Crustal structure of Northern Latium (central Italy) from receiver functions analysis: new evidences of a post-collisional back-arc margin evolution.

The crustal velocity structure in a region of central Apennines of Italy at the hinge between the highly stretched portion of the Monte Argentario promontory and the magmatic province of the Tolfa Domes Complex (Northern Latium) is discussed in this study. S-wave velocities at depth have been constrained by the modeling of P-wave receiver functions (RF) from both temporary and permanent broadband seismic stations. The computer 3D Vs models show a thin crust (19-25. km) made of a shallow and thin sedimentary cover, a very high velocity and anisotropic layer related to a metamorphic basement, and a low Vs anisotropic layer in the middle-lower crust above a shallow Moho discontinuity modeled at about 20. km depth. The volcano-tectonic evolution of this portion of Tyrrhenian back-arc margin has been strongly influenced by its peculiar crustal architecture. The low-Vs layer acted as a shear zone in the middle-lower crust during the Tyrrhenian extension, also helping the development of Plio-Quaternary magmatism. Our findings potentially give new constraints on the evolution of the area and to the general comprehension of back-arc development in collisional regions.