Publication: Pliocene lithofacies within the marine geologic record from the Cadiz Bay (SW Spain): environment and processes
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Publication Date
2012
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Gutiérrez-Mas, José Manuel
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Sociedad Geológica de España
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Abstract
Mediante el estudio sedimentológico de los afloramientos Pliocenos de la costa de Cádiz (SO de España), se ha establecido la tendencia deposicional que caracteriza el relleno sedimentario ost-orogénico en el sector sur de la cuenca del Guadalquivir. Las facies indican variaciones importantes del régimen deposicional, alternando períodos estacionales de calma y tormenta con eventos ocasionales de muy alta energía, caracterizados por el depósito de materiales clásticos y bioclásticos de mayor tamaño. De acuerdo con las características sedimentarias y el contenido fósil, varios tipos de litofacies han sido identificadas. Las arenas, areniscas y calcarenitas muestran características que indican un régimen estacional, mientras que las capas bioclásticas y los depósitos de bloques muestran características completamente distintas a los depósitos intra y suprayacentes, habiendo sido clasificados como depósitos de eventos. También se ha discutido el origen de estos depósitos y los mecanismos deposicionales involucrados en su formación. Tanto las litofacies como el marco tectónico y el registro histórico, indican que estos depósitos fueron generados por eventos oceanográficos de muy alta energía, tales como grandes olas generadas por importantes temporales o tsunamis.
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.
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.