Late-stage magmatic to deuteric/metasomatic accessory minerals from the Cerro Boggiani agpaitic complex (Alto Paraguay Alkaline Province)

Author(s)

Comin-Chiaramonti, Piero ; Renzulli, Alberto ; Ridolfi, Filippo ; Enrich, Gaston E. R. ; Gomes, Celso B. ; De Min, Angelo ; Azzone, Rogerio G. ; Ruberti, Excelso

• Document type: Journal article
• Source: Journal of South American Earth Sciences; v. 71, p. 14-pg., 2016-11-01.

Abstract

This work describes rare accessory minerals in volcanic and subvolcanic silica-undersaturated peralkaline and agpaitic rocks from the Permo-Triassic Cerro Boggiani complex (Eastern Paraguay) in the Alto Paraguay Alkaline Province. These accessory phases consist of various minerals including Th-U oxides/silicates, Nb-oxide, REE-Sr-Ba bearing carbonates-fluorcarbonates-phosphates-silicates and Zr-Na rich silicates. They form a late-stage magmatic to deuteric/metasomatic assemblage in agpaitic nepheline syenites and phonolite dykes/lava flows made of sodalite, analcime, albite, fluorite, calcite, ilmenite-pyrophanite, titanite and zircon. It is inferred that carbonatitic fluids rich in F, Na and REE percolated into the subvolcanic system and metasomatically interacted with the Cerro Boggiani peralkaline and agpaitic silicate melts at the thermal boundary layers of the magma chamber, during and shortly after their late-stage magmatic crystallization and hydrothermal deuteric alteration. (C) 2016 Elsevier Ltd. All rights reserved. (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: 13/18073-4 - Alkaline magmatism of the Brazilian Platform: petrology and geochemistry
• Grantee: Celso de Barros Gomes
• Support Opportunities: Regular Research Grants