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EVOLUÇÃO MAGMÁTICA E METAMÓRFICA DE ZIRCÃO DO COMPLEXO BARRO ALTO (GO), COM BASE EM IMAGENS DE ELÉTRONS RETRO-ESPALHADOS E ANÁLISES QUÍMICAS POR MICROSSONDA ELETRÔNICA

1999; Sociedade Brasileira de Geologia; Volume: 29; Issue: 3 Linguagem: Inglês

10.25249/0375-7536.199929371378

ISSN

2177-4382

Autores

Lucy Takehara, Léo Afrâneo Hartmann, M.A.Z. Vasconcellos, MARCOS TADEU DE FREITAS SUITA,

Tópico(s)

Geochemistry and Elemental Analysis

Resumo

Zircon is a mineral much used in U-Pb geochronology because it is considered a closed system and has fairly high quantities of U and Th. In this paper, we study Barro Alto Complex (Goiás, Brazil) zircons by backscattered electrons (BSE) imaging and spatial scanning profiles by waveleng dispersive spectrometer of Hf, Y and U. The BSE images and the profiles show variations in the internai structures and composition of zircon crystals that reflect the magmatic and metamorphic processes in the host rocks. Magmatic features are still observed, but metamorphic processes are registered in different textures on the zircons crystals; some are less affected because they are more resistant. The medium to high grade regional metamorphism of the Brasiliano Cycle is registered in ali studied crystals and it may indicate an open-system geochemistry, that consequently affected the U-Pb isotopic system.

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