Carbon isotope curves for the Early Cretaceous pre-Salt section of Gabon are compared to similar curves globally. Major 13C excursions in the Gabon pre-Salt can be correlated with similar events globally.
In the past the ages assigned to the pre-Salt strata of Gabon have been highly generalised. The curves presented in this paper allow some accurate ties to be established between the pre-Salt and standard chronostratigraphic stages.
The onset of salt deposition at this palaeolatitude can be accurately defined as close to the Early/Late Aptian boundary.
For biostratigraphers, one of the most significant palynological events in the pre-Salt section of this region is the downhole increase in Dicheiropollis etruscus. Previously this has been assigned a general Barremian/Neocomian age. Comparison with the 13C curve suggests this event is Early Hauterivian. Interestingly, this compares well with data from marine Early Cretaceous sections further north along the Atlantic margin, where the downhole increase of Dicheiropollis etruscus is seen within the Hauterivian stage as defined by Tethyan dinocyst ranges.
Carbon isotope analyses from the Gabon pre-salt section have enabled the accurate stratigraphic assignment of an important palynological event for the first time.
Nick Miles
The combination of palynology and ostracod biostratigraphy with carbon isotope stratigraphy has provided age constraints on the timing of salt deposition offshore Gabon and provides additional constraints for the timing of opening of the South Atlantic.
Marcus Jakeman
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James S. Eldrett a, Steven C. Bergman, Christian Heine, Paul Edwards, Marcus Jakeman,
Nick Miles, Bastian Hambach, Steven M. Bohaty, Megan R. Wilding. Integrated bio- and chemo-stratigraphy for Early Cretaceous strata offshore Gabon: Additional constraints on the timing of salt deposition and rifting of the South Atlantic. Marine and Petroleum Geology, 148 (2023). https://doi.org/10.1016/j.marpetgeo.2022.106037.
