STATISTICAL CHARACTERIZATION OF GREENSTONE SEQUENCES USING MAGNETIC AND "GAMMA-RAY SPECTROMETRIC DATA, GUARINOS-PILAR DE GOIÁS AREA, BRAZIL

Abstract

All over the world, many mineral deposits are related to greenstone sequences. In Brazil, these greenstone sequences show gold, silver, copper, nickel, talc, iron and manganese mineralizations. Therefore, identification of greenstone sequences is an important step in mineral exploration programs. More man 50% of Brazilian territory is covered with airborne magnetic and gamma-ray spectrometric data. Interpretation of these data can improve me geological knowledgement. Application of a statistical classification method on magnetic and gamma-ray spectroinetric data from the Guarinos-Pilar de Goiás area allowed identification of the main geological units. Integrated interpretation of magnetic and spectrometnc data supplied better results than those obtained using only the gamma-ray information. The best results were obtained by using the changes in magnetic pattern rather than the total field intensity. With G-mode cluster analysis it was possible to discriminate the existing greenstone sequence and to separate its metasedimentary unit from metavolcanic units. Results indicate areas with no correspondence between statistical groups and mapped geology. These areas should be investigated by field work. Greenstone units identified by the statistical procedure are known to be mineralized. Therefore, the method could be used in guiding mineral exploration programs in the region.