Geophysical structures and tectonic evolution of the southern Guyana shield, Brazil

Aerogeophysical data of an area located on the southern portion of the Guyana shield in Brazil was processed using a fine interpolating mesh, and a corresponding spatial data integration strategy which included the stacking of different high-resolution images, and interpretation following quality control of these. The selected images were correlated to the local known surface geologic units, and to the spatial distribution of the main geochronological provinces of the Amazonian craton. The interpretation of the results also included the available geophysical information for the region, related to Moho depth values, and previously determined SKS shear-wave splitting direction. The observed magnetic regional trends may be strongly influenced by the Proterozoic crustal structure in the area, while radiometric anomalies correlate with the more detailed geologic features. Based on the parallelism among mapped geochronological provinces of the Amazonian craton, and observed geophysical structures on the study area, a geotectonic model is proposed for southern Guyana shield at Proterozoic age.