BIOSTRATIGRAPHIC ANALYSIS OF THE PELAGIC BARREMIAN APTIAN IN THE BETIC CORDILLERA (SOUTHERN SPAIN) - PRELIMINARY DATA

The Lower Cretaceous rhythmic sequences (marls and marly limestones) of the pelagic domain in the Betic Cordillera (Subbetic Zone) provide optimal conditions for integrated biostratigraphic scales based on different fossil groups. In this paper we present a preliminary study of the stratigraphic distribution of different species of ammonites, planktonic foraminifera, calcareous nannofossils and radiolaria recorded principally in one Barremian-Aptian section in Jaén (Andalusia, southern Spain). For the ammonites, which are present only in the Barrentian and probably in the lowermost Aptian, it appears reasonable to use the zonation proposed by Busnardo (1984) for SE France. Planktonic foraminifera can be differentiated in seven zones (Hedbergella sigali, Globigerinelloides blowi, Hedbergella trocoidea, Leupoldina cabri, Globigerinelloides algerianus, Planomalina cheniourensis and Ticinella bejaouaensis) for the Barremian-Aptian interval. Four interval zones (Lithraphidites bollii, Micrantholithus hoschulzii, Hayesites irregularis and Rhagodiscus angustus) can be distinguished according to the vertical distribution of the calcareous nannofossil species. Finally, two radiolarian assemblages can be identified, a lower one for the Barremian-Lower Aptian and an upper one for the Upper Aptian. Correlations between the scales used in this paper are established. © 1992.