Caracterização de ocorrência de minério de ferro bandado por meio de integração geofísica no complexo metamórfico Arroio Marmeleiro – município de Bagé-RS

Abstract

Geophysical methods are widely used in the research of all kinds of mineral deposits, including iron ore. This paper presents the results of the application and integration of methods of resistivity, magnetometry and magnetic susceptibility. Data integration aims to recognize the distribution and geometry of the orebody belonging to Metamorphic Complex Arroio Marmeleiro (CMAM), located in the municipality of Bagé RS. The CMAM occurs as an elongated body parallel to the lineament of Ibaré and consists of metamorphic lithologic sequences of greenschist facies to amphibolite among which included metapelites, carbonaceous metapelites and talc schists associated with carbonate rocks, amphibolitic and metavolcaniclastic. Understanding the lithology of the region in CMAM was performed starting with geological approaches to petrographic and structural, and geophysical seeking the delimitation of the mineralized body. Geophysical analyzes were employed in the subsurface, the geoelectrical method and the magnetometric resistivity method, and also portions outcropping soil and the method of magnetic susceptibility. The magnetometric and magnetic susceptibility maps are perfectly correlated, proving that the region studied is rather anomalous features that are interpreted as mineral deposit ore banded iron. Low magnetic susceptibility values (0:08 to 5 x 10-3) were interpreted as alteration products and developed soils and high values (> 5 x 10 -3) as representative of soil or rocks with fragments of interest. The electrical resistivity profile generated by resistivity technique was employed using the Wenner-Schlumberger array, seeking the interpretation of the average thickness, which was approximately 50 meters. The study was conducted in detail and scale, from the information acquired, proved the existence of the lithology of interest along substantially the whole area analyzed by integrating the geophysical data that showed characteristic faults. As end products, information was generated that reveal the structural control and petrography iron deposit under study, as well as its distribution and geometry along the study area.