Geophysical investigation of the Isonzo Plain (NE Italy): imaging of the Dinaric-Alpine chain convergence zone

We present the results of a geophysical study carried out in the Isonzo Plain (NE of Italy), where the Paleogene External Dinarides and the Neogene eastern Southern Alps merge. We aim to provide imaging on the geological and tectonic setting in the area of convergence of the two chains. To this purpose multichannel seismic and geo-electrical profiles were acquired. Seismic processing and tomographic inversion of the first arrivals of multichannel seismic data were performed, allowing us to define geometries and velocities of the buried structures.Our data indicate the occurrence of a deformed Dinaric foredeep due to the Paleogene south-west migration of the External Dinaric chain and to the Neogene tectonic activity of the S-verging eastern South-Alpine chain. In addition, Plio-Quaternary transpressional fault systems produced structural highs such as the rocky outcrop of the Farra Hills rising from the plain. Plio-Quaternary tectonic activity displaced the late Miocene - Pliocene erosive surface at the top of the terrigenous sediment that fills the foredeep. The imaging of the buried structures provide a possible correlation with those outcropping in the Collio Hills and Karst Plateau.