Levantamento de ocorrências de rochas metamórficas e suas relações estruturais nos municípios de Brejo Grande do Araguaia e Palestina do Pará

Abstract

In the region between the municipalities of Brejo Grande do Araguaia and Palestina do Pará, a lithological variety was identified, among metamorphic, igneous and sedimentary rocks, belonging to the tectonic features of the Araguaia-Tocantins Belt and the Parnaiba Basin respectively. The geological survey of the area involved studies and petrographic and structural analyzes that allowed a new characterization of the geology of the area, through the identification of the geological units belonging to the Morro do Campo Formation and Formation Group Xambioá Formation, sedimentary rocks belonging to the Parnaiba Basin, Dykes of mafic composition, and lateritic coverings. As well as analyzes of the metamorphic rocks through the identification of the metamorphic and deformational processes to which the rocks were submitted. The rocks of the Parnaiba Basin found in the area are represented by interpolations from decimetric to metric levels of siltstones, sandstones, argillites and silexites. Mafic rocks formed by blocks of diabase and rocks covered by a lateritic crust capping saws and flattened hills forming erosion resistant tops forming the Lateritic Coverings. The Morro do Campo Formation consists of ferruginous Quartzites of solid texture with intercalations of quartz and hematite crystals, with foliation with preferential direction for NW-SE and NNE-SSW marked by the intercalations of quartz crystals and ferruginous crystals. The Xambioá Formation is represented lithologically by Muscovite Slate, Muscovite phyllite, Epidotite Phyllitic, Muscovite Schist, Chorite-Muscovite Schist, Epidote-Oligoclase-Muscovite Schist and Epidote-Biotite-Muscovite Schist, with a preferred trend for NW-SE, NNW-SSE, NE-SW, characterized by different deformation patterns generated as a result of the stresses occurring at different moments of the deformation event of the Araguaia-Tocantins Belt. In that the main metamorphic event was implemented the regional metamorphism varying from Prehnite-pumpellyite facies and Green schist facies, being identified three metamorphic zones in the area, Muscovite Zone, Chlorite Zone and Biotite Zone, characterized by different mineralogical and textural associations.