Terracing potential field data

Abstract

Terracing (Cordell and McCafferty, 1989, Philips, 1992) is an operator that is applied to potential field data to produce regions of constant field amplitude that are separated by sharp boundaries. Magnetic data are usually transformed into pseudogravity data (Baranov, 1957) prior to the application of terracing. The objective of terracing is 'to recast potential field maps into a geologic map like format' (Cordell and McCafferty, 1989). Terracing is performed by moving a window through the data and computing the curvature at each point. The curvature of the field f is calculated using a three coefficient numerical approximation to the Laplacian derivative operator. The output value (located at the centre of the window) takes on one of two possible values. If the curvature is positive then the output value is set to the minimum of the data values in the window, while if it is negative then the output value is set to the maximum of the data values in the window. Terracing is performed in an iterative manner, with the data being sharpened progressively.