The Leibniz Institute for Applied Geophysics (LIAG), in cooperation with the Westphalian Wilhelms University of Münster (WWU Münster), has carried out another aerial survey for the exploration of ore deposits using the novel semi-airborne electromagnetics method in the joint project DESMEX II until the end of May 2022.
The method combines powerful dipole transmitters on the ground with newly developed, highly sensitive magnetic field sensors that are flown over a survey area in a drone-supported probe. For this purpose, LIAG deployed its high-current source and - together with the WWU Münster - a drone measurement system over an area of approximately 20 km2 in the district of Andalusia. Together with the project partners, aerial surveys have already been carried out in Germany (Schleiz, Kropfmühl, Gosetal, Bad Grund) using drones and helicopters. The data will now be analysed. Further flights in Namibia and Spain are currently being discussed.
Ground stations are also being installed to record the electric and magnetic fields along a profile. Additional ground measurements will verify the results of the new semi-airborne EM method. The measurement data over the complex subsurface will be made visible in a 3-D model. For this purpose, a new programme was developed for data processing due to the special specifics (strong topography, conduction mechanisms of the ore deposits). This allows the developed inversion algorithms to be used in addition to the aerial survey in Spain in order to be able to adequately interpret the measured data from Spain.
This altogether new procedure for the exploration of the subsurface, which is used in the context of the aerial surveys, was developed in the DESMEX project and funded by the Federal Ministry of Education and Research. The follow-up project DESMEX II is concerned with the practical implementation and further improvement of the sensor technology. For smaller-scale investigations, the use of a specially designed drone system is being tested as a cost-effective alternative, also for areas that are difficult to access.
In addition to the WWU Münster, which is coordinating the project, and the BGR, other scientific partners (University of Cologne, IPHT Jena) and industrial partners (Supracon AG, Imar Navigation, Terratec GmbH and DMT) are in the project network.
The drones will not only be used for raw material exploration, but also in the field of groundwater, e.g. the areal mapping of salt-freshwater transition zones - one of the core topics of the LIAG. On the other hand, in addition to the measurements with the LIAG drone system, algorithms for the cross-scale mapping of helicopter, drone and ground measurements are to be developed and applied to the measurement data obtained.