New airborne methods and procedures for the exploration of mineral resources – An overview of BGR activities

Airborne geophysics is well established in the field of exploration of mineral deposits. Most of the methods applied in this respect are mandatory in order to define an exploration target in the subsurface i.e. airborne magnetics and electromagnetics. At present, BGR is involved in different aspects of airborne exploration of mineral resources, namely in the projects E3, DESMEX and HYPGEO. The E3-project targets a granite body containing mainly zinc and tin, surveyed by a combination of airborne frequency electromagnetics, total field magnetics and SQUID-based gradient magnetometry. The combination of these data sets reveals different physical properties of prominent geological structures. HYPGEO aims for a different sort of sensor combination. Here, high resolution hyperspectral camera systems are combined with gamma-ray spectrometry and again SQUID-based gradient magnetometry. The system will be tested over open pit mining areas in Germany and Spain, characterising surface structures by a combination of hyperspectral plus radiometric data and following depth structures via the mapping of the magnetic field gradient. Whereas all described methods focus on the surface or near-surface structures of mineral deposits, DESMEX is designed to explore depths down to one kilometre. For this purpose, we develop two competing systems, an audio frequency magnetics (AFMAG) system based on conventional induction coil and fluxgate systems and a SQUID-based sensing instrument.