Connecting the Iberian Range with the Basque-Cantabrian Basin: The structure of the Sierra de Atapuerca (Spain)

Abstract

We present a structural model of the Sierra de Atapuerca which constitutes the transition zone between the Iberian Range and the southwestern Basque Cantabrian Basin, NW Spain, where the Sierra de Atapuerca is located. The interpretation integrates both subsurface well and seismic hydrocarbon exploration data with surface geology. According to our interpretation, the Sierra de Atapuerca consists of a pop-up basement involved structure and is part of a NW-SE transpressive strike-slip band formed by high-angle faults segmented by transfer faults with a NE-SW direction. All this strike-slip alignment is located in the northern area of the Duero Basin and forms the footwall of the Duero North Thrust, which has transported the Folded Band and the Burgalesa Platform over this area thanks to a Triassic detachment, in a thin-skinned tectonics context. The Rojas and NW Demanda tectonic arcs represent the structural terminations of the Basque-Cantabrian Basin and Iberian Range domains, respectively, with the Sierra de Atapuerca located between both. The current structure of this zone is the result of an Alpine tectonic inversion of a previous Mesozoic extensional configuration, inherited from late Hercynian faults.