Lithostratigraphy of a Cenozoic intra continental basin (Guadiana Basin, SW Spain) by using clay mineral assemblages and geophysical properties

•Mineralogy and geophysics used to describe depositional sequences of Guadiana Basin.•Illite, smectite + palygorskite and kaolinite enrichment image 3 depositional sequences.•Depositional sequences exhibit distinct electric resistivity imaging.•Data integration unravels Guadiana Basin formation and the role of Alpine tectonics. In the Iberian Peninsula, Alpine tectonics built several Cenozoic basins that were mainly filled with continental deposits. The Guadiana Basin is located halfway between two of the most important Cenozoic basins of the SW of Spain, the Tajo and the Guadalquivir basins. In this paper, both geophysical and mineralogical studies have been carried out in order to establish the lithostratigraphy of the Guadiana basin. A combination of electric resistivity properties and variations in clay mineral assemblage content of the basin infill was used to identify several depositional sequences within the Cenozoic deposits of the basin. Three depositional sequences, DS1, DS2 and DS3 characterized by differentiated clay content and mineral assemblages were distinguished. The lower depositional sequence, DS1, consists of reddish siltstones and clays that scarcely crop out in the basin. Clay content of the