The presalt Santos Basin, a super basin of the twenty-first century Rui Jorge Baptista, Andre Etienne Ferraz, Cristiano Sombra, Eugenio Vaz dos Santos Neto, Rafael Plawiak, Christiano Lopes Lops Silva, Andr  e Luiz Ferrari, Naresh Kumar, and Luiz Ant ^ onio Pierantoni Gamboa ABSTRACT The Santos Basin, offshore Brazil, is approximately 700 km in width and is probably the largest in area of the basins created by the breakup of the Gondwana supercontinent and creation of the South Atlantic Ocean. The crust underlying the basin was intensively stretched north of a major transform fault that affected both continents. Complex rifting within this highly stretched area created a broad marginal basin in the Santos sec- tor of Brazil not replicated on the African side. During the opening in the Early Cretaceous, volcanic features bounded to the south of the Santos Basin: Walvis Ridge, Rio Grande Rise, and the S~ ao Paulo Ridge. The segmented mid-ocean rift valleys developed as far north as the equatorial Atlantic. Organic-rich shales were deposited in lacustrine environments in the early rift valleys. These synrift shales became the primary source rock for the main hydrocarbon systems present in all the South Atlantic basins. As the separation between South America and Africa continued, shallow-water carbonates were deposited that were later covered by a thick layer of evaporites, creating excellent reservoirs and seals resulting in a prolific petroleum sys- tem revealed in 2006 by the supergiant Tupi field discovery. In the relatively shallower waters of the Santos Basin, other gas and light oil accumulations exist in Albian oolitic limestones and Upper Cretaceous turbidites. In addition to the synrift-sourced hydrocarbons, these younger accumulations also received sig- nificant contributions from the Cenomanian–Turonian marine shales. Copyright ©2023. The American Association of Petroleum Geologists. All rights reserved. Manuscript received April 5, 2022; provisional acceptance May 18, 2022; revised manuscript received June 8, 2022; revised manuscript provisional acceptance August 8, 2022; 2nd revised manuscript received August 15, 2022; final acceptance August 19, 2022. DOI:10.1306/04042322048 AAPG Bulletin, v. 107, no. 8 (August 2023), pp. 1369–1389 1369 AUTHORS Rui Jorge Baptista ~ Department of Geology, Faculty of Sciences, Universidade de Lisboa, Lisbon, Portugal; rjbaptista@fc. ul.pt Rui Jorge Baptista graduated from Universidade de Lisboa in 1979 as a geologist. He received his M.Sc. degree in 1987 from the Universidade de Lisboa and joined Petrogal SA in 1982. Formerly, he was exploration manager at Galp Exploration/Petrogal Brazil (1999 and 2013). After 2013, he became an adviser in the innovation department at Galp and is currently a visiting professor at the Faculty of Sciences at Universidade de Lisboa. He has been an active member of AAPG since 1986. Andre Etienne Ferraz ~ Department of Geology and Geophysics, Universidade Federal Fluminense (UFF), Niter  oi, Rio de Janeiro, Brazil; andreetienne@id.uff.br Andre Etienne Ferraz received a degree in geology from the Federal Rural University of Rio de Janeiro and master’s degree and Ph.D. in potential methods from the UFF. He has worked in prospecting for gold, base metals, and iron ore and in projects to define continental margin boundaries in Brazil and Africa. He currently works as a researcher investigating the geology of rift basins. Cristiano Sombra ~ Department of Geology and Geophysics, UFF, Niter oi, Rio de Janeiro, Brazil; csombra@id.uff.br Cristiano Sombra worked as a geologist at Petrobras from 1978 to 2021. His responsibilities included wellsite geologist, reservoir geologist, and exploration geologist in exploration and production assets and at the Petrobras Research Center. He received his M.Sc. degree in sedimentary petrology from the Federal University of Ouro Preto. From 2007 to 2020, he coordinated the technological program dedicated to the presalt production challenges. Cristiano retired from Petrobras in 2021 and is now a member of the research team at UFF.