Análise faciológica frente ao controle paleoambiental baseado na palinologia do intervalo Aptiano/Albiano da Bacia do Araripe (Sub-bacias Cariri e Feira Nova), NE do Brasil

Abstract

The Aptian-Albian Stage represents an important stacking in the understanding of the final stage of tectonic organization of the Araripe Basin. On the other hand, this interval is exhaustively analyzed in the quest for the paleoenvironmental understanding of this basin, as is the case of the Santana Formation, with a faunal / floristic macrofossil content, and the Barbalha Formation constituted by sediments deposited in the fluvio-lacustrine environment. Aiming at the addition of information that may contribute to the understanding of the dominant faciological features in the Aptian-Albian Stage, as well as palynophoretic conditions, the present work presents an analysis of columnar sections raised around the Araripe Basin, in which it was made an analysis High-resolution faciology corroborated with information obtained from the palynological content collected at the pelitic levels of the Barbalha and Santana formations, in the Eastern (Cariri Sub-basin) and Western (Feira Nova Sub-basin) sectors lacking micropaleontological studies. The Barbalha Formation presented a typical faciology of braided fluvial environment associated to lacustrine environment, even presenting a representative maximum flood level (Camadas Batateira) and tracked in all the columnar sections raised for this unit. In turn, the Santana Formation is the predominance of low energy depositional systems, initiated by carbonate-pelitic levels (Crato Member) , superimposed by evaporites and shales. In the SW sector of the basin, the evaporites (Ipubi Member) are thicker than those observed in the N/NE sector, related to the direction of the marine entry, which happened from south to north, following a opposite way to the fluvial paleocurrent of the Santana Formation, those marine transgressions are confirmed by the presence of palinoforaminifera and dinoflagellates. The Romualdo Member top indicates the return to the fluvial conditions, closing a transgressive / regressive cycle acting in the Aptian-Albian gap of the Araripe Basin. The sporo-pollinic content found indicates a predominance of hot climate, showing a variation of environmental conditions from semiarid to arid, along the sections, being correlated with the Sub-zone P-270 of Regali & Santos (1999).