Geochemistry of mafic dykes of Brumado, southeastern portion of Gavião Block, Bahia, Brazil
DOI:
https://doi.org/10.11606/issn.2316-9095.v19-144710Keywords:
Lithogeochemistry, Petrography, Mafic dykes, Gavião Block, MantleAbstract
In the southwest of the state of Bahia, between the cities of Brumado and Caetité and further north near the cities of Tanque Novo, Paramirim, Botuporã, Macaúbas, Novo Horizonte and Ibitiara, there are mafic dykes formed in an intraplate environment. These continental tholeiites with magnesium differentiation index values (mg#) between 0.25 to 0.45, indicative of evolved magmatic liquids. Plagioclase and augite are predominant phases in the magmatic evolutionary process, whose diagrams show no significant alterations by secondary processes. The mafic dikes originated from a somewhat heterogeneous Enriched Mid-Ocean Ridge Basalt (E-MORB) source, probably with a slight contribution of Ocean Island Basalt (OIB) fluids. The geochemical data suggest a significant influence of the inferior continental crust on the origin of the mantle source, with no signs of significant sedimentary contribution.
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