Cretaceous to Recent tectono‐sedimentary history and subsidence of the Barreirinhas, Ceará and Potiguar Basins, Brazilian Equatorial Margin

Abstract

Stratigraphy along the Brazilian Equatorial Margin is a crucial guide to the geodynamic history of rifting of Pangea and formation of the South Atlantic Ocean. Understanding the evolution of the Brazilian Equatorial Margin, which intersects the Saint Paul and Romanche Fracture Zones on the western margin of South Atlantic Ocean, is also key for reconstructing eustatic histories and natural resource exploration. In this study, we quantify the stratigraphic and subsidence histories of three sedimentary basins—Barreirinhas, Ceará, Potiguar—that sit within the margin. Stratigraphy was mapped using ca. 900‐line‐km of two‐dimensional seismic data. Biostratigraphic and check‐shot data from 23 wells drilled on the continental shelf, slope and in the distal parts of these basins were used to date and depth‐convert stratigraphy. Check‐shot data were also used to parameterise compaction. The mapped stratigraphy was backstripped to calculate subsidence histories for the basins. Subsidence curves were decompacted, water‐loaded and corrected for palaeo‐water depths using biostratigraphic data from well reports. The mapped stratigraphy of the Barreirinhas and Ceará Basins and theoretical subsidence curves indicate that stretching factors did not exceed 1.6. These values suggest that these basins can be regarded as failed rifts. In contrast, more distal stratigraphy mapped in the Potiguar Basin to the south indicates that it stretched by a factor of 5–6. Calculated subsidence histories indicate that this basin formed primarily because of Cretaceous rifting and Cretaceous to Recent post‐rift thermal sag, with amplitudes governed by the amount of initial stretching.

The Tectonic Structure and Evolution of the Potiguar‐Ceará Rifted Margin of Brazil

“…The basement structure maps support local differences in the evolution of extension forming the segments of the margins (Figure 7). Further support comes from the slightly older age proposed for the unconformity above the units equivalent to Alagamar, that is, potentially related to cessation of tectonics and basin inundation, in Ceará and Barreirinhas to the north of Potiguar basin (Basilone et al., 2023). However, the age reported in other works for Ceará basin is not differentiated from Potiguar (Cerdeira et al., 2022; Maia de Almeida et al., 2020; Oliveira et al., 2020).…”

Lithofacies and Depositional Models of the Fine-Grained Sedimentary Rocks of the Albian–Turonian Stage in the Rio Muni Basin, West Africa

“…Its conjugate basin is the petroliferous Sergipe Alagoas Basin in Brazil [28,29]. The formation and evolution of the passive continental margin in West Africa can be subdivided into four major stages that are closely related to the opening of the Atlantic Ocean [33]. The Rio Muni Basin has also experienced a similar sedimentary evolution (Figure 2) [34,35].…”

“…(3) Drifting period (or thermal sag phase-Albian to present) Continued ocean accretion and continental drift led to the further opening of the South Atlantic [33,39,40]. The Rio Muni Basin entered the passive continental margin stage from this phase.…”