Kinematic interpretation of the Cañamares shear zone (central Iberian zone, Iberian Massif): from late Variscan strike-slip tectonics to Alpine deformation

Abstract

The Cañamares shear zone is located at the eastern end of the Spanish-Portuguese Central System, in the Central Iberian Zone of the Iberian Massif. It is a dextral transpressive structure, generated during the third Variscan deformation stage (D₃: 318-300 Ma), which was later reworked during the Permian and by Alpine tectonics. Once the local effects of later phases have been eliminated, the kinematic analysis of the Cañamares shear zone shows that it is a structure due to a monoclinic to slightly triclinic flow, with a vorticity dominated by the simple-shearing component (W_k > 0.81). The convergence direction of the blocks separated by the shear zone would have been N160°E to N-S. The convergence direction calculated for the Cañamares shear zone differs from that of other D₃ shear zones of the Iberian Massif. A comparison between these vectors would help to better understand the complexities of the final phases of the Variscan Orogeny in Iberia. However, the Cañamares shear zone lies at the core of an Alpine mega-fold and its current orientation does not probably reflect its primary geometry.