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ePaper created 2014-04-30, 16:22:09 | version 1.30.01
FOCUS// The HZDR Research Magazine WWW.Hzdr.DE 20 21 The Sikorsky helicopter took off on its first data acquisition flight over the Ore Mountains of Germany (Erzgebirge) on 22 October, 2013. In the meantime, it has now covered the core area of Geyer Forest. It is expected to be there again during the next two years, but with new measurement techniques on board that the experts of BGR want to test. These techniques should enable mineral resources to be found at depths of up to 500 meters; during the first flight, the measurements were only able to penetrate to a depth of 150 meters. Even though the airborne probe is flown about 30 to 40 meters above the ground, you cannot see the distinctive helicopter from the ground very often. It flies over the area keeping distances of 300 to 500 meters, following pre-determined flight lines. The BGR experts record countless data points. Nevertheless, they cannot draw definite conclusions about specific ore bodies. "You would have to go back and drill the identified target areas. Only these drill cores give exact insight as to which minerals in what quantities are present," according to Gutzmer. A further challenge: the researchers want to know exactly where the valuable resources are located in the subsurface. The airborne data by themselves are insufficient for this. Only the extent of the ore body can be determined from them. Additional measurement techniques are therefore needed. Seismic waves in the ground These techniques come from the Institute for Geophysics and Geoinformatics of the TU Bergakademie Freiberg. The researchers drop small weights on the ground there and set off small explosions similar to fireworks in order to create seismic waves in the ground. These are recorded by highly sensitive geophones. Since the individual strata in the subsurface reflect the seismic waves differently, the scientists can draw inferences about the subterranean formations this way. "The waves we create have a much lower signal level than signals created when the wind blows through the trees," says research associate Olaf Hellwig. The investigations therefore have as little impact on the environment as measurements by helicopter. In addition, the plan is that researchers from the University will take over another important task in the project: all of the information collected is to be incorporated into a high- resolution spatial model of the Geyer Forest subsurface. The scientists already have experience with this type of mathematical modeling for areas in northern Germany, but the Ore Mountains are considerably more complex in architecture according to Hellwig’s colleague, Mathias Scheunert. The experts of the Helmholtz Institute in Freiberg, the BGR, as well as those from the University all hope to present their findings publicly three years from now. It is conceivable that industry will be interested also. "First we have to await the investigations, especially those of the helicopter," says Gutzmer from HIF. "Then we can provide an informed assessment of the resource potential of the area. But the interaction of our proven low-impact methodology is just as important; it could be employed elsewhere for detection of mineral resources." ELECTROMAGNETICS IN THE AIR: Diagram depicting a helicopter and flight probe Contact _Helmholtz Institute Freiberg for Resource Technology at HZDR Prof. Jens Gutzmer j.gutzmer@hzdr.de