A Late Pleistocene coastal plain pertaining to MIS 5 in the Gulf of Cádiz (mouth of the Guadalquivir River, SW Iberia)

Abstract

The geomorphological, sedimentological, topographical and chronological analysis of a large area located on the left bank of the Guadalquivir estuary (SW Iberian Peninsula), has enabled an extensive Late Pleistocene coastal plain to be defined, featuring a series of littoral strands. These rest uncomfortably on a rocky basal unit (BU) from the Lower Pleistocene, with an age of 1.1 Ma BP, showing shore platform morphology. The Late Pleistocene coastal plain presents a facies system where three stratigraphic units have been defined (CPU 1, 2 and 3). All units indicate the progradation of a littoral barrier system towards the sea and correspond to highstand MIS 5e2. Above these is located a red sands unit (RSU), interpreted as alluvial deposits, and indicative of a gradual drop in sea level and a progressive continentalization of the area. This unit was affected by karst processes. According to the topographic elevation of these littoral strands, the relative tectonic stability of the area and the regional correlation, the elevation of the deposits, about 7–8 m above the current mean sea level, could be considered as a reasonable representation of the eustatic level during MIS 5e2. This data could be useful for comparison with other regional determinations of MIS 5 sea level in Western Europe, and for future predictions of relative sea level rise in the area.