The Furnas/Ponta Grossa contact and the age of the lowermost Ponta Grossa Formation in the Apucarana Sub-Basin (Paraná Basin, Brazil): integrated palynological age determination

Abstract

The Furnas/Ponta Grossa Formation contact was until recently considered gradational or abrupt and of a Lochkovian to Pragian age in the Apucarana Sub-basin (Paran Basin, south Brazil). Based on sedimentology and palynomorph evidence a hiatus has been revealed between the Furnas Formation and the overlying Ponta Grossa Formation. The boundary between the topmost Furnas sandstones and the lowermost Ponta Grossa fine-grained sandstones constitutes a transgressive ravinement surface generated during a latest Pragian -early Emsian transgression. The hiatus corresponds to a maximum of ca. 4 Ma. A similar gap is also present in the Alto Garas Sub-basin.