Technical Papers - Airborne Magnetics

Automatic Conversion of Magnetic Data to Depth, Dip and Susceptibility Contrast Using the SPI^TM Method

Jeffrey B. Thurston and Richard Smith, Fugro Airborne Surveys
2060 Walkley Road, Ottawa, Ontario, Canada, K1G 3P5 

Abstract

The Source Parameter Imaging (SPI TM ) method computes source parameters from gridded magnetic data. The method assumes either a 2-D sloping contact or a 2-D dipping thin-sheet model and is based on the complex analytic signal. Solution grids show the edge locations, depths, dips, and susceptibility contrasts. The estimate of the depth is independent of the magnetic inclination, declination, dip, strike and any remanent magnetisation; however, the dip and the susceptibility estimates do assume that there is no remanent magnetisation. Image processing of the source-parameter grids enhances detail and provides maps that facilitate interpretation by non-specialists.

The SPI method tests successfully on synthetic profile and gridded data. SPI maps derived from aeromagnetic data acquired over the Peace River Arch area of northwestern Canada correlate well with known basement structure and furthermore show that the Ksituan Magmatic Arc can be divided into several susceptibility subdomains.

GEOPHYSICS, VOL. 62, NO. 3 (MAY-JUNE 1997); P. 807-813, 4 FIGS. Manuscript received by the Editor October 24, 1995; revised manuscript received August 28, 1996. © 1997 Society of Exploration Geophysicists. All rights reserved.