Los depósitos transgresivos flandrienses de la plataforma continental del Golfo de Cádiz

Abstract

The analysis and interpretation of high-resolution seismic profiles collected in a sector of the Gulf of Cadiz continental shelf hve been used as a basis to characterise the Flandrian transgressive deposits developed after the last eustatic maximum. Four seismic units (TA to TJ have been attributed to the Transgressive System Tract (TST), and they represent coastal deposits developed during periods of sea-level stillstand during the last global rising trend. The stacking pattern, regional distribution and seismic facies of those seismic units are highly variable in a longitudinal direction, and two main kind of sedimentary environments have been identified: 1) Sector A, located offshore of the Guadiana river mouth, where the seismic units are disposed in a classical backstepping pattern. This continental shelf is a high-energy environment, dominated by the influence of storm events coming from the SW, resulting in the deposition of small infralittoral lithosomes. 2) Sector B, located offshore of the Donana National Park, where a low-gradient shelf developed during each transgressive stillstand, and large coastal depositional systems composed of marshes, lagoon, beaches and spit bars were formed as a consequence of southeastward redistribution of the sedimentary terrigenous supply introduced in this continental shelf by the main rivers