Along-strike thickness variations of décollement levels controlling lateral changes in fold-and-thrust belts: the Barbastro-Balaguer Anticline (Southern Pyrenees)

European Geosciences Union General Assembly (2017. Viena)The subsurface vertical and lateral distribution of two evaporitic levels (Middle-Upper Triassic and Eocene) is here studied to better understand their role as a controlling factor on the geometry and kinematics of the central part of the South Pyrenean deformation front. Field work with hundreds of bedding attitudes, 5 exploration boreholes (up to 5000 m deep), the residual Bouguer anomaly and the interpretation of 27 seismic reflection profiles (approximately 440 km of sections) crossing the different allochthonous units and the adjacent Ebro foreland basin have been analysed in this work. Subsoil information is crucial because part of the studied area is extensively covered by the Oligocene-Miocene molasse that prevents any direct observation of the structure underneath to be done. Interpreted key horizons and faults have been identified from the lithological description of partially reinterpreted lithological well data and surface geology. Lithological well data has been anchored to seismic profiles by means of sonic log data. Kingdom software has been used to perform the 2D interpretation of seismic reflection profiles, supported by 2.5D gravity modelling, in a georeferenced workspace and then, surfaces of key horizons and faults were built and assembled together in a 3D model.Unidad de Zaragoza, Instituto Geológico y Minero de España, EspañaUnidad Asociada en Ciencias de la Tierra, Instituto Geológico y Minero de España, EspañaUnidad Asociada en Ciencias de la Tierra, Universidad de Zaragoza, EspañaDepartamento de Ciencias de la Tierra, Universidad de Zaragoza, EspañaDepartamento de Física, Universidad de Burgos, EspañaInstituto Geológico y Minero de España, EspañaInstitut de Ciències de la Terra Jaume Almera, Españ