Paulo Veneziani

Integrating airborne SAR, Landsat TM and airborne geophysics data for improving geological mapping in the Amazon region: the Cigano Granite, Carajas Province, Brazil

This study examines the value of integrating airborne C‐band Synthetic Aperture Radar (SAR), Landsat Thematic Mapper (TM) and airborne gamma spectroradiometric data with field, petrographic and geochemical data for geological mapping of the Cigano batholith, an important representative of the Paleoproterozoic granitic magmatism in the Carajás Mineral Province (CMP), Amazon region. Distinct schemes for the integration of radar/optical and radar/optical/gamma data were evaluated and the geological information derived from the integrated products was verified in the field. The investigation allowed the re‐evaluation of previous geological information and the definition of distinct domains within the Cigano pluton and country rocks. The importance of brittle structures related to the tectonic evolution of the area and the location of intensely altered zones in the pluton was emphasized, favouring new insights into current geological and exploratory models of the area. The application of a similar approach as operational routine in exploration programmes in the Amazon region is justified considering the limited geological information, the availability of aerogeophysical data and airborne/spaceborne remote sensing data (radar, optical) and the high costs of field mapping in this kind of terrain.

Caracterização geológica e estrutural através da interpretação do produto integrado TM-Landsat 5 e dados aerogamaespectrométricos, região de Alta Floresta - MT

This paper deals about the geological, tectonic and structural characterization in the Alta Floresta Gold Province region, MT, through the digital integration of TM-Landsat and gamma ray spectrometry data (total count). The total count - TM integrated product has the essential features for geological interpretation. This product shows structural features from the drainage pattern and relief elements (TM image) and shows the radiometric values (RGB) that contribute to the differentiate lithostructural units. The geological map was composed based on the total count radiometric values interpretation (considering the topography and anthropogenic interference on the radiometric response), in the relief and drainage patterns features (TM image) and field data. Considering the intense anthropogenic activities in the area and almost flat terrain (that prejudice the geological interpretation of remote sensing image), the integrated products generation (TM-gamma) was decisive to the obtention of indispensable data to the mapping. The final product was the geological map of area, in the 1:250.000 scale, with delimited 10 lithostructural units, directly related to radiometric units and structural features. In addition, remarkable N60-70W trend strike-slip systems (ductile and ductile brittle shear zones) were detected and characterized through visual interpretation of the integrated products and field verification.