A Multi-Frequency Inductive 5Th Generation Em System For Geophysical Exploration

The multi-frequency inductive electromagnetic systems had their origin in the work by Dias (1968; 1973) and five generations of these equipments appeared in the market since then. The system discussed here belongs to the last generation. It consists of a loop-loop minimum coupling system operating at 54 values of frequency in the interval 1.125 Hz to 10.473 KHz, with transmitterreceiver separation spreading up to 1 km on a terrain of 100 Ωm resistivity background. A scheme is also presented here for processing the field data and constructing<br>2D pseudo-sections for resistivity and polarization parameter. The area test for this experiment is situated on a gnaissic basement covered by intemperized basement rock and quaternary beach sediments on the Farm São João in Rio das Ostras/RJ. This system was capable to discriminate and map a zone of washed sand, probably more indicated for groundwater taking, and a zone where clay minerals are present.