An improved method for geological boundary detection of potential field anomalies

Abstract

Potential field methods such as gravity and magnetic methods are among the most applied geophysical methods in mineral exploration. A high-resolution technique is developed to image geologic boundaries such as contacts and faults. Potential field derivatives are the basis of many interpretation techniques. In boundary detection, the analytic signal quantity is defined by combining the values of horizontal and vertical derivatives. The outlines of the geologic boundaries can be determined by tracing the maximum amplitudes of analytic signal. However, due to superposition effects, in some cases that a variety of sources are adjacent, the detected boundaries are blurred. To overcome this problem, this study used enhanced analytic signal composed of the nth- order vertical derivative of analytic signal. The locations of its maximum amplitudes are independent of magnetization direction and geomagnetic parameters. This technique is particularly suitable when interference effects are considerable and when remanent magnetization is not negligible. In this paper this technique has been applied to gravity data of southwest England. Using this method, five granites outcrops and their separating faults are enhanced accurately.