Caracterização química, mineralógica e espectral em pegmatitos litiníferos de Araçuaí – MG e aplicação em prospecção mineral por sensoriamento remoto

Abstract

This study investigated the prospecting and analysis of pegmatites in two areas of southeastern Brazil, aiming to characterize samples geologically and to assess the viability of using spectral and chemical methods as vectors for lithium mineralization. Field activities included the collection of rock and soil samples from pegmatites in the Araçuaí and Engenheiro Schnoor regions, which were prepared and homogenized to ensure mineralogical representativeness. In the laboratory phase, petrographic analyses revealed features of minerals such as potential pyroxenes, micas, and feldspars, while X-ray fluorescence analysis with the S1TITAN highlighted elevated values of elements like hafnium and rhodium associated with pegmatites. Spectral analysis indicated characteristic absorption features related to minerals with Al-OH bonds, such as muscovite, kaolinite, and halloysite, enabling mineral identification through minimum and Euclidean distance classification methods. Less prominent features of ferrous minerals, such as hematite and goethite, were also observed. For ASTER data preprocessing and atmospheric correction, QGIS was used, and scene processing was performed on the Google Colab platform. During processing, the data were resampled to ASTER spectral resolution, clustered, and analyzed per class, with one representative class from the study area being used to map similar spectra in the region. The methodology proved efficient for identifying indicator minerals and suggesting mineralogical associations useful for prospecting studies using spectral data, although limitations were noted due to errors and constraints in the field spectral acquisition process and its application to orbital sensors. Integration with geophysical and geochemical methods is proposed for more precise discrimination of anomalous areas.