Pliegues flexurales asociados al cabalgamiento de la Sierra de la Demanda en el Cerro Penalba (La Rioja)

Abstract

The Cerro Penalbà fold system is located at the northern border of the Sierra de la Demanda, within a thrust sheet, up tp 500 m thick, formed by overturned marine Jurassic beds, This thrust sheet is located between paleozoic rocks to the south, and (he tertiary molasse of the Ebro basin, to the north. This fold system is composed by at least three N W vergent asymmetric folds, with axes striking NOSOEand plunging 30 °-50 ° to the SW. The geometry and orientation of these folds is interpreted in terms of simple shear associated to the NNW movement of the hangingwall of the Sierra de la Demanda thrust. Kinematic indicators hear the thrust surface (slickenside striations and fracture cleavage), and the overall geometry of the main thrust, are consistent with this transport direction