DIVISÃO ESTRATIGRÁFICA DO MESOZOICO NO ESTADO DE SÃO PAULO

PAULO CÉSAR SOARES

Resumo


The Mesozoic of the Paraná Basin in São Paulo State admits a division in four formations: Pirambóia, Botucatu, Serra Geral and Bauru. The Pirambóia Formation, as defined in this paper, exhibits a maximum thickness of more than 300 m in the central part of the State, reducing towards the Ponta Grossa arc (South) and towards the northeast basin boundary. This Formation is composed of various cycles, represented by channel deposits succeded by overbank deposits. It consists essencially of very fine to medium grained muddy sandstones with great textural uniformity and single mineralogical suite. These characteristics reflect great intensity of reworking'of the material furnished to the basin. The Botucatu Formation is constituted by sediments of desertic environments: very fine to fine grained eolian sandstones with good sorting, cross stratification of medium to great width; locally conglomeratic sandstones, deposited by wadis; and rarely muddy sandstones and mudstones, settled down on lakes. The Serra Geral Formation embodies basaltic flows and at the lower part intertongues with the Botucatu sandstones. The Bauru Formation is composed, of fluvial sandstones and mudstones, and fluvio-lacustrine calcareous sandstones, with basal conglomerate, over an erosional unconformity sculptured on basalts, and, locally, sandstones. The boundary of the Mesozoic and Paleozoic sequences in the São Paulo State is an unconformity sculptured on rocks of different ages. In the Rio Grande do Sul State, deposits correlated to the Pirambóia Formation are denominated Rosario do Sul Formation, which embodies the Santa Maria beds (Late Triassic). The upper part of the Botucatu Formation is contemporaneous to the Serra Geral basalts (late Jurassic-early Cretaceous). Thus, the age of the Pirambóia Formation is Middle Triassic to Jurassic and of the Botucatu Formation is Jurassic.

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