Ostracodes da formação santana (cretáceo inferior, aptiano superior), bacia do Araripe, NE-Brasil : taxonomia, distribuição estratigráfica e paleoecologia

AUTOR(ES)

Lucas Silveira Antonietto

DATA DE PUBLICAÇÃO

2010

RESUMO

Thirteen ostracod species were recovered from samples in sections of drillings IPS-11 IPS-CE and IPS-12-CE, Crato and Romualdo members, Santana Formation: Harbinia alta, Harbinia crepata, Harbinia micropapillosa, Harbinia salitrensis, Harbinia symmetrica, Cetacella edrianae sp. nov., Talicypridea? sp.1, Talicypridea? sp.2, Paracypria sp.1, Ilyocypris sp.1, Darwinula? Sp.1, Gen. 1 et sp.1 and Gen. 2 et sp.1. The species associations and clusters allow correlation of the Alagoas Stage in the Araripe basin with several others in the Brazilian continental margin: Espírito Santo, Grajaú, Maranhão, Potiguar and Sergipe-Alagoas. Additionally, this interval can be correlated to the upper Aptian of the basins of Gabon, Congo and Angola, in the African western continental margin. Species associations and clusters are in general limnic, monospecific and largely dominated by species of Harbinia, an evidence of paleoenvironments dominated by brackish to hypersaline lakes. Cetacella, a genus associated to carbonate environments, occurs in one limestone sample of in the Ipubi layers. Occurrence of Ilyocypris and Paracypria in the Romualdo Member indicate freshwater to oligohaline intervals; additionally, the occurrence of Paracypria indicates transitional environments. According to the analysis of the studied sections, as well as previous works, sediments from the Crato Member, in particular the Ipubi layers, and the basal section of the Romualdo Member were deposited in transitional environments composed by coastal lakes. These lakes presented salinity levels ranging from hypersaline in the Crato Member to freshwater until brackish in the Romualdo Member, with prevalence of low-energy environmental conditions and eventual episodes of high energy.

ASSUNTO(S)

andar alagoas taxonomia distribuição estratigráfica lower cretaceous alagoas stage taxonomy palaeoecology cretáceo inferior geologia stratigraphic distribution paleoecologia

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