Mag 3D and Grav 3D

Magnetic and Gravity Inversion Software 
The MAG3D and GRAV3D programs were developed by the UBC–Geophysical Inversion Facility of the Department of Geophysics and Astronomy at the University of British Columbia. The forward model component calculates the magnetic value (or residual gravity value) at a point XYZ due to a regular 3 dimensional array of cells of varying magnetic susceptibility (or density).

The 3-D cell array is defaulted to zero susceptibility (or density) above the ground surface and below ground the susceptibility (density) values varies to reflect the geology. The inversion process identifies a susceptibility (density) value for each subsurface cell that together would produce a magnetic (gravity) value at each XYZ location that best approximates the measured magnetic (gravity) value.

Viewing tools allow one to view the distribution of susceptibility or density cells in a colour-coded 3D array. 

Mag 3D Example

The magnetic data in the above example is taken from Ontario Airborne Geophysical Dataset 1211 (originally flown by Spider Resources and KWG Resources in the mid 1990s).  In the subset above, three De Beers kimberlites can be easily spotted.   This data was processed using Mag3D and the resulting 3-dimensional grid is shown below.  The grid cells are colour-coded to modelled magnetic susceptibility.

Cells with extremely low susceptibility have been removed for this illustration and the surface has been shaved off at a depth of 70m.  The three shallow kimberlites are visible, and their cross-sections have been exposed.  A deeper linear basement feature is also visible.