Abstract Name: Riachuelo and Continguiba carbonate systems, Sergipe basin Authors: Eduardo A. M. Koutsoukos, Nivaldo Destro, Nilo C. de Azambuja Filho, and Adali Ricardo Spadini Location: From 9° to 11 ° 30' south latitude and 35° 30' to 37° west longitude, Sergipe, northeastern Brazil Geologic time interval: Middle Cretaceous, late Aptian–early Coniacian (Epicheloniceras sp-Diadochoceras sp.–Eodouvilleiceras sp. zone to the Solgerites armatus–Prionocycloceras lenti zone) Tectonic-sedimentary setting: Formed by a series of half-grabens with a regional dip averaging 10–15° to the southeast, resulting from normal faults arranged in a northeast-southwest direction Basin type: Atlantic-type passive marginal basin Paleoclimate: Dominantly dry, semi-arid, tropical Platform types: Mixed carbonate–siliciclastic system (late Aptian-Albian Riachuelo Fm.) and carbonate ramp system (Cenomanian–early Coniacian Cotinguiba Fm.) Platform geometry: Riachuelo carbonate system: average thickness of 500 m, but locally attains a maximum of 1700 m; about 20 km wide and 115 km long onshore. Cotinguiba carbonate system: thickness ranging from 200 m to over 1000 m locally in the onshore part; about 5–10 km wide and 200 km long onshore. Facies and fossils: Riachuelo Fm: oncolitic–oolitic–bioclastic packstone–grainstone; fine-grained limestone, marlstone, and shale; conglomerate, sandstone, and siltstone. Ammonites, planktonic and benthonic foraminifera, ostracods, radiolarians, algae, bivalves, brachipods, gastropods, serpulids, crustaceans, corals, echinoderms, and fishes. Cotinguiba Fm: rhythmic fine-grained carbonate mudstone, marlstone, shale, and wackestone breccia. Ammonites, nautiloids, planktonic and benthonic foraminifera, ostracods, radiolarians, diatoms, calcispheres, siliceous sponge spicules, bivalves, brachipods, gastropods, serpulids, crustaceans, cirripeds, corals, bryozoans, echinoderms, fishes, and reptiles. Systems tracts: lagoonal, neritic, upper bathyal, basin Stacking patterns: Not determined