Sheets modelling

The primary geophysical method used by mineral exploration companies active in Greenland is the airborne frequency domain electromagnetic method. Time-domain electromagnetic measurements have been utilized on Greenland by the Geological Survey of Denmark and Greenland (GEUS) and to a lesser extent by exploration companies.

Modeling and interpretation of both data types by utilization of multi-dimensional models are still severely restricted by excessive computer time and difficult to use algorithms. Therefore, simplifications are needed when large amounts of data are to be interpreted. As a consequence, modeling of mineralized zones is mainly done using thin, conductive sheets in a resistive host rock. Although the geometry is fairly simple, the model is often a reasonable approximation to the actual structure.

Related projects at the HydroGeophysics Group (HGG, University of Aarhus) has shown that it is indeed possible to develop a state of the art numerical code approximating mineralizations with thin sheets and carry out full scale data inversions including modeling of the entire measurement platform. The benefit is obviously better and more accurate determination of the geometry of the often complex mineralized zones which at the end decreases the risk of making “dry” boreholes or even overlook possible mineralizations.

The new algorithm can also be used for design studies in the sense that optimal data coverage can be estimated and optimal airborne platform determined.

In order to make the algorithm operational for real field data it is the intention to develop a system for data handling and visualization of the output. A natural choice of platform is the Aarhus Workbench which is developed and maintained by HGG, but compatibility with the AMIRA software package also in use at GEUS is also required.