Los fondos de la franja sublitoral de Chipiona (Cádiz, SO España)

Abstract

During July 2010 was developed a survey of exploration of the sublittoral coastline located southwest of Chipiona (Cádiz) within the framework of the play of a documentary for National Geographic. The studied zone is located 5-14 meters depth under the extreme low water level. The aim of this campaign was the location of a supposed human settlement developed in a now-submerged paleocoast, however, the results of this survey ended up providing evidence of a geologic formation unknown in this stretch of the Cadiz coast. The results of side-scan sonar allowed the realization of a bed cartography and a delimitation of the outcrops. The study of the available materials and samples taken during different dives let identify the presence of a formation composed of quartzarenites and siltstones of the Lower Miocene with a synclyne morphology due to compressive movements and with evidence of a later extensional tectonics. Above this formation, Pleistocene materials typical of the coast of Cadiz (rock Oyster) and current sublittoral sediments are arranged in a discordant way. The discovered formation presents a great similarity with the sandstone of Aljibe, unit that is present in the Southern province of Cadiz, within the framework of the Flysch units of the Campo de Gibraltar.