The crustal structure of the western Po plain: Reconstruction from integrated geological and seismic data

A reflection/refraction seismic experiment performed in 1991 in the western Po plain gave basic data to constrain the interpretation of the crustal structures across the Alps/Apennines junction zones, Two different seismic domains, north and south of the western supposed prosecution of the Villalvernia-Varzi line, are evidenced from the interpretation of the data. The boundary between the two domains is characterized by strong lateral variations from southern high to northern low velocity layers, The northward abrupt deepening of the refractor/reflector basement is followed at depth by a similar deepening of the crust/mantle boundary. The geological interpretation evidences domains with coherent and independent evolution at surface level juxtaposed along oblique discontinuities cutting across the crust, A peculiar feature is the presence of both crust and mantle north-verging wedges into the crustal structure and the overthrust at depth of the 'alpine' metamorphic crust onto the 'apenninic' nappes (Monferrato region).