Geophysical investigations and marble quarry exploitation in south Portugal

The marble industry is a very important economical activity in the Evora and Beja districts (South Portugal) where marble exploitation has been going on for more than a century. Some specific exploitation problems, such as overburden thickness and bedrock karstic topography, geological boundaries of marble formations and fracture detection, as well as their behaviour, can benefit from the use of appropriate surface geophysical techniques. In fact there are examples of the use of electrical measurements to delineate bedrock topography and conductive channels (Ogilvy et al, 1991, and Sporry et al, 1997). On the other hand, small fracture detection poses different difficulties and some experiments involving the use of Ground Probing Radar techniques have been carried out (Gourry et al, 1996 and Grandjean et al, 1996). Here in we discuss the use of EM conductivity surveys and of GPR techniques as tools in marbie exploration. Futhermore, processing and use of GPR data is analysed so that GPR sections are clearer for interpretation and fracture diagnosis.