The influence of the evolution of the Pyrenees on adjacent basins

Abstract

Important thicknesses of syn- and post-orogenic sediments are observed in the southern part of the Aquitaine Basin and in the north of the Ebro Basin. Their deposition cannot be explained only as a result of the extensional history of the Early Cretaceous, thus the influence of the compression associated with the Pyrenees formation upon the subsidence of these basins is studied. Europe and Iberia are considered to behave as two semi-infinite elastic plates. The evolution through time of the sedimentary thicknesses is explained by the deflections of these two plates induced not only by the topographic load of the Pyrenees but also by additional forces (10 12 N/m) that may have their origin in the formation of a cold lithospheric root during the shortening. A series of calculations is presented for an approximately north-south profile across the Aquitaine Basin, the Pyrenees and the Ebro Basin; a good fit for the shape of the basins and the gravity anomalies was obtained, with flexural rigidities of 1.5·10 23. Nm for the northern plate and the outer part of the southern plate, and 1.4·10 21 Nm for the inner part, of the southern plate.