Lithostratigraphic Review of the Cretaceous Cropping out Section in the Northern State of Alagoas, Sergipe-Alagoas Basin, Brazil

Lithostratigraphic, biostratigraphic and faciological criteria were established for the characterization and distinction of the sedimentary sections associated to the Maceió, Poção and Muribeca formations (Sergipe-Alagoas Basin), based on their occurrences in the northern region of the State of Alagoas. The Maceió Formation includes siliciclastic rocks with occasional evaporites (Paripueira evaporites) and basal limestones (Mundaú limestone), encompassing all strata equal to or older than those in palynomorph zone P-260, to the lower part of zone P-230. The Tabuleiro dos Martins Member is characterized by bituminous shales with intercalations of limestones, without any evaporite sections. The Poção Formation represents a conglomeratic section exclusive of the Alagoas portion of the basin, in particular along its border, interdigitated with the Maceió Formation, covering sections inserted in zones P-260 or lower, with a probable lower limit in zone P-220. Both units are limited at their top by the pre-neo-Alagoas unconformity. The Muribeca Formation consists of bituminous shales, limestones, evaporites, sandstones and conglomerates deposited over this unconformity and inserted in the palynomorph zones P-270 and P-280 (pars). The Carmópolis Member consists of coarse siliciclastics deposited immediately over the pre-neo-Alagoas unconformity. The Ibura Member is characterized by evaporites with intercalations of bituminous shales and dolomitic limestones. In Alagoas, it is represented by sections of anhydrite/gypsum, dolomite, and halite. The Oiteirinhos Member is characterized by shales with intercalations of limestones, sandstones, and siltstones. Based on stratigraphic, biostratigraphic, seismic and tectonic criteria, the classic outcrops of Japaratinga, Barreiras do Boqueirão and Morro do Camaragibe represent the Muribeca Formation, Carmópolis Member, differing from the current informal conception of belonging to the Maceió Formation, which possibly does not crop out.