Portal de Periódicos da CAPES

Artigo Acesso aberto Produção Nacional Revisado por pares

BIBTEX RIS

Stratigraphic Relations of the Ipubi Formation: Siliciclastic-Evaporitic Succession of the Araripe Basin

2018; Brazilian Academy of Sciences; Volume: 90; Issue: 2 suppl 1 Linguagem: Inglês

10.1590/0001-3765201820170526

1678-2690

CARLOS E. FABIN, Osvaldo José Correia Filho, Márcio Lima Alencar, José Antônio Barbosa, Tiago Siqueira de Miranda, Virgínio Henrique de Miranda Lopes Neumann, Igor Fernandes Gomes, Felipe Ribeiro de Santana,

Geology and Paleoclimatology Research

The Ipubi Formation represents the Aptian-Albian siliciclastic-evaporitic succession of Araripe Basin, NE Brazil. This succession comprises siliciclastic rocks (bituminous shales and claystones) and evaporites (gypsum and secondary anhydrite) and represents part of the lacustrine-shallow marine post-rift phase I. This study used sequence stratigraphy concepts to define the relations between changes in the relative lake level and the formation of Ipubi deposits. Results show that the organic-rich shales of the Ipubi Formation formed during a transgressive pulse that covered large areas of the proximal domains. These deposits overlie a regional unconformity that marks the end of the deposition of the underlying Crato Formation. A High Stand stage that followed the transgression influenced the formation of evaporitic deposits. Climate conditions played a major role in influencing the triggering and stopping of evaporite deposition. Thus, a new relative lake level fall event caused the exposure of the Ipubi Formation deposits, and created another regional subaerial unconformity accompanied by widespread karstification of evaporite beds. A posterior transgression caused the deposition of siliciclastic rocks of the Romualdo Formation over the Ipubi Formation strata, and also promoted a new event of karstification of the Ipubi upper evaporite beds.