Holocene aeolian dunes in the National and Natural Parks of Doñana (SW Iberia): Mapping, geomorphology, genesis and chronology

The dune fields of the National and Natural Parks of Doñana are considered one of the most outstanding dune fields in Western Europe. They are located at the west margin of the Guadalquivir river estuary. The accumulation of aeolian sands partly blocks the connection between the ample Guadalquivir River estuary and the Gulf of Cádiz in the Atlantic Ocean. The sand units form a large oval dome, the “Abalario Dome” which connects with the large Doñana Spit Bar where dune systems accumulated as well, at least in part coevally with the spit growth. The most frequent dune morphologies are parabolic or transverse. The degree of activity was classified as stable, semi-active and active. Most stable dunes concentrate on the Abalario Dome, whereas active dunes occur mainly on the Doñana spit bar. Relative chronology was established from the superposition of dune Systems and Subsystems deduced from photogeology coupled with field surveys, orthophotos, and oblique and 3D images. Sampling and radiogenic dating (Optically Stimulated Luminescence-OSL) allowed to date eight dune Systems named as Systems I to VII plus an additional CS, which is a laterally equivalent to part of S IV, V and VI. The proposed ages are: System I, age 11.1 38 to 9.5 ky BP, perhaps extending to 8.5 ky BP. System II, 8.2 to 6.1 ky BP. System III, 5.9 to 2.6 ky BP. 39 System IV, 2.6 to 1.6 ky BP. System V, 1.6 to 1.3 ky BP. System VI, 1.2 to 0.7 ky BP. System VII, 0.7 to 40 0.15 ky BP. The age of the Complex System is 2.2 to 0.15 ky BP. Additionally, it was concluded that genesis of the somewhat-different Complex System (CS) was related to the increased accumulation space created by movements (sliding) along the Mazagón and Torre del Loro faults following major regional seismic activity