Planktonic foraminifera from the Aptian section of the Southeastern Brazilian Atlantic margin

Upper Aptian planktonic foraminifera assemblages recorded in the post-salt section of the Santos, Campos and Espirito Santo Brazilian marginal basins are described and interpreted in terms of biostratigraphy and relative ages. The studied section represents the first marine sedimentary rocks deposited above the evaporitic sequence. Material from 26 Petrobras wells, including core, sidewalls and cuttings samples was analyzed. The upper Aptian planktonic foraminifera assemblages are composed mainly of cosmopolitan and chronostratigraphically long-ranging species, among which 22 species have been commonly recorded in the Tethyan Realm and other South Atlantic basins. Considering the biostratigraphic distribution, deposition of the studied section spans from the upper Aptian Globigerinelloides ferreolensis to Paraticinella rohri zones. Hence, the present study allowed the reassessment of the biostratigraphic framework, pointing out to an upper Aptian age for the marine section deposited immediately above the evaporitic sequence in the Santos, Campos and Espirito Santo basins. Indeed, a marine environment was established 5 to 10 Ma earlier than previously proposed. The reevaluation of the age constraints for the section provides new insight to the understanding of early South Atlantic Ocean geological evolution. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study describes and interprets the upper Aptian planktonic foraminifera assemblages in the post-salt section of the Santos, Campos, and Espirito Santo Brazilian marginal basins, providing insights into biostratigraphy and relative ages. The analysis of material from 26 wells reveals that the marine sedimentary rocks deposited above the evaporitic sequence are of upper Aptian age. This reassessment of the biostratigraphic framework suggests an earlier establishment of a marine environment in the studied basins, contributing to the understanding of early South Atlantic Ocean geological evolution.