Evolución tectonosedimentaria eocena de una parte del Pirineo central basada en un análisis litoestratigráfico del borde N de la cuenca de Graus (Huesca)

Abstract

Eocene tectosedimentary evolution of a part of the Central Pyrenees based on the lithostratigraphic analysis of the N border of the Graus Basin (Huesca, Spain)

The lithostratigraphic study of sedimentary episodes from the Lower-Middle Cuisian to Middle-Upper Eocene of the South-Pyrenean Graus basin (Huesca) is indirectly of diverse and transcendental importance. The presence of large horizons (kilometric order) composed of detrital materials of granitic origin associated to limestone elements of the Middle Cretaceous (Upper Albian-Lower Cenomanian, fundamentally) suggests that the paleogeography of this epoch was to the S of the North-Pyrenean fault, between the Ésera and Noguera Pallaresa rivers. This supposition is in accordance with the paleogeographic dispositive which was directly demonstrated to the N (Paloubard, Oust, France).

As a result of this fundamental deduction and the posterior tectonosedimentary evolution (during the Senonian-Paleocene), in the Cuisian, to the S of the North-Pyrenean fault, parts of the crystalline basement of the high primary range (axial zone) of the Central Pyrenees with a thin cover of Middle Cretaceous, were expos ed to erosion, furnish ing materials to the tertiary Graus basin. This event, together with the posterior sedimentary and structural evolution, suggests the origin of the allochthonous South-Pyrenean units.