Calibration of the Early-Middle Pleistocene transition in the continental beds of the Guadix-Baza Basin (SE Spain)

The magnetostratigraphic and palaeontologic studies carried out in two sections in the Guadix-Baza Basin (SE Spain) have enabled an accurate calibration of the Early-Middle-Pleistocene boundary in the continental beds of this basin. The palaeontological record (rodents) in the Cortes de Baza-section indicates an age ranging from the earliest Pleistocene (latest Villanyian or early Biharian) to the late Early Pleistocene (late Biharian). The whole Cortes de Baza Section is placed in a reversed magnetic interval identified as the upper part of the Matuyama Chron. In the Guadix-Baza Basin, the Middle Pleistocene (early Toringian) was already known at the locality of Cullar-Baza I, but new studies in the area have resulted in the recognition of Early Pleistocene deposits in the lower part of the section. Thus, the locality of Cullar-Baza B is placed in a reversed magnetozone correlated with the uppermost Matuyama, while the locality of Cullar-Baza C is placed in a normal magnetozone correlated to the lower Bruhnes Epoch. Therefore, the Biharian-Toringian boundary (based on the presence of Arvicola cantiana) falls well within the Bruhnes epoch. This result is consistent with what is found in other Early-Middle Pleistocene sections of Spain (Atapuerca Gran Dolina).