THE KAMAFUGITE-CARBONATITE ASSOCIATION IN THE ALTO PARANAÍBA IGNEOUS PROVINCE (APIP) SOUTHEASTERN BRAZIL

JOSÉ AFFONSO BROD, SALLY A. GIBSON, ROBERT N. THOMPSON, TEREZA CRISTINA JUNQUEIRA-BROD, HILDOR JOSÉ SEER, LÚCIA CASTANHEIRA DE MORAES, GERALDO RESENDE BOAVENTURA

Resumo


The Late-Cretaceous Alto Paranaíba Igneous Province (APIP) comprises a variety of ultrapotassic rock-types, including kimberlites, lamproites and large volumes of kamafugites, in addition to a number of carbonatite-bearing plutonic alkaline complexes. Phlogopite-picrites are ultramafic fine-grained rocks typically composed of olivine phenocrysts set in a groundmass of phlogopite, carbonate, perovskite, apatite and chromite. They occur as dyke swarms in the carbonatite complexes, but are also scattered throughout the Province. The phlogopite-picrites represent the peralkaline, ultrapotassic, carbonate-rich, silicate magmas parental to the carbonatite-bearing complexes, and have strong chemical affinity with kamafugites. Together with petrographic similarities observed between silicate rocks from the carbonatite complexes and xenoliths occurring in APIP kamafugites, this provides a strong link between kamafugitic and carbonatitic magmatism in the Province.


Palavras-chave


Kamafugite; Carbonatite; Phlogopite-picrite; Ultrapotassic; APIP.

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