Paleontologia e bioestratigrafia na transição Cenomaniano-Turoniano da área de Jardim, Formação Cotinguiba, em Sergipe

Abstract

The Sergipe-Alagoas Basin stands out for containing one of the most complete and well-exposed Cretaceous carbonate successions, associated with a rich and diverse ammonoid fauna. The main objective of this work was to carry out the identification, systematic description, and biostratigraphic interpretations of ammonoid mollusks (Class Cephalopoda) collected in the Jardim area, from the Cenomanian-Turonian interval (Upper Cretaceous) of Sergipe. Forty-six ammonoid specimens were identified and described from the Jardim 1, 2, and 5 localities, distributed into one family, four genera, and nine species: Watinoceras praecursor, Euomphaloceras costatum, Euomphaloceras sp. 1, Euomphaloceras sp. 2, Pseudaspidoceras flexuosum, P. pseudonodosoides, P. footeanum, Pseudaspidoceras sp., and Vascoceras gamai. This work records the first occurrence of Watinoceras praecursor in Sergipe. The studied fauna was assigned to two biozones: the Euomphaloceras septemseriatum Interval zone (upper Cenomanian), consisting of Euomphaloceras costatum, Euomphaloceras sp. 1, Euomphaloceras sp. 2, Pseudaspidoceras pseudonodosoides, and Vascoceras gamai, and the Vascoceras harttii Interval zone (lower Turonian), composed of Watinoceras praecursor, Pseudaspidoceras flexuosum, and P. footeanum. The biostratigraphic analysis of the ammonoid assemblages possibly indicates the Cenomanian-Turonian transition at the Jardim 1 locality. For a biostratigraphic refinement, systematic and detailed collections are suggested in stratigraphic sections that encompass the Cenomanian-Turonian transition. The analysis of the geographical distribution of the studied ammonoid species indicated mainly a Tethyan affinity.