PRIMEIRAS OBSERVAÇÕES DA FORMAÇÃO PITANGA (GRUPO SERRA GERAL) NO ESTADO DE SÃO PAULO

The basalts of the Serra Geral Group in the central-eastern region of São Paulo, including Brotas, Jaú, Araraquara, Ribeirão Preto, and Serro Azul, cover ~14,210 km² of basaltic flows and sills. This study aimed to characterize the Pitanga Formation through volcanic facies, petrography, and geochemistry, contributing to understanding the magmatic evolution of the northern Paraná Basin. Field campaigns, drill-core logging, petrography, and X-ray fluorescence analyses were conducted on 94 samples. Geochemical results indicate high-titanium (ATi) basalts of the Pitanga-type magma, with TiO₂ from 2.82% to 4.5%, SiO₂ 48.04–54.42%, MgO 2.57–5.6%, and P₂O₅ 0.28–0.79%. Binary diagrams reveal well-defined trends, with greater variation in intrusive bodies. Trace elements include Sr (376–613 ppm), Ni (3–124 ppm), Cr (55–142 ppm), Rb (9–48 ppm), and Zr/Y ratios from 4.68 to 7.27. Field observations show tabular flows with “p”-type pāhoehoe lobes at the base, overlain by entablature lavas with inflation structures. Lobe rupture by water generated upper breccias, sometimes associated with peperites. Columnar basalt is holocrystalline (plagioclase ~50%, clinopyroxene ~30%), whereas entablature is aphyric with glassy mesostasis (~50–70%), amygdaloidal and diktytaxitic. These data indicate a dynamic environment in the semi-arid northeast portion of the Serra Geral Group, where water or vapour influenced cooling and facies development. Integrating geochemistry with facies architecture allows for detailed characterization of the Pitanga Formation and insights into the evolution of the Serra Geral Group.