SIG geológico da Vila Cruzeiro do Sul, porção Sul do domínio Bacajá

Abstract

The Cruzeiro do Sul Town, aim of this study, is one of the areas with the greatest lack of geological knowledge in the Bacajá Domain, Transamazonas Province of the Amazon Craton. Recently, an extensive collection of geological information (rock samples, thin sections, geological and thematic maps, structural data, etc.) were generated through field work of graduate students of the Geology course in Unifesspa. This work shows the result of reinterpretation and integration of geological data, produced by geology students, with radar and airborne geophysical images, with the final product generate a geological map in georeferenced base and the making of a database gathering information existing geological and description of the geological setting area of Cruzeiro do Sul Town. The geological map was performed in 1: 70.000 in geological GIS environment, coupled to a bank of vector data in shapefile format files. The geological units are defined in standard polygons and geological structures, drainage and roads are in format lines since the sampling points, farms sites and towns are represented in points format. All information is linked to an organized database with their tables of attributes, describing the information available. Within the GIS Geological, image data is represented by raster files in geotiff format, enabling photo-interpretation of geophysical products magnetometry amplitude of the analytical signal, ternary composition, gamma spectrometry (Thório channel), and topographical, from the digital models of land. The geological map of Cruzeiro do Sul Town shows that this area is characterized by a mosaic of areas of transcurrent shear cruvi-planar interconnected with NW-SE preferred direction and sinistral movement. Enclaves of amphibolite composition and quartz-feldspathic veins are concordant with the foliation of the rocks oriented toward the foliation plane. The dominant units in the area are represented by Cajazeiras Complex and Granulite Novolândia. Based on mineral assemblages and textural aspects, this work suggests individualizing Cajazeiras Complex in three units: 1) orthogneisses granite; 2) paragneiss; 3) charnockites. But the Granulite Novolândia consists of granulite mafic and felsic, and paragneiss (kinzigites). Compared to the Cajazeiras Complex’s rocks, this unit was affected more intensely by shear zones, which show direction NW-SE, which are common the occurrence of foliation SC and porphyroclasts showing sinistral movement of these areas. Amphibolites and migmatites enclaves are bulkier in this unit than in the complex Cajazeiras. This research is a technical-scientific contribution relevant to a region with extreme lack of geological studies, which until today had only geological maps on a regional scale. With the payment of the products available, this study sought to rescue and filter multisource data, consolidating them and thus helping to improve understanding of the geological framework of Bacajá Domain, well as the basis for opening a range of scientific questions, about the origin and evolution of geological units that outcrop in the area of Cruzeiro do Sul Town.