PALEOGEOGRAFIA DA SEÇÃO CRETÁCEA NEOAPTIANA DO NORDESTE DA BACIA DE SERGIPE-ALAGOAS, BRASIL

Cretaceous Late Aptian paleogeography from Northeastern Sergipe-Alagoas Basin, Brazil

Abstract

The late Aptian section of the Sergipe-Alagoas Basin includes the initial marine transgressions records effectively responsible for the South Atlantic Ocean implantation by the end of the Cretaceous. Better known in its southern portion (Sergipe Sub-basin), the behavior of these transgressions is still poorly understood in the northeast portion of the basin (Alagoas Sub-basin). Based on the integrated analysis of biostratigraphic and faciological data from wells and outcrops, this study presents lithostratigraphic maps and paleogeographic reconstructions for two time intervals. They both mark the transition between essentially continental depositional sequences (K40; Early–Late Aptian) for those whose characteristics depositional systems were predominantly marine (K50; Late Aptian). Although separated by an important unconformity, called pre-neo-Alagoas, the reconstructions permitted to observe that the depositional processes were, in a way, much similar to the stratigraphic units below and above this unconformity. The differences are evidenced by the transgressive K50 behavior, which would have taken advantage of the same more subsided compartments of the K40 sequence. Coincidentally, these same compartments would again be the target of later transgressions, in the Cenomanian and between the Danian and Ypresian.