Radar, geologic, airborne gamma ray and landsat tm digital data integration for geological mapping of the estrela granite complex (PA). / Integração digital de imagens de radar e landsat-TM dados geológicos e aerogamaespectrométricos no auxílio ao mapeamento geológico da região do complexo granítico estrela - Pará (PA).

Edson Ricardo Soares Pereira da Cunha

This work is focused on the geotectonic context of the Carajás Mineral Province, Amazon Craton, which represents the most important Brazilian Mineral Province and hosts iron, cooper, gold, manganese and nickel deposits. At the end of Archean age, during the tecno-metamorphic evolution, moderated alkaline granitoids were generated, such as, Estrela Granite Complex (EGC). This work has used digital integration products with the purpose of study the granite suite, its host rock, and the surrounded area. The digital integrated data were gamma-ray and geological data with satellite images (SAR-SAREX e TM-Landsat). The geophysics data, originally in 32 bits and grid format, were interpolated and converted to 8 bits images. The geological data (facies map) was digitalized and converted to a raster format. The remote sensing images were geometrically corrected to guarantee an accuracy on the geological mapping. On the data processing phase, SAR images were digital integrated with gamma-ray data, TM-Landsat image and the raster facies map. The IHS transformation was used as the technique to integrate the multi-source data. On the photogeological interpretation, SAR data were extremely important to permit the extraction of the main tectonic lineaments which occur on the following directions: +/- N45W, +/- N70W, +/- NS, +/- N20E, +/- N45E e +/- N75E. This procedure was done both in analogic and automatic form, being the automatic process more useful to complement information in the extracting process. Among the digital products generated, SAR/GAMA products (uranium, thorium and total count) were the ones that give the most important contribution. The interpretation of the SAR/GAMA s products added to the field campaign have allowed to map the limits of units that occur in the region and four facies of the Estrela Granite Complex were detected. The origin of the granite suite might be related to a magmatic differentiation or to distinct intrusion pulses. The use of the digital integrated products has showed to be extremely useful for basic geological mapping, especially to aid field campaign and the selection of key areas for detailed verification. As a final result, this research has allowed to propose obtained a geologic map of the Estrela Granite Complex area.

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