HYPERSPECTRAL REMOTE SENSING FOR MINERAL MAPPING: A CASE-STUDY AT ALTO PARAÍSO DE GOÍAS, CENTRAL BRAZIL

Abstract

After many decades of successful advances in applying multispectral remote sensing to the study of the Earth's characteristics and processes, a new data acquisition technology is emerging: hyperspectral remote sensing. This technology comprises the remote measurement of specific chemical and physical properties of surface materials through imaging spectroscopy. In this paper we examine the capability of hyperspectral remote sensing data acquired by the AVIRIS airborne instrument, over an area near Alto Paraíso de Goías. This area was chosen as a function of data availability, and not due to its geological characteristics. It comprises Proterozoic metasediments with little mineralogical variations and, although it does not represent an ideal site for the use of hyperspectral data, some interesting results were found in terms of mineral identification in portions of the image where enough ground exposure existed. Mineral assemblages, comprising mixtures of primary and secondary minerals, the latter related to weathering processes, were identified in the imagery, based solely on spectral signatures of pixels. These mixtures comprised mainly hematite, goethite, halloysite, kaolinite and Na-montmorillonite. Results were confirmed by laboratory reflectance measurements and scanning electron microscope (SEM) analysis of soil samples, demonstrating the usefulness of AVIRIS data and the efficiency of the methods employed for remote mineral mapping. However, vegetation showed to represent a constraint for mineral mapping, since it is likely to conceal spectral information due to rocks and minerals.