Geologia e geoquímica do Granito Itaoca

• Autor(a) principal: Zenero, Jonas Menezes [UNESP]
• Data de Publicação: 2017
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/203219; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2018-12-11/000909657.pdf
• topic: Granito; Geologia; Geoquímica; São Paulo (Estado); Parana

The Itaoca Granite is an intrusive circular batholite of 200 km2, located between the state of São Paulo and Paraná. It has a calcium alcaline composition, and its approximate age of 623 million years, has its genesis associated with the neoproterozoic evolution of the Mantiqueira Central Province. Its nesting rocks make up the Açungui Supergroup and present in the environments of the batholith with mineralogy typical of contact metamorphism. Thus facilitating the identification of the granitoid with the use of remote sensing images. Using textural, structural, staining and compositional aspects of the rock the massive was divided into three units and subdivided into 6 facies. They are the units Itaoca, Ribeira and an association of undifferentiated facies. Petrographically their rocks constitute basically hornblende-biotite-quartz monzonites to holo- to leucocratic monzogranites. They have porphyritic, unequigranular texture, medium to coarse granulation, isotropic to suboriented. The unit Itaoca constituted of rocks less evolved (quartz monzonites), possibly because it is a primary magmatic pulse in front of the unit ribeira. Geochemically, the granitoid is a peraluminous granite, type I cordilherian, syn to late collisional that intruded in a magmatic arc by the fusion of the inferior crust. Occurring during the Brazilian collision event, more specifically in the Apiaí orogen, between the initial, thrust falt, and final stages, of shearing. The deformations generated by the shear zones, referring to the lateral escape efforts, produced the milonitic to metagranitic rocks. They occur in the margins of the granite body, closer to the shear zones, and due to the difficulty of determining the facies belonging, make up the unit of associations of undifferentiated facies