HOLOCENE SEDIMENTARY DYNAMICS ON THE IBERIAN CONTINENTAL-SHELF OF THEGULF-OF-CADIZ (SW SPAIN)

The Holocene evolution of the Iberian continental shelf of the Gulf of Cadiz (SW Spain) has been elucidated from a study of the granulometri c facies of surficial sediments and high-resolution seismic profiles. The relationship between different facies depends on eustatic events a nd oceanographic conditions associated with the North Atlantic Surfici al Water (NASW) on the shelf. A Transgressive Systems Tract (TST) deve loped as a response to a transgression (14,000-6500 yr) and deposited a transgressive sand bed on the transgressive (or ravinement) surface. A backstepping para-sequence related to a brief stillstand period has produced an onlapping shelf-transgressive erosion surface. The change in eustatic regime from transgressive to highstand in the last 6500 y ears has resulted in the formation of a sedimentary wedge of a Highsta nd Systems Tract (HST), extending from the mouth of the Guadalquivir r iver towards the southeast because of NASW circulation. These prodelta ic mud deposits are prograding over the older transgressive sand. The present surficial sediment distribution has been influenced greatly, t herefore, by the last eustatic rise of sea level and has been divided into three main areas: (a) the littoral area; (b) northern prodeltaic mud; and (c) a southern area of relict and palimpsest sand and muddy s and, generated in a high-energy littoral environment of the Late Pleis tocene-Holocene shoreline transgression. Copyright (C) 1996 Elsevier S cience Ltd