Recomendação Para Sondagem no Núcleo Pré-Cambriano do Rio Grande do Sul

Copper showings are frequently found in the Precambrian Nucleus of Rio Grande do Sul, but only the Camaquã deposit was economically exploitable. An exploration strategy based on geophysical methods was adopted in area to prospect for copper deposits of the massive sulphide type. In 1977, 7200 line km of helicopter electromagnetic (HEM) and magnetic surveys were executed in areas mapped as Vacacaí and Bom Jardim Formations. HEM responded to two types of conductors a) extensive surficial layers, which show lithologically dependent resistivity; b) sheet like bodies. Ground geophysical measurements were executed over selected anomalies. TURAM and magnetic measurements were executed on a grid of 100 x 25 m. In some target areas also induced polarization and gravity were employed. Also detailed geochemical sampling and geological mapping were performed in target areas of 500 x 500 m. On the basis of geophysical, geochemical and geological surveys drill holes were suggested to explain sources of anomalies. The same meaning that, only one disseminated sulphide body were detected during the 1977; another magnetic anomaly was founded on the ground, out of the HEM target, and was re-interpreted 34 years after (2011).