Brittes A.F.N.,Federal University of Mato Grosso |
Brittes A.F.N.,Research Group in Crustal Evolution and Tectonics Guapore |
Brittes A.F.N.,Federal University of Pará |
De Sousa M.Z.A.,Federal University of Mato Grosso |
And 10 more authors.
Brazilian Journal of Geology | Year: 2013
This work presents the results of the geological mapping and the petrological characterization of the Serra da Bocaina Formation belonging to the Amoguijá Magmatic Arc of the Rio Apa Terrain. In the Bocaina hills, the Serra da Bocaina Formation consists of intermediately to predominately acidic volcanic rocks, classified as andesites and rhyolites and subdivided into five petrographic facies, which include four volcanoclastics and one effusive. In the studied rocks, tectonic structures are generated in two compressive ductile to ductile-brittle deformational phases. The first phase, which is more intense, presents along the entire studied area and is responsible for the Santa Rosa Shear Belt, whereas the second phase is more localized. The geochemical study indicates a calc-alkaline magmatism of medium to high K, peraluminous, and generated in a volcanic arc environment. These volcanic rocks formed in an explosive environment related to the Amoguijá Magmatic Arc, as indicated by their Pb-Pb zircon age of 1877.3 ∓ 3.9 Ma.