Integrated biostratigraphy (calcareous nannofossils, planktonic foraminifera, and radiolarians) of an uppermost Barremian–lower Aptian pelagic succession in the Subbetic Basin (southern Spain)

Abstract

An integrated study of the calcareous nannofossils, planktonic foraminifera, and radiolarians is provided for the uppermost Barremian–lower Aptian succession of the La Frontera area, located in the pelagic domain (Subbetic Zone) of the Betic Cordillera. This succession encompasses the Early Aptian Oceanic Anoxic Event 1a (OAE 1a) and has also been previously studied for bulk-rock carbon isotopes. Moderate to good preservation of calcareous and siliceous plankton allowed the identification of several bioevents, which are calibrated with respect to the carbon-isotope stratigraphy. The stratigraphic succession was dated by applying previously well-established zonation schemes for calcareous nannofossils, planktonic foraminifera, and radiolarians, which are integrated with the stable carbon-isotope curve. The proposed integrated litho-, bio- and chemo-stratigraphy, derived from direct calibration, provides an accurate and consistent scheme for the correlation and for the timing of sedimentary processes that affected the Subbetic Basin during the OAE 1a episode. Correlation using planktonic foraminifera and nannofossil data provide links between the La Frontera succession and other early Aptian reference sections in the Betic Cordillera, in the Tethyan, and in the Boreal realms.