Miocene-Late Quaternary environmental changes and molluscs as proxies of MIS-1 transgression in the Tinto-Odiel estuary, SW Spain

This paper studies the malacofauna of four sediment cores collected in an old cove of the Tinto-Odiel estuary (SW Spain) to establish the chronology and spatial extent of MIS-1 transgression in this area. The paleoenvironmental interpretation based on facies analysis and the malacological record point to an evolution from a Miocene marine substrate to a final anthropic filling. During the late Pleistocene?-lower Holocene, this substrate was eroded by the fluvial network and alluvial sediments were deposited. During the maximum of the MIS-1 transgression (~ ca 6.5–5.4 kyr BP), this area was flooded and malacofauna is revealed as an excellent proxy of this transgression. Mesolittoral paleoenvironments dominated by the gastropod Peringia ulvae characterized the inner zones of the cove, while phanerogam meadows with abundant specimens of the gastropod Bittium reticulatum developed in the outermost areas. During the last 5400 years, this cove was progressively covered by marshes, although some mesolittoral paleoenvironments persisted until 4000 years BP.