GAMMA RAY SPECTROMETRY AND LANDSAT TM SATELLITE IMAGES APPLIED TO THE STUDY OF THE SEDIMENTARY PHOSPHATES OF IRECÊ BAHIA (BRAZIL)

Abstract

This work aims to study phosphate exploration areas through the application of gamma-ray spectrometry and remote sensing, using satellite images of Landsat Thematic Mapper ( TM ) sensor. The selected zone for this study is located in the Irece region (Bahia State, Brazil). Geologically it represents an environment with phosphate deposits, associated to the Precambrian limestone of the Una Group. The presence of this mineralization was discovered and prospected by the “Companhia de Pesquisa de Recursos Minerais” (CPRM; Company of Research of Mineral Resources) and the “Companhia Baiana de Pesquisa Mineral” (CBPM; Bahia State Company of Mineral Research). This is a relevant issue due to the importance of this mineral resource to Brazil economy. The satellite images and gamma ray maps analyzed in this work: evidence that 232 Th anomalies have the best relationship with the data obtained by the CBPM through geological mapping; allowed to identify two new other potential mineralization areas in Irece region; are useful for mapping phosphates concentrations and to identify new potential areas of phosphate mineralization.