Secuencias deposicionales de tercer orden en el Eoceno de la Cuenca de antepaís surpirenaica oriental

Abstract

A basin analysis of the Eocene South-Eastern Pyrenean Foreland Basin shows a backstepped geometry of the basinfill made up of four main basin steps, each one infilled by a sedimentary sequence recognized as a third-order Depositional Sequence. This basin architectural stacking is due to a stepped evolution of the Foreland Basin as a response of a episodic orogenic wedge growth. The sequence boundary for each Depositional Sequence corresponds to a flooding/transgresive unconformity, controlled by the basin subsidence associated to the orogenic growth. The three lower sequences have the asymmetric pattern typical of foreland basins, including carbonates as the main depositional facies in the cratonward margin and a high siHciclastic input from the orogenic margin. In the three lower sequences, the basin fill shows an evolution from an initial underfilled basin stage to an overfilled final stage when alluvial fan deltas prograde from the orogenic margin. The carbonate facies in the cratoward margin show a general retrogradational pattern in both stages. The last depositional sequence shows a more symmetric geometry, including retrogradational and progradational siHciclastic depositional systems from Pyrenean and Catalonian coastal ranges provenance, due to a wrench tectonic activity in the Catalonian coastal ranges in that time