Structural evolution of the Berzosa-Riaza extensional shear zone, Somosierra sector, Spanish Central System

In this paper, a new structural analysis of the Somosierra sector of the Spanish Central System is presented. Two main tectonothermal events are recorded: D1 is compressional and related to the variscan collision that produces northeast-eastward thrusting and associated folding; D2 has an extension nal character and produces, as the main feature, the development of a kilometric-scale ductile shear zone and a series of associated low grade detachments where D1 structures are overprinted and trasposed at all scales. The final structural pattern is completed by a set of late westward facing minor D3 structures that did not significantly modified the previous geometry