Avaliacao e integracao de dados Landsat-TM, geofisico e geologicos atraves de tecnicas de processamento digital de imagens e sistema de informacoes geograficas / Assessment and integration of TM - Landsat, geophysical and geological data by digitally processed image techniques and geographical information systems

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

In the present study geological, LANDSAT/TM and geophysical data (aerogammaspectrometry - U, Th, K, CT, U/Th, U/K, Th/K; aeromagnetometry - global magnetic field; gravimetry - Bouguer anomaly) were analyzed and integrated to assimilate and adequate methodologies for geological mapping in which all data can be integrated by digitally processed image techniques and Geographical Information Systems. Firstly, a visual interpretation on LANDSAT/TM data was performed aiming at the tectonic positioning of the surveyed area on a regional level. Then, the target area data placed in workstation by format correlation or digitallization were submitted to pre-processing, being geometrically corrected and registered afterwards (coregistered). The geophysical data were converted from vector to raster format and by displayng black and white images, techniques were applied to enhance lithological and structural aspects, such as: contrast stretch, color composite, shaded relief, digital terrain model, slicing and merging with the LANDSAT/TM images by IHS. The images produced were interpreted, assessed and correlated to the geological data avaliable to get as much information as possible from all products. The grouping analysis technique was also used on geophysical data (ISODATA) together with LANDSAT/TM images. The study area is located on the Amazonic Craton, the geology of which is represented by granite-gneissic terrains, magmatic and metamorphic rocks, metasedimentary, sedimentary and volcano-sedimentary sequences. The computer-integrated data techniques have enabled geological information to be presented and treated in many ways, showing that geophysical data in raster format are better than the contour map conventionally used, for providing additional subsidies to geological and geophysical correlation. Thus, lithological units previously documented in the area revaled subnits, as the Santa Helena Granite-Gneisse and the Detritic-Lateritic Cover. The redefinition of possible lithological contacts with the existing units in the application of this methodology should provide not only more geological information about the observations on outcrops and subsequent field stage, but also full data utilization and better profiting from its potentialities by quick and total access to the results of a geological survey program..

ASSUNTO(S)

thematic mappers (landsat) aerial photography fotografia aerea imagens landsat satelites landsat propriedades estruturais (geologia) image processing litologia geology geographic information systems geologia mapeamento geologico sistemas de informacao geografica processamento digital de imagens sgi rio guapore (mg)craton amazonico mapeador tematico (landsat)

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