Near-Mine Exploration for Iron Ore at Malmberget Using Body-Wave Seismic Interferometry

Summary Since early days definition and targeting of ore bodies at Malmberget have been done with success by geophysical methods by way of ground gravimetric and geomagnetic exploration methods. Recent reworking of pre 1980s surface gravity and vertical component magnetic field measurements showed a coincident but prominent north-south oriented anomaly within the eastern limits of the exploration permit. Because the area is largely free from infrastructural development, aside from the nearby railway track running parallel to the anomaly for some length, it was considered a good site to test the passive seismic method. Collected data was processed using body-wave seismic intereferometry followed by the conventional reflection seismic procedures. The obtained seismic sections show that the anomaly identified by gravity and magnetic surveys is detected at a depth of 450 to 550m and that the causative reflector plunges approximately 40 degrees to the north. Seismic data were dependably processed to a depth of 2.5 km opening the possibility to derive important structural information.