Zonal scales of brachiopods, foraminifera, ostracods and palynomorphs from the Lower/Middle Jurassic transition in the Iberian Peninsula: calibration with ammonoid zones

Abstract

The aim of this work was to synthesize all the data obtained over the last four decades by the various researchers who have formed part of the multidisciplinary Jurassic research group founded by Professor Antonio Goy. This is, therefore, a review that seeks to integrate data from various studies on different fossil groups in the Iberian Peninsula during the transition from the Early to the Middle Jurassic. The boundary between the Early Jurassic and Middle Jurassic in the Iberian Peninsula is represented by alternating calcareous and marly levels containing abundant fossils of benthic, planktonic, and palynomorphic organisms. Among all of these, the ammonoids offer the best high-resolution biostratigraphy. A detailed review of the ammonoids zonal scales established in the Iberian Peninsula (Iberian Cordillera, Betic Cordillera, Basque-Cantabrian Basin and Lusitanian Basin) has been carried out. Besides, the ammonoid scales defined in the different areas of the Iberian Peninsula have been compared with the standard zonation for northwestern Europe and with the Mediterranean zonation based on the hammatoceratid group, defined in the Betic Cordillera. All these ammonoid scales have been calibrated with established regional scales using brachiopods, foraminifera, ostracods, palynomorphs, and biofacies samples to highlight which species are useful for establishing correlations within the Iberian Cordillera and with other basins in the western Thetys.