Tordera river delta system build up (Ne iberian Peninsula): Sedimentary sequences and offshore correlation

Abstract

The Tordera River Delta is made up of coarse sand bodies which were formed during the last sea level rise. Marine and land seismic profiles and wells show three depositional Holocene sequences corresponding to a) the transgressive base level, b) the progradant intermediate unit and c) the progradant unit which onlaps the Plio-Pleistocene sequence seawards and the granitic basement on the present delta plain and northern coast. The morphology of the sedimentary bodies, isobath maps and marine geophysical data enabled us to gain fresh insights into the evolution of the delta and its prodelta and into the various relict sand bodies on the inner shelf. The evolution of the coastline can be followed during the prograding process of the lower units from the successive coastal and internal lagoons. These coastal lagoons were conditioned by river changes and basement morphology. Once the sea level max imum was attained, the prograding units covered these morphologies, resulting in the present delta configuration.