Early Cretaceous ostracod biostratigraphy of eastern Brazil and western Africa: An overview

Abstract

Petroleum exploration in the offshore basins of eastern Brazil and western Africa has been aided for the last fifty years by an understanding of the Early Cretaceous ostracod biostratigraphy of the proto-South Atlantic. This review charts the development of the presently accepted zonation from its early development in the RecÔncavo-Tucano Basin and recognition as palaeontological evidence for continental drift in the 1960s, to its application over the following five decades in the Brazilian Sergipe-Alagoas, Araripe and Campos basins and the western African Congo, Gabon and Kwanza basins. The distribution of ostracod species in the lakes which formed during the early stages of the opening of the Atlantic during the Early Cretaceous was often extensive, and this has resulted in effectively South Atlantic-wide application for many species, and certainly for the zonation as a whole. Indeed, petroleum companies continue to exploit the predictability of the ostracods in South Atlantic operations due to the fact that they are often able to provide accurate constraints on stratigraphic position for a relatively low cost. However, the ostracod biozonations of the pre-Salt section for several eastern Brazilian basins, such as the RecÔncavo-Tucano, Sergipe-Alagoas and Campos, have not been thoroughly revised since the 1980s, and the taxonomy of these remains somewhat outdated. Furthermore, ostracod biozonations for many basins on both coasts (e.g. the Brazilian Espírito Santo and the western African Namibe basins) have never been published. An updated and revised taxonomy of the ostracods of the basins of eastern Brazil and western Africa is presented (Appendix I), as well as a revision of the biozonation on both sides of the modern day Atlantic Ocean. It is hoped that this paper will act as a catalyst for further work in the basins surrounding the modern day South Atlantic, which hold much interest for petroleum companies and micropalaeontologists alike. © 2012 International Association for Gondwana Research.