Temporal variability of flooding events of Guadiana River (Iberian Peninsula) during the middle to late Holocene: Imprints in the shallow-marine sediment record

• Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
• Main Authors: Mendes, Isabel, Lobo, Francisco J., Hanebuth, Till J. J., Lopez-Quiros, Adrian, Schoenfeld, Joachim, Lebreiro, Susana, Reguera, Maria, I, Anton, Laura, Ferreira, Oscar
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2020
• Subjects: Gulf of Cadiz; Climate dynamics; Mud depocenter; North Atlantic Oscillation; Benthic foraminifera; XRF element ratios; Physical Geography; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10400.1/16360; https://doi.org/10.1016/j.palaeo.2020.109900

Sedimentological, geochemical and benthic foraminiferal proxies were used to interpret changes of depositional environments in a mud entrapment inside the Guadiana River paleo-valley, northern Gulf of Cadiz, to understand the temporal variability of fluvial flooding events and to detect patterns of latitudinal climatic variability in western Iberia. The period between ca. 5800 and ca. 1250 cal yr BP was characterized by slowly accumulating coarse-grained sediments, high content of biogenic sand components, and high abundances of shallow-water benthic foraminiferal species. After ca. 1250 cal yr BP, the sedimentary environment was dominated by fine-grained sediments, with high abundances of opportunistic benthic foraminiferal species and successful colonizers, and high values of geochemical ratios indicative of enhanced terrigenous supply. Sedimentation rates increased drastically over the last ca. 500 years. The genesis of these environments was mainly driven by the variable frequency of fluvial flooding events driven by the regional climate variability. Low terrigenous sediment input under dry conditions prevailed in the older sedimentary unit. Flood frequency and terrigenous sediment supply increased during the younger unit. The variability of the North Atlantic Oscillation at centennial scales highly influenced the sediment supply during the last ca. 500 years, with high terrigenous supply during negative NAO conditions. Our results corroborate an N-S gradient along the Atlantic Iberia during middle and late Holocene, with more humid conditions in the northwestern and drier conditions towards the southeast. The gradient weakened over the past ca. 500 years, with increased rainfalls and flood events during the Lithe Ice Age. Portuguese Science Foundation (FCT)Portuguese Foundation for Science and Technology [UID/0350/2020 CIMA] Spanish Ministry of Economy and Competitiveness [CGL2011-30302-C02-02, CTM2017-88237-P] FCTPortuguese Foundation for Science and TechnologyEuropean Commission ...