Integração de imagens Landsat-7/ETM+ e dados aerogeofísicos como auxiliar em programas de mapeamento geológico na região da Folha Vila de Tepequém (NA.20-X-A-III), 1: 100.000 - Estado de Roraima

Abstract

Geophysical data integrated with satellite multiespectral images and radar images are being used with success in geological mapping. The Geological Survey of Brazil (CPRM) made in 2001 the Parima-Urariquera Aerogeophysical Project in the northwest area of the Roraima State. Airbone Magnetic and Gamaespectrometric data were collected with lines of flight of 500m of spacing and a medium height of 100m. his work presents the results obtained at the Vila de Tepequém (NA20-X-A-III) map, resultants of the integration of the geophysical data with multiespectral images of the satellite LANDSAT 7 ETM+. In the integration process were used LANDSAT 7 / ETM+ images, bands 3, 4, 5 and 7, corresponding the scene 57 of the orbit 233, acquired in March 15, 2000 and the data of the channels of Uranium (U), Thorium (Th), Potassium (K) and Total Count (CT) and magnetometrics (Residual Field). The original geophysical data were transformed in form of regular network with 125 m spacing and, later, turned for the format of digital images into gray tones through the software SPRING/INPE. The data integration was accomplished through the IHS transformation techniques, being obtained the components I, H and S initially, from the bands 3, 4 and 5 of the image LANDSAT. After several combinations of substitution of the components I, H and S they were made, for the generated geophysical images of the several channels, for synthetic images of DN constant same to 60 and/or for the first principal component of the images LANDSAT, generating several images integrated that were submitted to the analysis and fotointerpretation. The integrated images allowed the united visualization of the geophysical, morphologic and structural characteristics of the litologic and tectonic units, as well as your distribution and space configuration. The results present an excellent discrimination for the geological features of the studied area, where it was possible to identify 14 different units. Six of those units were already correlated to the litologies known of the area and eight were recognized in this work, besides, it was possible the definition of the parameters of the geophysical characteristics of the units studied at the Vila de Tepequém map, what makes possible your correlation with other units in adjacent areas. The obtained results prove that the resulting products of the methodology of digital integration of geophysical data of high resolution and images of satellite, through the transformation IHS, reveal more detailed and more necessary information than if the data were used separately, being minimized the difficulties of obtaining of geological data in areas of difficult access, optimizing time and cost, turning the more effective field campaigns.