Nepheline syenites to syenites and granitic rocks of the Itatiaia Alkaline Massif, Southeastern Brazil: new geological insights into a migratory ring Complex

Autor(es)

da Silva Rosa, Pedro Augusto ; Rubert, Excelso

• Tipo de documento: Artigo Científico
• Fonte: BRAZILIAN JOURNAL OF GEOLOGY; v. 48, n. 2, p. 26-pg., 2018-04-01.

Resumo

The Itatiaia Alkaline Massif comprises some of the largest meso-cenozoic alkaline igneous occurrences in Brazil, covering over 215 km(2) between the states of Minas Gerais and Rio de Janeiro. It appears as an elongated, 30-km long and 4.5-11.5-km wide SE-NW-trending body emplaced along accommodation zones of the Continental Rift of Southern Brazil, intruding metapelites,orthogneiss and granites of the Brasilia and Ribeira fold belts. New data and geological mapping suggest that the massif evolved from a migratory magmatic center manifested as ring structures and successive moon-shaped intrusions from SE to NW in three sectors of distinct lithological and geomorphological characteristics: Southeastern, Central and Northwestern. The lithological variants in the three sectors present themselves as discrete intrusive bodies, comprising feldspathoid-bearing and quartz-bearing syenites, porphyritic to breccioid trachytes, granite, monzonite, gabbro and trachybasalt, which can be grouped into 21 units. These rocks occur in five petrographical sets: plagioclase-free nepheline syenites, plagioclase-bearing nepheline syenite and pulaskites, nordmarkite-granite series, anti-rapakivi associations and basic rocks. Sin-to tardi-plutonic dykes of nephelinites, phonolites, trachytes and rhyolites are also present. (AU)

• Processo FAPESP: 12/06082-6 - A província magmática Paraná-Etendeka no Brasil: relações temporais e petrológicas entre o magmatismo toleítico e alcalino e suas implicações geodinâmicas
• Beneficiário: Excelso Ruberti
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 12/19184-1 - Geologia e Evolução Petrogenética do Maciço Alcalino de Itatiaia, MG-RJ
• Beneficiário: Pedro Augusto da Silva Rosa
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 15/19974-0 - Determinação e interpretação dos parâmetros intensivos do Maciço Alcalino de Itatiaia, Brasil
• Beneficiário: Pedro Augusto da Silva Rosa
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado