HYDROTHERMAL REE FLUOROCARBONATE MINERALIZATION AT BARRA DO ITAPIRAPUA, A MULTIPLE STOCKWORK CARBONATITE, SOUTHERN BRAZIL

Author(s)

Ruberti, Excelso ; Enrich, Gaston E. R. ; Gomes, Celso B. ; Comin-Chiaramonti, Piero

• Document type: Journal article
• Source: CANADIAN MINERALOGIST; v. 46, p. 14-pg., 2008-08-01.

Abstract

The Barra do Itapirapua ( BIT) carbonatites in southern Brazil belong to the final stages of the Early Cretaceous alkaline rock - carbonatite magmatism of the Ponta Grossa Arch Province. The BIT complex is a dyke and vein stockwork in which four main carbonatitic phases are recognized, mainly magnesiocarbonatites and ferrocarbonatites. These carbonatites are generally overprinted by pervasive hydrothermal events. The C-O stable isotopic data indicate re-equilibration under hydrothermal conditions at temperatures between 375 and 80 degrees C. Significant amounts of REE fluorocarbonate minerals, relatively Sr- and Th-rich, were deposited. Syntaxy between synchysite-(Ce) and parisite-(Ce) is very common owing to the similarity in structures, with alternating (001) layers of (CeF), (CO3) and (Ca). However, bastnasite-(Ce) occurs as individual crystals, overgrown by the synchysite and parisite polycrystals. Textural and chemical reactions between the REE fluorocarbonates provide insights into the mobility of rare-earth elements during fluid-rock interaction. The BIT complex is considered to be of potential economic interest for production of the rare-earth concentrates. (AU)

• FAPESP's process: 01/10714-3 - The alkaline magmatism evolution in the South American Platform: petrogenetic and geodynamical implications
• Grantee: Celso de Barros Gomes
• Support Opportunities: Research Projects - Thematic Grants