Geologia do platô N6 - província mineral de Carajás (SP)

• Autor(a) principal: Motta, João Gabriel [UNESP]
• Data de Publicação: 2011
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/120109
• topic: Metalogenia; Minerios de ferro; Mapeamento geologico; Geologia economica - Brasil; Carajas, Serra dos (PA); Metallogeny; Carajás Mountains (Brazil); Geological mapping; Geology, Economic; Iron ores

The N6 Plateau presents an iron-ore occurence in Carajás Mineral Province, standing near to actually operating deposits. Geological mapping in 1:10,000 scale and integration of geochemical, geophysical, petrography and drilling turns possible interpretation of his geological evolution. The mapped area has lithotypes from Archean Grão Pará Group, comprising very lowgrade metamorphic basic rocks and iron formation and an Proterozoic sedimentary association of conglomeratic sandstones called as Caninana Unity. The structural geology in given by a regional scale homoclinal, where the Grão Pará Group strata dips towards SW, as a part of the Northern Limb of the Carajás Fold. Subsequent deformation associated to the installation of the Carajás Shear Zone presents as E-W fold axis. Geochemical evidence permits to consider de Parauapebas Formation as the rocks which has been hydrothermally-altered to outsourcing fluids responsible to deposition of iron formations in the oceanic system, including different signatures which can be interpreted as possible sub-embayments in the Carajás Basin. The iron ore in the area occurs in subsurface as very fine friable hematite generated by supergenous enrichment of the iron formation. The conceived geologic model differs from the current academic proposal on the fact that hydrothermal alteration has been involved on the jaspelite enrichment. Metamorphism on the Parauapebas Formation presents paragenesis considered as ocean-floor metamorphism which precedes de deformation insofar as the rocks show no tectonic fabric referring to shallow crust evolution. Geophysical methods such as magnetometry and gravimetry presents excellent results for structural interpretation in uneven exposed terrain