Geochemical variations in estuarine sediments: Provenance and environmental changes (Southern Spain)

The geochemical characteristics of the sedimentary infilling in the central basin of the Odiel River estuary have allowed the determination of the sediment provenance and the environmental conditions during the last 10,000 years. Thus, sediment provenance can be divided into three stages: (1) 9060e6500 years BP: the estuarine valley materials became the main sediment source because of intense erosion and sedimentation under transgressive conditions; (2) 6500e3200 years BP: the stabilization of the sea level and the current dynamic conditions involved an erosion of the Neogene and Quaternary formations that acted as sediment sources. At approximately 5705 cal. year BP, a high-energy marine event took place, suggesting that a tsunami could have affected this area; (3) 3200 years BP to present: the high sedimentation rate of the previous stage and the partial closure of the estuary, allowing the acid fluvial discharges from the Tinto and Odiel to reach the estuary and become the present main source of sediments.