Gravitational landslides in the Upper Miocene of the Guadalquivir Basin (SW Spain)

The Guadalquivir Olistostrome Complex is a chaotic mixture of Subbetic related lithologies. Where it reaches more than 500-600 m of thickness, the olistostrome becomes an insurmountable shield for seismic surveys due to its internal disorganization. This situation happens regionally at the centre and South of the Betic foreland basin where it reaches the surface. The previous studies bibliographic data usually map differently a single underground northern front and the southern line up of outcrops. However; some seismic lines allow us to distinguish some indentation at the subterranean front, suggesting that at least three episodes of gravitational slides happened probably during the upper Tortonian, the Tortonian-Messinian and the Messinian. These episodes developed different types of stacking (forestepping or backstepping) varying along the strike of the Guadalquivir basin. The landslides occurred in a short period of time, but they occurred firstly in the NE sector of the basin, which is in agreement with the postulated collision of the Alboran Domain during the Burdigalian. It started from the East and leaded to the great structural deformation of Mesozoic and Cenozoic rocks in the South Iberian margin. The causes that produced their glide, their homeland, the travel speed and their correlation whit the outcrop is open to discussion.