so both enhancements are not needed. Two other enhancements are susceptible to noise in the data, leading to a lack of continuity in the mapped contact locations. One of the enhancements produces extra, false contact locations, which can complicate mapping, especially in areas of complex source distributions. When enhancements are used to derive images for qualitative interpretation, only two out of the four that are appropriate for this kind of interpretation give useful information.