Proposition for a new ammonite biochronology of the Albian series of the Andean Basin (Peru)

The study of the ammonite fauna of the Albian formations allows a major revision of its biostratigraphic frame in northern and central Peru. A carving in ammonite biozones is proposed for the Inca, Chulec and Pariatambo Formations and the Pulluicana group. The Lower Albian is represented by the Nicholsoni Biozone (subdivided into the umbilicostatus, and nicholsoni biohorizons, followed by an interval subzone) and by the Raimondii Biozone (carved in three subzones: Haasi, Raimondii – itself subdivided into the ebrayi and alternum biohorizons – and Mathewsi, including the pseudolyelli biohorizon). The Middle Albian is characterised by the Carbonarium Biozone, carved in the Ulrichi and Carbonarium Subzones. The base of Upper Albian is represented by the Cristatum Subzone.