Stratigraphy of the Post-Rift Sequences of the Jatobá Basin, Northeastern Brazil

Abstract

The sedimentary infill of the Jatobá Basin is not well known, belying its importance in relation to other interior rift basins of northeastern Brazil. In its northern portion, and particularly in the middle to the top of Serra Negra and the Periquito hills, outcrops of laminated limestones interbedded with terrigenous sediments are found, which have been correlated by da Rocha and Leite (1999) with the Aptian laminated limestones of the Crato Formation (Santana Group, Araripe Basin) (Neumann and Cabrera 1999). Among the intracratonic basins of northeastern Brazil, the Jatobá Basin presents a succession of lacustrine sediments with pronounced phases of deltaic siliciclastic influence similar to the Aptian lacustrine phase of the Araripe Basin (Neumann et al. 2003). The Crato Formation of Jatobá Basin presents very similar lithology, fossil content, age, and depositional environment to those of the Paracuru (Ceará Basin; Neumann et al. 2009), Codó (Paranaíba Basin; Bruni et al. 1976), and Crato (Araripe Basin; Neumann et al. 2009) formations. The Aptian lacustrine infill is both a generator and reservoir of oil in the Atum and Xaréu oilfields in the Ceará Basin. Given these various points, it is important to determine the geological evolution of the post-rift stratigraphic sequence of the Jatobá Basin. Therefore, the main objective of this work is investigate the post-rift sequence of the Jatobá Basin, focusing on its subdivision into two units: post-rift I (Marizal, Crato, and Romualdo formations), and post-rift II (Exu Formation). The results will contribute to establishing a new lithostratigraphic scheme for the Jatobá Basin, and will also inform studies of other lacustrine systems of intracratonic basins in northeastern Brazil.