Estructuras de slump en faciès Buntsandstein del Pirineo Aragonés Oriental: Relevancia en la interpretación estratigráfica y relación con fallas sinsedimentarias

Abstract

Buntsandstein facies in Las Paules area of Oscensis Pyrenees is composed of conglomerates, sandstones, siltstones and marls. The thickness of the four stratigraphic sections range from 90 to 270 m, being organized in three megasequences. The two lowest are grain decreasing but upper one is more complex. The limit between second and third one is represented by sliding surfaces. Slump facies are characterized by synsedimentary folding, fault shear planes with s/ickensides and paleochannel geometries. There are also cracks and tensile fractures. All these structures have been plotted of four outcrops and the first one (Vilarru4 area) have been mapped on a 7:2000 topographic map. The result make us confidence of the NE-SW movement of the totalt mass. The inestability should be triggered by gravitacional sliding forced by NT 70-120 synsedimentary faults