Lithostratigraphy and volcanic facies architecture of the Paraná Continental Magmatic Province in its NE edge with the Alto Paranaíba Arch, Minas Gerais State, Brazil

摘要

In the NE edge of the Paraná Continental Magmatic Province (PCMP), compound pahoehoe, simple pahoehoe, rubbly flows, pillow lava, and simple pahoehoe/pyroclastic flows linked to ring structures with lithofacies associations have been identified. They belong to the Cretaceous Serra Geral Group. Intercalations of Cretaceous sedimentary deposits linked to the Botucatu Formation are common and can be of aeolian, alluvial, or, more rarely, lacustrine nature. These recurring intercalations indicate that volcanism and sedimentation occurred simultaneously and also attest to their intermittent nature. Geological characteristics of the study area - broadly dominant entablature structure, hypocrystalline basalts with quench textures, types of associated sedimentary deposits, and pillow lavas - support the idea that water was present during volcanic events, especially in the central portion. The recurrence of facies associations in the same stratigraphic section is discussed and is quite different from the stratigraphy that has been described for the south of the PCMP. A preliminary investigation using P2O5 content allowed the identification of five P2O5 basalt types. The distribution of these classes in the logs shows that elaborating a valid chemostratigraphic column for the region is not yet possible.