Geoquímica orgânica e isótopos estáveis aplicados à caracterização de ambientes hipersalinos: estudos de depósitos Permiano e Aptiano-Albiano do registro geológico brasileiro

Abstract

Hypersaline environments have been attracting increasing interest in geosciences, both for exploring the occurrence of life under extreme conditions and for understanding new hydrocarbon exploration frontiers along the Brazilian Atlantic coast. Organic geochemistry techniques, such as biomarkers and stable isotopes, help investigate the metabolism of extremophiles and the evolution of the environments they inhabit. The geological record of these environments allows researchers to assess biota evolution over time under extreme conditions. This study analyzes selected Brazilian hypersaline environments due to their geological and economic relevance. First, it examines the Permian epicontinental sea (Irati-Whitehill), which once covered an area of 5 million km². During Gondwana’s geotectonic history, this sea became progressively enclosed, evolving into restricted high-salinity environments until its eventual continentalization and closure. Next, the study evaluates Aptian-Albian hypersaline environments associated with the first Tethyan incursions during the early South Atlantic opening. A detailed isotopic study correlated the Parnaíba Basin record with the global isotopic curve, identifying the OAE 1b global anoxic event in the Codó Formation. In addition to the tectonic regime, which created restricted hydrological settings, climatic factors may have contributed to the observed hypersalinity. Finally, the study discusses the implications of the first marine incursions into the Gondwanan equatorial environment (Codó Formation – Parnaíba Basin) and their possible connection with the salt deposits of the proto-South Atlantic Ocean, primarily recorded in the Campos and Santos basins.