REE Geochemistry of Neogene–Holocene Sediments of La Fontanilla Cove (Tinto Estuary, SW Spain)

The Tinto and Odiel rivers (SW Spain) drain from a vast sulfide mining district join at 20-km-long estuary that enters the Atlantic Ocean. In this work, contents of rare earth elements (REE) fractionation in Neogene–Holocene sediment cores La Fontanilla cove (Tinto estuary) were studied. sediments collected depth 18 m different distances recent river flow analyzed for new information on temporal development REE load column. Results show ∑ is higher finer during periods activity prehistoric to times. Marine influence appears increase light (LREE) relative heavy (HREE). patterns these estuarine convex curvatures MREE LREE HREE, indicating presence acid-mixing processes between fluvial waters affected by acid mine drainage (AMD) seawater, as well precipitation poorly crystalline mineral phases. Significant positive Eu anomalies found ebb-tide channels marsh deposits, which can reflect mineralogical composition and/or strong localized salinity gradient combined with organic matter degradation. Sedimentological characteristics deposits appear play main role accumulation REE.