Flow-by-flow chemical stratigraphy and evolution of thirteen Serra Geral Group basalt flows from Vista Alegre, southernmost Brazil

Abstract

The geochemical characterization of thirteen Serra Geral Group flows in the Vista Alegre region (RS-SC), southern Brazil, displays the homogeneous basaltic composition near 50 wt.

Geochemistry of basaltic flows from a basalt ring structure of the Serra Geral formation at Água Vermelha dam, Triângulo Mineiro, Brazil: implications for the magmatic evolution of the Paraná-Etendeka Province

“…This slight anomaly probably represents minor plagioclase fractionation. On the other hand, the Sr anomaly can be related to plagioclase fractionation, which is consistent with the presence of plagioclase phenocrysts and a glomeroporphyritic texture (Pinto & Hartmann 2011).…”

“…other samples of Paranapanema-type basalts, while the content of TiO 2 , K 2 O and P 2 O 5 stay constant with the increase of silica and it is significantly lower than typical Paranapanema. Also, they present enrichment of Al 2 O 3 MgO, CaO and Na 2 O related to other Paranapanema samples (Rocha-Júnior et al 2013, Machado et al 2007, Pinto & Hartmann 2011 (Fig. 15).…”

“…10B), and a negative Eu anomaly (Eu/ Eu* = 0.85-0.94). When those analyses are compared to Pinto & Hartmann (2011) data for the Paranapanema type (gray field on Fig. 10B), the patterns are very similar.…”

“…However, the average composition of the Água Vermelha basalts shows some differences from the average composition of other Paranapanema rocks, with slightly lower contents of SiO 2 , TiO 2 , Fe 2 O 3 , K 2 O and P 2 O 5 and higher contents of MgO, CaO and Na 2 O compared to the samples from Rocha-Júnior et al (2013), Machado et al (2007) and Pinto & Hartmann (2011) (Fig. 11).…”

“…Gray field represents the Paranapanema type basalts, with data from Pinto & Hartmann (2011). (C and D) Incompatible elements normalized to midocean ridge basalt (MORB) (Sun & McDonough 1989) …”