Resumen de Evolución ambiental holocena del estuario del Oka (reserva de la biosfera de Urdaibai, sureste del golfo de Bizkaia): respuesta al ascenso postglacial del nivel del mar
Ane García Artola, Alejandro Cearreta Bilbao, Manuel Monge Ganuzas, B.P. Horton, D. Nikitina
Fluvial paleovalleys provide critical data to study the temporal superposition of depositional environments during the Holocene postglacial sea-level rise. We study eight boreholes that reached bedrock and a short replicate extracted from the Oka Estuary (Urdaibai Biosphere Reserve, southeastern Bay of Biscay). Benthic foraminifera and grain size allowed for paleoenvironmental reconstructions and radiocarbon dates put the sediment into a temporal framework.The sedimentary infill of the estuary shows a progressive shallowing of the estuary as rates of sea-level rise decreased during the Holocene: fluvial gravels on the bottom, marine and brackish intertidal sediments in the middle, and salt-marsh sediments on top. The sequence is topped by a few meters of anthropogenic deposits
