The Piraçununga Formation in the Vargem Grande do Sul region, São Paulo. Application of the technique of sedimentary profiles

Abstract

The informal name of Vargem Grande do Sul is here proposed for the psamopelitic lithofacies ofthe supposed Oligocene-Miocene Piraçununga Formation outcropping in the São João da Boa Vista area. This facies is interpreted as an alluvial plain deposit probably related to fault tectonism. A new unit, the Leme facies, is also proposed for the coarser sediments of the Piraçununga Formation - laid down at the same time or later as a higher level. Based on plant and insect fossils, Oligocene-Miocene age is attributed to the Vargem Grande do Sul facies in the lower part of the formation. This age cannot surely be generalized for the whole formation.