Neves Corvo, Portugal
... results show the UTEM system to be a useful tool for both detection and evaluation of large conductive deposits at depth in the Pyrite Belt environment. It is estimated that a deposit such as Neves Corvo would be detectable to much greater depths in this environment or, alternatively, at a similar depth in a more conductive environment.
The two survey lines were situated directly over the Neves and Lombador deposits and roughly 500m from the mine installations. The UTEM3 survey was considered very successful because it detected the massive sulphides as a very clear, broad response with a 15-25ms time constant in spite of two major power lines that crossed the lines in the area of the target. The response measured with the southwest loop would have been considered exceptional in any routine coverage, the response measured with the northeast loop would have called for followup work using additional loops located to the southwest.
Not only were there no difficulties with the depth of the target or the presence of shallower conductors, the UTEM3 data and MultiLoop modelling provided generally accurate information about the characteristics of the conductor and the conductive layers above it.