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

Author(s)

da Silva Rosa, Pedro Augusto ; Rubert, Excelso

• Document type: Journal article
• Source: BRAZILIAN JOURNAL OF GEOLOGY; v. 48, n. 2, p. 26-pg., 2018-04-01.

Abstract

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)

• FAPESP's process: 12/06082-6 - The Paraná-Etendeka magmatic province in Brazil: temporal and petrologic relationships between the tholeiitic and alkaline magmatism and geodynamic implications
• Grantee: Excelso Ruberti
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 12/19184-1 - Geology and Petrogenic Evolution of Itatiaia Alkaline Massif, MG-RJ
• Grantee: Pedro Augusto da Silva Rosa
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 15/19974-0 - Determination and interpretation of intensive parameters of Itatiaia Alkaline Massif, Brazil
• Grantee: Pedro Augusto da Silva Rosa
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate