Arquitectura de facies holocena del dominio fluvial del Estuario del Río Odiel (S.O. España)

Abstract

Five different lithofades constituted the holocene infilling of the Odiel estuary fluvial domain. These facies have been recognized by a sedimentological study of six drilling cores located along a transverse profile. The bedrock of the sequence are constituted by: a) Pleistocene gravels under the eastern sector, b) Carboniferous Culm facies under the central and deepest zone and d) Miocene marls under the western area. The Holocene sequence starts with a relict tidal reworked sandy gravel deposit (Facies 4). Above this material, the first clearly estuarine sediments consist in black sands with abundant organic muddy matrix and characteristic faunal assemblages (Facies 5). At the western margin, the fluvial floods build the estuarine bay head delta by coarse sand and gravel bodies (Facies 6 and 7), whereas at the eastern margin only estuarine muddy accretion bodies are deposited (Facies 8), because the floods cannot reach this less energetic zone. Thé Holocene sequence finishes with the installation of a wide floodplain where fine sands and sandy silts are the main sediment (Facies 9)