Análise estrutural das rochas metassedimentares da formação buritirama, da mina de buritirama, Marabá – PARÁ

Abstract

This work presents the structural analysis of metasedimentary rocks of the Buritirama Formation that occur in the homonymous mine. The mine is situated in the boundary between the north of the Carajás Province and the southeast of the Transamazonas Province, specifically in Vila União, appoximadetly, 130 kilometers from the city of Marabá, southeastern Pará. The Buritirama Formation, of supposedly archean age, comprises mainly mica quatzites, calc-silicates rocks, mica schists and Mg-rich schists. In addition, these rocks are associated with lenses and layers of Mn ore, products of oxidation and supergene enrichment, which can reach 60 meters of depth. To carry out this research, remote sensing data, as well as structural and microstructural data were collected in order to establish the structural correlation among regional, local and microscopic scales. The analysis of tectonic structures allowed to recognize three deformational events: D1, D2 and D3. The first event (D1) has been interpreted as a ENE-WNW shortening direction that originated the NNW-SSE foliation (S1) direction, in the compressional tectonic regime associated with the Transamazonic Cycle (2.5-2.1 Ga). The (D2) deformation event is characterized by the formation of the foliation (S2) and the folds (Fn), both related to a NW-SE compressional direction, influenced by the orosirian Sereno Tectono-Termal event, dominated by a ductile shear zone. The last deformational event (D3) is associated to the presence of faults and fractures that occur cutting those horizons previously mentioned and it is related to the neoproterozoic Araguaia Belt.