Contourites and gravity deposits of Faro Drift (Gulf of Cadiz): sediment provenance

espanolSe analizan los depositos del Pleistoceno de los sondeos U1386 y U1387 obtenidos en la Expedicion 339 IODP en los depositos (drift) de Faro para caracterizar: a) las litofacies, b) identificar los criterios mas utiles para distinguir entre contornitas y depositos de flujos por gravedad y c) determinar la procedencia de sedimentos. Se identifican tres litofacies, contornitas, turbiditas y debritas en base a resultados sedimentologicos y mineralogicos. Los criterios mas utiles para distinguir entre estos dos tipos de depositos son: i) la variacion vertical del tamano de grano y estructuras sedimentarias; ii) la distribucion de la frecuencia modal y iii) la composicion de los sedimentos. La mayoria del sedimento terrigeno de los depositos contorniticos proviene de la cuenca del Guadalquivir mientras que los sedimentos terrigenos de turbiditas y debrites proceden de las cuencas fluviales de Guadiana, Tinto-Odiel y los componentes biogenicos sugieren que proceden de ambientes deposicionales marinos someros. EnglishThePleistocene deposits of the Faro Drift at sites U1386 and U1387 with IODP 339 Exp. 339 have been examined to characterize: a) their lithofacies, b) for identifying the most used useful criteria for distinguishing between contourites and gravity flow deposits, and c) to determinate the sediment provenance. Three lithofacies, contourites, turbidites and debrites are defined based on sedimentological and mineralogical results. The most useful criteria for distinguishing between these two deposits are: i) the grain size vertical trend and sedimentary structures; ii) the modal frequency distribution, and iii) the sediment composition. Interpretation of sediment provenance of the different lithofacies reflects modes of long- and short-distance transport. Most of the terrigenous sediment of contourites is coming from the distant Guadalquivir drainage basin whereas those terrigenous sediment of turbidites and debrites are sourced by the vicinity fluvial drainage basins, Guadiana and Tinto-Odiel and biogenous components indicating shallow marine depositional environments.