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Guadalfeo and Adra submarine deltas evolution in response to sediment supply variations
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Resumo(s)
The Guadalfeo and the Adra submarine deltas off the northern coast of the Alboran Sea have been built up under the direct influence of short and mountainous rivers. The area is subjected to strong climatic seasonality, with sporadic winter torrential floods and high summer aridity. In addition numerous anthropogenic activities have affected these systems, mostly during the last two centuries. In order to decode the influence of climatic variability and anthropogenic impacts on sediment supplies during the recent past, five sediment cores were collected from the Guadalfeo and Adra submarine deltas. Benthic foraminiferal and sedimentological analyses, combined with radiocarbon dating, were performed.
The impact of torrential floods alternating with periods of low rainfall or dry periods were recorded in the Adra and Guadalfeo prodeltas. Periods with low abundance of benthic foraminifera and high amounts of coarse-grained sediments, were interpreted as the result of enhanced sediment supply to the shelf triggered by major flood events. On the other hand, periods with high amounts of fine-grained sediments and high abundances of colonizers and opportunistic foraminiferal species indicate the establishment of new environments with distinct ecological constraints. These environments were driven by lower sediment supplies during low rainfall or dry periods. The most recent sedimentation seems to reflect the human interventions in the rivers basins, such as deviation of the main river courses and dams construction, which reduced the sediment input and promoted the deposition of shallow-water submarine deltas.
Descrição
Palavras-chave
Benthic Foraminifera Climate variability Human impact Deltaic environments Alboran Sea
Contexto Educativo
Citação
Mendes, I., Lobo, F.J., Ferreira, Ó., López-González, N., Bárcenas, P., Fernandez-Salas, L.M., 2015. Guadalfeo and Adra submarine deltas evolution in response to sediment supply variations. VIII Symposium on the Iberian Atlantic Margin Proceedings, 21-23 September, Málaga, Spain, 627-630.