Efectos de la actividad tectónica reciente en la evolución y distribución de medios sedimentarios en la costa de Conil de la Frontera (Golfo de Cádiz, SO de España)

Abstract

In active tectonic zones, neo-tectonic efforts can alter the environment distribution, causing mix of sediments and fossils. In SW coast of Iberian Peninsula, there are evidences of tectonic activity, which caused changes in coastal zone. A high energy level and re-working processes, led to new deposits of similar features, by the mix of sediments and fossils, whose interpretation is difficult, due to lack of differentiation criteria. Sedimentary and Digital Terrain Model (DTM) studies in Salado river mouth (Conil de la Frontera), indicate a structural control, with rectilinear coastline and fluvial network and abrupt direction changes, as well as an old sandy mantle fixed by vegetation, and a recent engagement of the Salado river, evidenced by a height difference between the current channel and previous flood plain, while at current bank, a new alluvial floodplain is formed. Base level drop could be response to neo-tectonic activity, consisting of a tilting and subsequent fall in the sea level, although climatic/eustatic drop cannot be discounted. Changes affected to littoral environments, resulting in a regressive process and disconnection of direct marine action. Ages of marine shells contained in the deposits indicates a period from 869 BC to 22 AD, during which this was active.