Sedimentación deltaica tras una regresión forzada por la tectónica (Mioceno Superior, borde suroccidental de la Cuenca de Guadix)

Abstract

The marine deposits outcropping in the Cuadix Basin (Betic Cordillera) are made up of three upper Tortonian stratigraphic units: Unit I (TST: Transgressive Systems Tract), Unit II (HST: Highstand Systems Tract) and Unit III (LST: Lowstand Systems Tract). Unit III had not been identified in the southwest margin of the basin till this paper. This last marine unit is composed by a Cilbert-type delta which lies on the pelagic basin deposits of Unit II. The relative sea-level fall between Units II and III can be quantified on 200 m at least and it carried out a basinward migration of the shoreline of 2 km at least. Unit III developed desattached from the HST-shelf and slope systems, so defining a desattached lowstand systems tract (LST) in this sector of the basin. The tectonic uplifting of Sierra Nevada during uppermost Tortonian triggered the relative sea-level falling. Then, autocyclic factors controlled the Cilbert-type delta migration on a shallow sea poorly connected with the Atlantic and Mediterranean Sea.