Abstract:
The Amazon Basin has an area of approximately 500.000 km2 covering part of the states of Pará and Amazonas. The region studied is located in the southwest portion of the basin (near of Itaituba - PA city) and contains sedimentary rocks of the Fanerozoic cover and the basement in the Amazon Central Province. Structural analysis consisted of multiscale analysis and integration of images analysis (recognition of morphotectonics features in images SRTM, using data from aeromagnetometria) and using data from the feld to determine structural framework and defne the stages of post-paleozoic strain that hit the area. From the data of failures and systems of joints, shear zones, slickenside and steps found in outcrops, were developed the structural and kinematic analysis. The application of the method to determin the paleostress could to set the position of stress. The results indicate at least 3 stages of strain active at the end of the Paleozoic. The frst phase (F1) has dextral kinematic and structure frontal position N60-70E, for maximum stress (σ1), allows the compressive stresses, although in a transcurrent context, correlated to the orogeny responsible for the formation of Pangea at the end of the Permian. The second phase (F2) is characterized by the presence of normal faults of NE direction coincident with the positioned dikes in the region, may be related to magmatism Penatecaua. The third phase (F3) would be related to a system composed of the combined structures N50-70W (sinistral) and N60-70E (dextral) with direction of σ1 E-W. Only this phase appears to have affected the cenozoic rocks, and probably is related to the spread of strains of Andean subduction.
Keywords:
Amazon Basin; structural analysis; paleostress