Particle size and magnetic properties of Holocene estuarine deposits from the Doñana National Park (SW Iberia): Evidence of gradual and abrupt coastal sedimentation

Abstract

High resolution particle size and environmental magnetic analyses were carried out on two cores from marsh sediments in the Doñana National Park (SW Spain), in an investigation of gradual and abrupt coastal change. Complementary palaeontological analyses were also undertaken. Whilst the balance between sea level change and fluvial sediment input is seen to have a strong influence on the gradual evolution of the Guadalquivir estuary, via the development and degradation of spit barrier systems, two episodes of abrupt environmental change are recorded by the input of coarser sediment to the back-barrier. These episodes would appear to be associated with high energy conditions as a result of storm or tsunami events. The multi-disciplinary methodology presented here enables differentiation between these two episodes, the earlier of which (ca. 2400 yrBP) is probably due to a combination of enhanced erosion potential of the barrier and tsunami activity, and the later of which is the result of climatic instability during historical times (16th-18th centuries).