Geobotânica por sensoriamento remoto e aerogamaespectrometria aplicados ao mapeamento geológico da Amazônia: um estudo comparativo no vale do Guaporé (MT)

Abstract

Remote sensing geobotany and airborne gamma-ray data applied to geological mapping of the Amazon: a comparative study in the Guapore Valley (Mato Grosso State, Brazil) This paper comprises a comparison between the vegetation response in ASTER multispectral optical imagery and possibly equivalent bedrock/regolith/soil response in airborne gamma-ray spectrometry grids, employing two tropical rainforest areas in the Brazilian Amazon as controls. The applied technique comprised band ratios using a fixed near infrared band (numerator) divided by individual visible and shortwave infrared bands (denominator). These band ratios were subsequently submitted to principal component analysis, and the high frequency information smoothed by low pass filtering. The color compositions selected for interpretation were sharpened by the first principal component of the originalASTER bands through an IHS transform in order to add albedo/ texture information - lost by band rationing - back to the imagery. The products show a plausible coherence with airborne gamma-ray data and field observations, proving that the proposed processing strategy applied to low cost multispectral data can provide useful geologic information in inaccessible vegetaded areas of the Amazon.