SIGNIFICANCE OF GARNET-BEARING METAMORPHIC ROCKS IN THE ARCHEAN SUPRACRUSTAL SERIES OF THE CARAJÁS MINING PROVINCE, NORTHERN BRAZIL

CARLOS EDUARDO DE MESQUITA BARROS, PIERRE BARBEY

Resumo


The Archean evolution of the Carajás Mining Province was marked by the emplacement of syntectonic alkaline granites (cf. Estrela and Planalto granites) at 2,75 Ga. The Estrela Granite Complex produced changes in tectono-thermal conditions and rheology of its volcano-sedimentary host rocks (Salobo, Pojuca, Grão-Para and Rio Novo groups). Metamorphic recrystallization in the contact aureole around the Estrela Granite Complex reached hornblende and pyroxene hornfels facies. The aureole is characterized by the local presence of schists containing abundant snowball garnet porphyroblasts indicating a top to south movement related to emplacement of the Estrela Granite Complex. It is suggested that occurrences of garnet-bearing schists, near Salobo and Pojuca areas, may represent tectono-metamorphic aureole around other Late-Archean syntectonic granite bodies.

 


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