Geologia e litogeoquiámica das rochas graniáticas do maciço capão bonito e o contexto geoloágico da sequência vulcano-sedimentar açungui

Abstract

The Capão Bonito Granitic Massif is associated to the granitogenesis evolution of the Mantiqueira Central Province and is situated in the southeast portion of the state São Paulo. It is intrusive in epimetamorphic rocks of Açungui Group, Votuverava Formation, and in rocks of the Três Corregos Granitic Complex. The chief outcrops are found close to the limits of the Paranaá Basin and are partially hidden by sedimentary rocks of the Itarareá Group and by recent sediments of that Basin. Their litotypes are distributed in the form of a prolonged body that is parallel general direction NE-SW associated to the main transcurrent shear zone. They it constituted by red sienogranites, holo to leucocratic with biotite and rare hornblende, inequigranular with medium to thick grains, porfiritic and isotropic to slightly cataclastic in the marginal zones. The Capão Bonito granitic rocks belong to a calc-alkaline suite that defines high-K calc-alkaline to shoshonitic potassic magmatism with dominant metaluminous to peraluminous types. The magmatism is compatible with A- type granite and other late-orogenic to anorogenic intraplaca ambient, with fusion in the lower crust and emplacement of the granite massif associated to the transtensive structures correlated to the shear zones in extensional ambient of the colisional event of the Ribeira Orogenesis.