Kaolinitic paleosols in the south west of the Iberian Peninsula (Sierra Morena region, Spain). Paleoenvironmental implications

This paper studies the physical and chemical characteristics of eight different soil profiles with paleohorizons rich in kaolinites and developed on different lithologies along the southern border of the Hercinian Iberian peninsula (Sierra Morena region).The paleohorizons of four of these soils are defined by low pH levels, desaturation of the exchange complex and proportions of kaolinite of over 75%; these characteristics are associated with subtropical pedogenic conditions during the Pliocene period.A further two soil profiles are contemporary and defined by the following features: they occupy depression areas, the clay fraction is dominated by kaolinites and smectites, the exchange complex is saturated and the pH is above neutral values.The last two soil profiles are developed on Pliocene continental deposits and have more moderate pedogenic features, their kaolinite levels are around 50% and their evolution is associated with shorter periods of exposure to these subtropical alteration conditions.