A combined micropaleontological, geochemical, and sedimentological study of the upper Aptian-Albian succession from the Sergipe basin, northeastern Brazil, has been undertaken. The paleoenvironmental evolution of the basin from the late Aptian to late Albian can be subdivided into three major depositional phases: (1) late Aptian, (2) early to middle Albian; (3) late Albian. A shallow carbonate compensation depth within upper mesopelagic depths (c. 300-500 m) is inferred for the late Aptian-Albian.

Intermittent anoxic events, associated with salinity-stratified water masses, occurred in the basin during the late Aptian to Albian. An oxygen minimum (dysaerobic to anoxic conditions) occurred during the late Aptian to earliest Albian, in middle-outer neritic to upper bathyal settings. Waning dysaerobic to oxic conditions are apparent in the late Albian.

The foraminiferal assemblages recovered from the upper Aptian marine deposits have a characteristic Tethyan affinity. The microfaunal evidence suggests that this area of the northern South Atlantic had at least some surface water exchange with low-latitude central North Atlantic-western Tethyan Provinces, even possible at intermediate (epipelagic to mesopelagic) water depths. Contribution of microfaunal elements coming from high-latitude northern (Boreal Realm) and/or southern (Austral) regions is also apparent, although of less significance.