The stra tigraphlc analysis of the Alagoas Stage (lo cal stage) in Ceará Basin allow s the investigat ed interval to be divided into two part s, with distinc tive tectono-sedimentary and paleobiological features. The lower part sho ws non-marine environmental character and the upper part , inforrnally named Ap tian-Albian tran sition, contalns marine organisms in certain leve is. These records would represent the Iirst phases of a primitive equatorial Atlantic Ocean in the area. The Trair! Beds at the to p of the continental sectio n were depo sited in an envirorunentaIcomplex which includes a marginal sabicha, reflecting cyclical conditions of extreme aridity or humidity. Similar events have occurred in the Potiguar Basin with the Ponta do Tubarão Beds and in Araripe Basin with the deposition of thinny calcareous and shale lay ers, here informaDy named "Batateira Beds". These environmental conditions provided an exce llent settlng fo r preservation of organic matter due to cyc lical anox ic processes. The observation that the organic extracts from shales of all these strata are similar supports the hypothesis o f correspondence of these events. Pctrobrás/ Cenpes (Rei. ín t .) .

An accurate biostratigraphic framework of the Cretaceous marine section of Campos Basin was established based on studíes of foraminifera, nannofossils, and palynomorphs. With the research of 77 wells it was possible to subdivide the Albian-Maastrichtian section in 11 zones of foraminifera,6 zones of nannofossils, and 7 zones of palynomorphs (the study ofwhich was restricted to the Albian-Santonían stages). Some of these zones remain still informal. Three main regional unconformities were found in the biostratigraphic sequence. These gaps correspond to the Early-Middle Cenomanían, Middle-Late Turonlan and Campanían. Less ímportant hiatuses were also found in the area.