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.
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2018
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The Serra Geral Formation belongs to the Paraná-Etendeka Magmatic Province (PEMP) and its geochemical and petrographic
characteristics are not homogeneous. Many studies segment this group into six basaltic and two rhyolitic magma-types. It is believed that its extrusion
occurred through crustal fissures in the Cretaceous, but some authors described the presence of conduits in the shape of basaltic ring structures (BRS) in
the Água Vermelha region in the North of the province. The BRS rocks, based on textures and structures, were divided into four groups—central flow,
basal flow, main ring dyke and lava flow—with a very similar petrography, composed of plagioclase (labradorite-bytownite), clinopyroxene (augite) and
oxide (titanomagnetite) with intergranular texture. The whole-rock analyses of the basal and lava flows allow classifying them as tholeiitic basalts of the
Paranapanema magma-type. Geochemical data interpretation suggests an enriched magma source, with low degree of partial melting, high depth of melt
generation and without significant crustal contamination. The BRS experienced fractional crystallization on shallow magma chamber, influenced by
successive new injections from different parental magmas which would be responsible for the pulses of effusion and explosion. Thus, the singularities of the
BRS of Água Vermelha are important to comprehend the evolution of the PEMP.
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lithochemistry, Petrography, Mineral chemistry
Citação
PACHECO, F. E. R. C. et al. 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. Brazilian Journal of Geology, v. 48, p. 283-304, 2018. Disponível em: <http://www.scielo.br/scielo.php?pid=S2317-48892018000200283&script=sci_abstract>. Acesso em: 08 fev. 2019.