GEOCHEMICAL SIGNATURE OF THE BRASILIANOAGE PLUTONISM IN THE SERIDÓ BELT, NORTHEASTERN BORBOREMA PROVINCE (NE BRAZIL)

MARCOS ANTONIO LEITE DO NASCIMENTO, ALEX FRANCISCO ANTUNES, ANTONIO CARLOS GALINDO, EMANUEL FERRAZ JARDIM DE SÁ, ZORANO SÉRGIO DE SOUZA

Resumo


The Seridó Belt (Borborema Province, NE Brazil) displays a strong imprint of the late Neoproterozoic Brasiliano orogenic cycle. The most important megascopic structures in the Seridó Belt are strike-slip shear zones, coeval with the emplacement of several granitoid bodies. The paper is based on 217 chemical analyses of the granitoid plutons grouped into five different geochemical suites (Shos - Shoshonitic, PKCAlk - Porphyritic K-Calc-Alkaline, EqKCAlk - Equigranular K-Calc-Alkaline, Alk - Alkaline and ChAlk - Charnockitic Alkaline). They are distinguished by petrographic and textural features, as well as Harker’s and geochemical discriminant diagrams. The Shosis easily distinguished from the others by its low silica content, while the Alk and ChAlk suites have high alkali contents. The PKCAlk and EqKCAlk show similar geochemical behaviour; but they can be separated mainly by petrographic and textural aspects. Field relationships and geochemical affinities suggested that the Shos, PKCAlk, EqKCAlk and Alk are approximately coeval, syntectonic plutons, whereas the ChAlk is interpreted as lateto post-tectonic as regards to the Brasiliano orogeny.

Palavras-chave


Seridó Belt; Brasiliano orogeny; Plutonism; Geochemistry; Discriminant diagrams.

Texto completo:

PDF (English)

Apontamentos

  • Não há apontamentos.