Subsidence history and continental margin evolution of the Western Pyrenean and Basque Basins
Abstract We have studied Cretaceous sedimentary sequences of four sedimentary basins along the European and north Iberian continental margins of the Western Pyrenean realm and the Basque Basin: the Depression Intermediaire, Sare-Vera basin and Ulzama basin in the Western Pyrenees and the Zumaya basin along the southern margin of the Bay of Biscay. The formation of these basins was largely due to Upper Cretaceous sinistral strike-slip tectonics during Iberian plate motion resulting in wrench basins (oblique-slip and pull-apart basins). A detailed biostratigraphic framework and paleobathymetric calculations based on sedimentologic and benthic foraminiferal data were used to construct decompacted and backstripped subsidence history curves for each basin. From these curves two major changes in subsidence history are apparent: (1) increased subsidence since Late Albian and (2) decrease in subsidence and/or initial uplift since Early Campanian. These changes are closely related to plate tectonic events, namely spreading in the Bay of Biscay followed by European-Iberian plate convergence.