Thrust vs normal fault decollements in the Central Apennines

In the Central Apennines the Neogene-Quaternary normal faults and thrusts strike with different trends. Notoriously the normal faults followed and cut thrust planes progressively shifting their activity to the east. From the different trends of thrusts and normal faults, and on the base of their geometric relationship, we infer different depths of the décollement planes. Due to the slab retreat, compression and extension appear controlled by shear zones between the downgoing lithosphère and the mantle. Following these kinematics, the basal decollement of the accretionary prism is located at shallow level (upper crust), whereas the décollement of the extensional belt to the west appears located at the base of the crust in the hangingwall of the subduction. Therefore the thrust belt is thin-skinned and it appears to be more sensitive to the shallower Mesozoic inherited structure, generating undulations and transfer zones located at facies margins. The extensional belt is instead thick-skinned and the orientation of the normal faults is more independent of upper crust mechanical properties; they strike more linearly and they are probably controlled by deep crustal-scale decollements.