Modelagem prospectiva mineral com base em Lógica Fuzzy: avaliação do Distrito Ferrífero de Quiterianópolis/CE

Abstract

Recently the state of Ceará, Brazil, has been an important iron ore producer and exporter, by Bandarra mine in Quiterianópolis city. In this city there are five known iron occurrences named Calixto, Bandarra, São Francisco, Olho D’água and Pintada. The Bandarra iron ore deposit produced and exported from Brazil to China about 1.2 million tonnes of iron ore with 60% content. These iron ore are located in Northern Borborema Province, Ceará Central Domain, between Transbrasilian belt and Taua Shear Zone, Acarau Sudomain. There are redominantly gneisses of Canindé do Ceará. Complex, metasedimentary rocks of the Novo Oriente Group, granitoids of Tamboril-Santa Quitéria Complex and cenozoic deposits. This research proposes the application of the Fuzzy Logic Method (knowledge-driven), involving airborne geophysics and remote sensing imagens from Landsat ETM+(Enhanced Thematic Mapper Plus), to make an iron prospectivity model of the Quiterianópolis region. The Fuzzy Logic is the simplification of raster data through application of fuzzy membership functions and integration by fuzzy operators. The iron prospectivity model was created with the Total Horizontal Gradient (THDR), Analytic Signal Amplitude (ASA), %K, eTh, eU, Total-Count Gamma Radiation, PC1, PC3, PC5, PC6 and ETM 3/1, 4/1 e 5/7 Ratios. The iron prospectivity image show three prospectivity classes: low, medium and high. The iron ore deposits are located on high propectivity classes, serving as a reference for prospectivity model validation. We concluded that Fuzzy Logic technique is a powerful tool in the early stages of mineral exploration.