Organic geochemistry and palynofacies of the Devonian: A correlation between Paraná and Parnaíba basins, Brazil

Abstract

A study on the characterization of the depositional paleoenvironment and the potentiality for hydrocarbon generation was carried out in Praguian-Emsian shale samples from Ponta Grossa Formation using data from organic geochemistry and palynofacies. The shales of the Ponta Grossa Formation presented contents of total organic carbon (TOC) with values up to 1.82%, poor to medium hydrocarbons source potential (S2), type II/III, III, and IV kerogen and they are immature to mature for hydrocarbons generation. These same data were correlated with studies of the Devonian (Givetian-Frasnian) of the Pimenteiras Formation, Parnaíba Basin. The results of the biomarker and palynofacies analyzes suggest a higher input of organic constituents of marine origin at the top of the studied sections of the Ponta Grossa Formation. This may be indicating early signs of sea level rise from a proximal to a more distal influence from the bottom to the top of these sections. These characteristics are also observed in the Middle to Upper Devonian (Givetian-Frasnian) of the Pimenteiras Formation (Parnaíba Basin), suggesting that the marine inflows that occurred in the Devonian began earlier in the Paraná Basin in relation to the Parnaíba Basin.