Semblance filtering of airborne potential field data

Abstract

Airborne Gravity Gradiometer (AGG) data and Total Magnetic Intensity (TMI) data are acquired simultaneously by the BHP Billiton FALCONÔ system. An important step in the joint interpretation of AGG and TMI data is to identify and discriminate geological structures from the geophysical signatures in the data sets. Hence, the local similarity - or lack thereof - between the AGG and the TMI data is an important clue in the geological interpretation of the data. A spectral semblance filter computes the resemblance of the two data sets individually for each wave number in the Fourier domain. Spectral semblance filtering enables the interpreter to separate and isolate events that are coherent in two different data sets, such as gravity and magnetic. An example, using data from a FALCONÔ survey over the Hardey Syncline in the Hamersley Basin, demonstrates the use and the advantages of the spectral semblance filtering of airborne potential fields data.