Slab Attachment in the Northern Apennines

In the last decade many efforts have been made to better understanding the geodynamical evolution of the Mediterranean region, considered in the general context of the interaction between the Eurasian and African macro-plates. In particular, the major source of new information on the nature of the lithospheric processes acting in the region during the last 20-30 million of years has been the application of tomographic techniques by different authors. A relevant part of the complex boundary between Eurasia and Africa is represented by the Apennines, and the upper mantle slab structure imaged by tomography beneath this mountain belt has been invoked as responsible for their arcuate, asymmetric structure. In the early '90s the idea of slab detachment was proposed as possible explanation for the non-continuous seismic velocity structure imaged by tomography beneath the Apennines as well as below other regions of the Mediterranean. In particular, lateral migration of the slab detachment from north to south along the Italian peninsula has been proposed as the engine driving the upper mantle dynamics beneath the Apennines. This view influenced numerous studies explaining different geophysical and geological data in the framework of the detachment process. However, in the same years other tomographic models suggested a different slab structure beneath the Apennines. Here we present a critical review of tomographic and geodynamic models and try to reconcile the major present day observables with different settings of the subducted lithosphere.