CARACTERIZAÇÃO MINERALÓGICA E COMPOSIÇÃO QUÍMICA DAS INCLUSÕES FLUÍDAS DE BERILO DO PEGMATITO IPÊ, MUNICÍPIO DE GOVERNADOR VALADARES. MINAS GERAIS.

Abstract

The Ipê pegmatite is situated to the northwest of Minas Gerais State, Brazil, and belongs to the MarilacPegmatitic Field of the Província Pegmatítica Oriental do Brasil. The essential minerals found are: Kfeldspar,quartz, muscovite and biotite. The accessory minerals are: kaolin, albite, apatite, beryl, niobiumtantalite,garnet and tourmaline. The beryl crystals always contain abundant primary and pseudosecundaryfluid inclusions composed essentially by aqueous solutions of low salinity. Eutetic temperature data andmicro-Raman and infrared Spectroscopy analyses of the inclusions of the samples from the graphic andintermediate zones, and from the substitution body suggest that the fluids have evolved from systemswhich were originally enriched in Na+, K+, and possibly Fe2+ and Fe3+ (± CO2 ± CH4 ± N2) to Ca-richersolutions, with more abundant CO2. The fluid homogenization temperatures corroborate this evolutionhypothesis and additionally suggest that the inclusions from the graphic and intermediate zones werereequilibrated by later solutions.