Comprehensive Assessment of Petroleum System Evolution in The Sedimentary Basins of The Atlantic Margin, Brazil (Santos, Campos, Pelotas)

Summary The research area is confined to the modern continental slope of the Atlantic Ocean (the shelf of Brazil). A study of the history of the geological development of the east coast of South America has shown that the Pelotas basins, as well as the Santos and Campos basins, have developed differently since the Aptian period, which is reflected in the differences in their structure. The decisive factor in the formation of the modern appearance of the northern basins is large-scale halokinesis, which continues to the present day. The study examines the main stages of the development of the region with a detailed description of the evolution of hydrocarbon systems. In total, there are 3 stages: rift (accumulation of the main source lake layer), post-rift (formation of carbonate rifs and accumulation of evaporites), passive-marginal (final formation of the modern appearance of the continental margin, accumulation of terrigenous deep-water complexes, halokinesis). The main geological factors that determined the oil and gas content of the Santos and Campos basins are the presence of a regional parent rock associated with the synrift complex of sediments, a thick evaporite layer (regional fluid barrier), and the processes of halokinesis that form positive structural forms. The Pelotas basin is characterized mainly by stratigraphic and lithologically-shielded traps associated with the wedging zone and deep-sea turbidite deposits. The development of thick volcanoclastic formations has significantly reduced the areas of accumulation of lacustrine source matter, similar to the Santos and Campos basins.