Pliocene lithofacies within the marine geologic record from the Cádiz Bay (SW Spain): environments and processes.

Abstract

Depositional trend that characterized the post-orogenic sedimentary fill in the southern sector of the Guadalquivir Basin has been established by means of sedimentological analysis of Pliocene marine deposits from the Cadiz coast (SW Spain). Lithofacies indicate important variations of depositional regime, alternating calms and storm periods with occasional oceanographic events, which are characterized by the deposition of bioclastic and boulder deposits. According to the features and fossil content, several lithofacies types have been identified, from muddy sands to sandstones, calcarenites, bioclastic accumulations, and large boulder accumulations. Sands, sandstones and calcarenites show features which indicate a seasonal depositional regime, while bioclastic and large boulder beds show different features respect to the over and underlying beds, having been classified as event deposits. The origin of the event deposits and the involved depositional processes is also discussed. Both, lithofacies and tectonic setting are coherent with historical data, and indicate that these deposits were generated by very-high energy oceanographic events, such as major storms or tsunamis.