Stratigraphic evolution from the early Albian to late Campanian of the Potiguar Basin, Northeast Brazil: An approach in seismic scale

Abstract

AbstractFive 3rd‐order depositional sequences are interpreted from the early Albian to late Campanian interval in the Potiguar Basin. An integrated analysis of seismic interpretations, well logs, cores and biostratigraphic data provides a stratigraphic framework composed by stratigraphic surfaces, systems tracts and sequences. Depositional Sequence 1 and 2 are, respectively, Albian and early to mid‐Cenomanian aged and are composed by the falling stage, low stand, transgressive and high stand systems tracts. Depositional Sequence 3 is late Cenomanian to mid‐Turonian aged and is composed by the transgressive and high stand systems tracts. Depositional sequences 4 and 5 are, respectively, late Turonian to mid‐Santonian and late Santonian to mid‐Campanian aged and are composed only by transgressive and high stand systems tracts. The lack of falling stage and low stand systems tracts in depositional sequences 3, 4 and 5, as well the increasing in transgressive and highstand systems tracts thickness as depositional sequences get younger, are reflection of an overall transgressive trend of a 2nd‐order sequence. The interpretation proposed in this paper correlates onshore with offshore deposits within a seismic scale (3rd‐order) sequence stratigraphy framework. This approach allows a better understanding of the Açu Formation, the primary oil‐bearing formation of the Potiguar Basin. The Açu Formation is part of depositional sequences 1, 2 and 3 and is characterized by lateral and vertical variations of depositional systems instead of being associated to a specific depositional system. This sequence stratigraphy analysis can be used as a low‐resolution framework for future high‐resolution (4th‐order scale) studies.